thomson electron experiment

Structure of Atom

Cathode Ray Experiment

What is cathode ray tube.

A cathode-ray tube (CRT) is a vacuum tube in which an electron beam, deflected by applied electric or magnetic fields, produces a trace on a fluorescent screen.

The function of the cathode ray tube is to convert an electrical signal into a visual display. Cathode rays or streams of electron particles are quite easy to produce, electrons orbit every atom and move from atom to atom as an electric current.

Cathode ray tube, recommended videos.

J.J.Thomson Experiment

Apparatus Setup

Procedure of the experiment.

Frequently Asked Questions – FAQs

In a cathode ray tube, electrons are accelerated from one end of the tube to the other using an electric field. When the electrons hit the far end of the tube they give up all the energy they carry due to their speed and this is changed to other forms such as heat. A small amount of energy is transformed into X-rays.

The cathode ray tube (CRT), invented in 1897 by the German physicist Karl Ferdinand Braun, is an evacuated glass envelope containing an electron gun a source of electrons and a fluorescent light, usually with internal or external means to accelerate and redirect the electrons. Light is produced when electrons hit a fluorescent tube.

The electron beam is deflected and modulated in a manner that allows an image to appear on the projector. The picture may reflect electrical wave forms (oscilloscope), photographs (television, computer monitor), echoes of radar-detected aircraft, and so on. The single electron beam can be processed to show movable images in natural colours.

J. J. Thomson Experiment – The Discovery of Electron

The Cathode ray experiment was a result of English physicists named J. J. Thomson experimenting with cathode ray tubes. During his experiment he discovered electrons and it is one of the most important discoveries in the history of physics. He was even awarded a Nobel Prize in physics for this discovery and his work on the conduction of electricity in gases.

However, talking about the experiment, J. J. Thomson took a tube made of glass containing two pieces of metal as an electrode. The air inside the chamber was subjected to high voltage and electricity flowing through the air from the negative electrode to the positive electrode.

J. J. Thomson designed a glass tube that was partly evacuated, i.e. all the air had been drained out of the building. He then applied a high electric voltage at either end of the tube between two electrodes. He observed a particle stream (ray) coming out of the negatively charged electrode (cathode) to the positively charged electrode (anode). This ray is called a cathode ray and is called a cathode ray tube for the entire construction.

The experiment Cathode Ray Tube (CRT) conducted by J. J. Thomson, is one of the most well-known physical experiments that led to electron discovery . In addition, the experiment could describe characteristic properties, in essence, its affinity to positive charge, and its charge to mass ratio. This paper describes how J is simulated. J. Thomson experimented with Cathode Ray Tube.

The major contribution of this work is the new approach to modelling this experiment, using the equations of physical laws to describe the electrons’ motion with a great deal of accuracy and precision. The user can manipulate and record the movement of the electrons by assigning various values to the experimental parameters.

A Diagram of JJ.Thomson Cathode Ray Tube Experiment showing Electron Beam – A cathode-ray tube (CRT) is a large, sealed glass tube.

The apparatus of the experiment incorporated a tube made of glass containing two pieces of metals at the opposite ends which acted as an electrode. The two metal pieces were connected with an external voltage. The pressure of the gas inside the tube was lowered by evacuating the air.

Apparatus is set up by providing a high voltage source and evacuating the air to maintain the low pressure inside the tube.
High voltage is passed to the two metal pieces to ionize the air and make it a conductor of electricity.
The electricity starts flowing as the circuit was complete.
To identify the constituents of the ray produced by applying a high voltage to the tube, the dipole was set up as an add-on in the experiment.
The positive pole and negative pole were kept on either side of the discharge ray.
When the dipoles were applied, the ray was repelled by the negative pole and it was deflected towards the positive pole.
This was further confirmed by placing the phosphorescent substance at the end of the discharge ray. It glows when hit by a discharge ray. By carefully observing the places where fluorescence was observed, it was noted that the deflections were on the positive side. So the constituents of the discharge tube were negatively charged.

After completing the experiment J.J. Thomson concluded that rays were and are basically negatively charged particles present or moving around in a set of a positive charge. This theory further helped physicists in understanding the structure of an atom . And the significant observation that he made was that the characteristics of cathode rays or electrons did not depend on the material of electrodes or the nature of the gas present in the cathode ray tube. All in all, from all this we learn that the electrons are in fact the basic constituent of all the atoms.

Most of the mass of the atom and all of its positive charge are contained in a small nucleus, called a nucleus. The particle which is positively charged is called a proton. The greater part of an atom’s volume is empty space.

The number of electrons that are dispersed outside the nucleus is the same as the number of positively charged protons in the nucleus. This explains the electrical neutrality of an atom as a whole.

Uses of Cathode Ray Tube

Used as a most popular television (TV) display.
X-rays are produced when fast-moving cathode rays are stopped suddenly.
The screen of a cathode ray oscilloscope, and the monitor of a computer, are coated with fluorescent substances. When the cathode rays fall off the screen pictures are visible on the screen.

Frequently Asked Questions – FAQs

What are cathode ray tubes made of.

The cathode, or the emitter of electrons, is made of a caesium alloy. For many electronic vacuum tube systems, Cesium is used as a cathode, as it releases electrons readily when heated or hit by light.

Where can you find a cathode ray tube?

Cathode rays are streams of electrons observed in vacuum tubes (also called an electron beam or an e-beam). If an evacuated glass tube is fitted with two electrodes and a voltage is applied, it is observed that the glass opposite the negative electrode glows from the electrons emitted from the cathode.

How did JJ Thomson find the electron?

In the year 1897 J.J. Thomson invented the electron by playing with a tube that was Crookes, or cathode ray. He had shown that the cathode rays were charged negatively. Thomson realized that the accepted model of an atom did not account for the particles charged negatively or positively.

What are the properties of cathode rays?

They are formed in an evacuated tube via the negative electrode, or cathode, and move toward the anode. They journey straight and cast sharp shadows. They’ve got strength, and they can do the job. Electric and magnetic fields block them, and they have a negative charge.

What do you mean by cathode?

A device’s anode is the terminal on which current flows in from outside. A device’s cathode is the terminal from which current flows out. By present, we mean the traditional positive moment. Because electrons are charged negatively, positive current flowing in is the same as outflowing electrons.

Who discovered the cathode rays?

Studies of cathode-ray began in 1854 when the vacuum tube was improved by Heinrich Geissler, a glassblower and technical assistant to the German physicist Julius Plücker. In 1858, Plücker discovered cathode rays by sealing two electrodes inside the tube, evacuating the air and forcing it between the electrode’s electric current.

Which gas is used in the cathode ray experiment?

For better results in a cathode tube experiment, an evacuated (low pressure) tube is filled with hydrogen gas that is the lightest gas (maybe the lightest element) on ionization, giving the maximum charge value to the mass ratio (e / m ratio = 1.76 x 10 ^ 11 coulombs per kg).

What is the Colour of the cathode ray?

Cathode-ray tube (CRT), a vacuum tube which produces images when electron beams strike its phosphorescent surface. CRTs can be monochrome (using one electron gun) or coloured (using usually three electron guns to produce red, green, and blue images that render a multicoloured image when combined).

How cathode rays are formed?

Cathode rays come from the cathode because the cathode is charged negatively. So those rays strike and ionize the gas sample inside the container. The electrons that were ejected from gas ionization travel to the anode. These rays are electrons that are actually produced from the gas ionization inside the tube.

What are cathode rays made of?

Thomson showed that cathode rays were composed of a negatively charged particle, previously unknown, which was later named electron. To render an image on a screen, Cathode ray tubes (CRTs) use a focused beam of electrons deflected by electrical or magnetic fields.

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Discovering the electron: JJ Thomson and the Cathode Ray Tube

Concept Introduction: JJ Thomson and the Discovery of the Electron

The discovery of the electron was an important step for physics, chemistry, and all fields of science. JJ Thomson made the discovery using the cathode ray tube. Learn all about the discovery, the importance of the discovery, and JJ Thomson in this tutorial article.

Who was JJ Thomson?

JJ Thomson was an English physicist who is credited with discovery of the electron in 1897. Thompson was born in December 1856 in Manchester, England and was educated at the University of Manchester and then the University of Cambridge, graduating with a degree in mathematics. Thompson made the switch to physics a few years later and began studying the properties of cathode rays. In addition to this work, Thomson also performed the first-ever mass spectrometr y experiments, discovered the first isotope and made important contributions both to the understanding of positively charged particles and electrical conductivity in gases.

Thomson did most of this work while leading the famed Cavendish Laboratory at the University of Cambridge. Although he received the Nobel Prize in physics and not chemistry, Thomson’s contributions to the field of chemistry are numerous. For instance, the discovery of the electron was vital to the development of chemistry today, and it was the first subatomic particle to be discovered. The proton and the neutron would soon follow as the full structure of the atom was discovered.

What is a cathode ray tube and why was it important?

Prior to the discovery of the electron, several scientists suggested that atoms consisted of smaller pieces. Yet until Thomson, no one had determined what these might be. Cathode rays played a critical role in unlocking this mystery. Thomson determined that charged particles much lighter than atoms , particles that we now call electrons made up cathode rays. Cathode rays form when electrons emit from one electrode and travel to another. The transfer occurs due to the application of a voltage in vacuum. Thomson also determined the mass to charge ratio of the electron using a cathode ray tube, another significant discovery.

How did Thomson make these discoveries?

Thomson was able to deflect the cathode ray towards a positively charged plate deduce that the particles in the beam were negatively charged. Then Thomson measured how much various strengths of magnetic fields bent the particles. Using this information Thomson determined the mass to charge ratio of an electron. These were the two critical pieces of information that lead to the discovery of the electron. Thomson was now able to determine that the particles in question were much smaller than atoms, but still highly charged. He finally proved atoms consisted of smaller components, something scientists puzzled over for a long time. Thomson called the particle “corpuscles” , not an electron. George Francis Fitzgerald suggested the name electron.

Why was the discovery of the electron important?

The discovery of the electron was the first step in a long journey towards a better understanding of the atom and chemical bonding. Although Thomson didn’t know it, the electron would turn out to be one of the most important particles in chemistry. We now know the electron forms the basis of all chemical bonds. In turn chemical bonds are essential to the reactions taking place around us every day. Thomson’s work provided the foundation for the work done by many other important scientists such as Einstein, Schrodinger, and Feynman.

Interesting Facts about JJ Thomson

Not only did Thomson receive the Nobel Prize in physics in 1906 , but his son Sir George Paget Thomson won the prize in 1937. A year earlier, in 1936, Thomson wrote an autobiography called “Recollections and Reflections”. He died in 1940, buried near Isaac Newton and Charles Darwin. JJ stands for “Joseph John”. Strangely, another author with the name JJ Thomson wrote a book with the same name in 1975. Thomson had many famous students, including Ernest Rutherford.

Discovery of the Electron: Further Reading

Protons, Neutrons & Electrons Discovering the nucleus with gold foil Millikan oil drop experiment Phase Diagrams

Subatomic science: JJ Thomson's discovery of the electron

Read about how JJ Thomson announced his discovery of the electron at the Royal Institution in this blog by our Head of Heritage and Collections.

JJ Thomson, while familiar to scientists, is not necessarily a name most people would recognise; however, anyone who has undertaken any science at school will have heard of an electron.

It is Thomson we have to thank for discovering this fundamental breakthrough in science and announcing his discovery to the world during a lecture here at the Royal Institution in 1897.

Painting of an elderly man with greying hair and a handlebar moustache wearing black academic robes, a white shirt and thin red scarf

What is an electron?

The technical definition is:

"An electron is a stable subatomic particle with a negative electrical charge. Unlike protons and neutrons, electrons are not constructed from even smaller components."

As a non-scientist this definition is something I have heard before but must confess is not something that means a great deal to me. It is an explanation in its basic form but doesn’t convey really what an electron is or what the impact of its discovery made

John Dalton's atomic theory

Prior to 1897, scientists had hypothesised about the makeup of the universe at the atomic and subatomic level but had not been able to prove any theories. The atom had been known about for many years.

In 1808, chemist John Dalton developed an argument that led to a realisation: that perhaps all matter, the things or objects that make up the universe are made of tiny, little bits.

These are fundamental and indivisible bits and named after the ancient Greek words ‘a’ meaning not and ‘tomos’ meaning cut therefore ‘atomos’ or uncuttable. Atoms.

JJ Thomson's cathode ray tube experiments

Thomson, a highly respected theoretical physics professor at Cambridge University, undertook a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube – he was attempting to solve a long-standing controversy regarding the nature of cathode rays, which occur when an electric current is driven through a vessel from which most of the air or other gas has been pumped out.

This was something that many scientists were investigating at the time. It was Thomson that made the breakthrough however, concluding through his experimentation that particles making up the rays were 1,000 times lighter than the lightest atom, proving that something smaller than atoms existed.

Thomson likened the composition of atoms to plum pudding, with negatively-charged ‘corpuscles’ dotted throughout a positively charged field.

A glass sphere with glass tubes at either end and metal bars inside

G Johnstone Stoney coins the term 'electron'

Thomson explained within his lecture all of his experiments and the results, never mentioning the word electron but instead sticking to corpuscles to explain these tiny particles in the same terms as biological cells (corpuscles are a minute body or cell in an organism).

Such would they have remained if not for the term 'electron' coined by G Johnstone Stoney who in 1891 denoted the unit of charge found in experiments that passed electrical current through chemicals.

It was then in 1897 after Thomson’s publication of his research that Irish physicist George Francis Fitzgerald suggested that the term be applied to Thomson's research instead of corpuscles to better describe these newly discovered subatomic particles.

JJ Thomson and the Royal Institution

Thomson had a long-standing relationship with the Royal Institution during his long academic career in Cambridge, lecturing many times on the development of physics through Discourses and educational lectures to all ages.

Thomson was a great friend of Sir William Henry Bragg and Sir William Lawrence Bragg, who jointly won the Nobel Prize in 1915 for the development of x-ray crystallography, and who were both former Director’s of the Royal Institution.

JJ Thomson's Nobel Prize

Thomson received the Nobel Prize for his work in Physics in 1906 and was knighted in 1908. The studies of nuclear organisation that continue even to this day and the further identification of elementary particles have all followed the accomplishments of Thomson and his discovery in 1897.

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John Tyndall set the foundation for our modern understanding of the greenhouse effect, climate change, meteorology, and weather

J. J. Thomson and the Existence of the Electron

J. J. Thomson (1856 – 1940)

On April 30 , 1897 , English physicist Joseph John Thomson gave the first experimental proof of the electron , which had been already theoretically predicted by Johnstone Stoney . Thomson was awarded the 1906 Nobel Prize in Physics for the discovery of the electron and for his work on the conduction of electricity in gases.

“As the cathode rays carry a charge of negative electricity, are deflected by an electrostatic force as if they were negatively electrified, and are acted on by a magnetic force in just the way in which this force would act on a negatively electrified body moving along the path of these rays, I can see no escape from the conclusion that they are charges of negative electricity carried by particles of matter.” – J. J. Thomson, “Cathode rays” Philosophical Magazine, 44, 293 (1897).

Background J. J. Thomson

Joseph John Thomson was born in 1856 in Manchester, England and was taught mainly in private schools at the beginning. In 1876 , he enrolled at Trinity College, Cambridge where he received his Bachelor’s and Master’s degree . When Thomson became Cavendish Professor of Physics , Ernest Rutherford was among his students and later on, he succeeded Thomson in the post. Thomson was known to be an excellent teacher. Seven of his research assistants and his son were able to win the Nobel Prizes in physics . Thomson himself was awarded the famous prize in 1906 “ in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases. ” Two years later, he was knighted. In 1918 , Thomson became Master of the Trinity College in Cambridge .

The Discovery of the Electron

“The electron: may it never be of any use to anybody!” – A popular toast or slogan at J. J. Thomson’s Cavendish Laboratory in the first years of the 1900s, as quoted [9]

The fact that atoms were built up from a more fundamental unit was already suggested by scientists like William Prout or Norman Lockyer . However, J. J. Thomson was the first known scientist to suggest that the fundamental unit was over 1000 times smaller than an atom. Today, the subatomic particle is known as the electron . To achieve this discovery, Thomson used his explorations on the properties of cathode rays. He published his suggestion on 30 April 1897 following his discovery that Lenard rays could travel much further through air than expected for an atom-sized particle. At first, he estimated the mass of cathode rays through the heat that was generated when the rays hit a thermal junction. Then Thomson compared his result with the magnetic deflection of the rays.

J. J. Thomson’s cathode ray tube with electromagnetic deflection coils

Discovering Evidence for Isotopes

Next to this famous discovery, Thomson and his research assistant F. W. Aston channeled a stream of neon ions through a magnetic and an electric field . They measured its deflection and observed two patches of light on the photographic plate , which was placed in the path. They concluded, that neon is composed of atoms of two different atomic masses ( isotopes ), which was the first evidence for isotopes of a stable element. Also, Thomson’s separation of neon isotopes by their mass was the first example of mass spectrometry . In 1905 , Thomson discovered the natural radioactivity of potassium and one year later he managed to demonstrate that hydrogen had only a single electron per atom.

In the bottom right corner of this photographic plate are markings for the two isotopes of neon: neon-20 and neon-22.

In 1884 Thomson was elected a Fellow of the Royal Society, which awarded him the Royal Medal in 1894, the Hughes Medal in 1902 and the Copley Medal in 1914. In 1902 he was elected to the American Academy of Arts and Sciences, in 1903 to the National Academy of Sciences. In 1906 he was awarded the Nobel Prize in Physics for his research on the electrical conductivity of gases. Thomson was awarded a Knight Bachelor’s degree in 1908 and was admitted to the Order of Merit in 1912. Since 1907 he was a corresponding member of the Bavarian Academy of Sciences. In 1911 he was elected as an external member of the Göttingen Academy of Sciences.

From 1918 until his death in 1940 he was Head of Trinity College and from 1916 to 1920 President of the Royal Society . Thomson’s ashes were buried at Westminster Abbey (near Sir Isaac Newton).

References and Further Reading:

[1] The Discovery of the Electron
[2] Thomson’s discovery of the isotopes of Neon
[3] J. J. Thomson’s Nobel Lecture
[4] Ernest Rutherford Discovers the Nucleus , SciHi Blog
[5] J. J. Thomson at Wikidata
[6] Works by or about J. J. Thomson at Internet Archive
[7] A short film of Thomson lecturing on electrical engineering and the discovery of the electron (1934)
[8] J.J. Thomson (1897), Cathode rays , Philosophical Magazine , 44, 293
[9] Proceedings of the Royal Institution of Great Britain, Volume 35 (1951), p. 251.
[10] Kathy Joseph, J. J. Thomson Cathode Ray Tube Experiment: the Discovery of the Electron , Kathy Loves Physics & History @ youtube
[11] Rayleigh (1941). “Joseph John Thomson. 1856-1940” . Obituary Notices of Fellows of the Royal Society . 3 (10): 586–609.
[12] “Joseph John “J. J.” Thomson” . Science History Institute . June 2016 .
[13] Thomson, J. J. (June 1906). “On the Number of Corpuscles in an Atom” . Philosophical Magazine . 11 (66): 769–781
[14] Thomson, J. J. (1905). “On the emission of negative corpuscles by the alkali metals” . Philosophical Magazine . Series 6. 10 (59): 584–590.
[15] Timeline for J. J. Thomson, via Wikidata

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Supplement to Experiment in Physics

Appendix 7: evidence for a new entity: j.j. thomson and the electron.

In discussing the existence of electrons Ian Hacking has written, “So far as I’m concerned, if you can spray them then they are real” (Hacking 1983, p. 23). He went on to elaborate this view. “We are completely convinced of the reality of electrons when we set out to build—and often enough succeed in building—new kinds of device that use various well-understood causal properties of electrons to interfere in other more hypothetical parts of nature” (p. 265).

Hacking worried that the simple manipulation of the first quotation, the changing of the charge on an oil drop or on a superconducting niobium sphere, which involves only the charge of the electron, was insufficient grounds for belief in electrons. His second illustration, which he believed more convincing because it involved several properties of the electron, was that of Peggy II, a source of polarized electrons built at the Stanford Linear Accelerator Center in the late 1970s. Peggy II provided polarized electrons for an experiment that scattered electrons off deuterium to investigate the weak neutral current. Although I agree with Hacking that manipulability can often provide us with grounds for belief in a theoretical entity, [ 1 ] his illustration comes far too late. Physicists were manipulating the electron in Hacking’s sense in the early twentieth century. [ 2 ] They believed in the existence of electrons well before Peggy II, and I will argue that they had good reasons for that belief.

The position I adopt is one that might reasonably be called “conjectural” realism. It is conjectural because, despite having good reasons for belief in the existence of an entity or in the truth of a scientific law, we might be wrong. At one time scientists had good reason to believe in phlogiston and caloric, substances we now have good reason to believe don’t exist. My position includes both Sellars’ view that “to have good reason for holding a theory is ipso facto to have good reason for holding that the entities postulated by the theory exist” (Sellars 1962, p. 97), and the “entity realism” proposed by Cartwright (1983) and by Hacking (1983). Both Hacking, as noted above, and Cartwright emphasize the manipulability of an entity as a criterion for belief in its existence. Cartwright also stresses causal reasoning as part of her belief in entities. In her discussion of the operation of a cloud chamber she states, “…if there are no electrons in the cloud chamber, I do not know why the tracks are there” (Cartwright, 1983, p.99). In other words, if such entities don’t exist then we have no plausible causal story to tell. Both Hacking and Cartwright grant existence to entities such as electrons, but do not grant “real” status to either laws or theories, which may postulate or apply to such entities.

In contrast to both Cartwright and Hacking, I suggest that we can also have good reasons for belief in the laws and theories governing the behavior of the entities, and that several of their illustrations implicitly involve such laws. [ 3 ] I have argued elsewhere for belief in the reality of scientific laws (Franklin 1996). In this section I shall concentrate on the reality and existence of entities, in particular, the electron. I agree with both Hacking and Cartwright that we can go beyond Sellars and have good reasons for belief in entities even without laws. Hacking and Cartwright emphasize experimenting with entities. I will argue that experimenting on entities and measuring their properties can also provide grounds for belief in their existence.

In this section I will discuss the grounds for belief in the existence of the electron by examining J.J. Thomson’s experiments on cathode rays. His 1897 experiment on cathode rays is generally regarded as the “discovery” of the electron.

The purpose of J.J. Thomson’s experiments was clearly stated in the introduction to his 1897 paper.

The experiments discussed in this paper were undertaken in the hope of gaining some information as to the nature of Cathode Rays. The most diverse opinions are held as to these rays; according to the almost unanimous opinion of German physicists they are due to some process in the aether to which—inasmuch as in a uniform magnetic field their course is circular and not rectilinear—no phenomenon hitherto observed is analogous: another view of these rays is that, so far from being wholly aetherial, they are in fact wholly material, and that they mark the paths of particles of matter charged with negative electricity (Thomson 1897, p. 293).

Thomson’s first order of business was to show that the cathode rays carried negative charge. This had presumably been shown previously by Perrin. Perrin placed two coaxial metal cylinders, insulated from one another, in front of a plane cathode. The cylinders each had a small hole through which the cathode rays could pass onto the inner cylinder. The outer cylinder was grounded. When cathode rays passed into the inner cylinder an electroscope attached to it showed the presence of a negative electrical charge. When the cathode rays were magnetically deflected so that they did not pass through the holes, no charge was detected. “Now the supporters of the aetherial theory do not deny that electrified particles are shot off from the cathode; they deny, however, that these charged particles have any more to do with the cathode rays than a rifle-ball has with the flash when a rifle is fired” (Thomson 1897, p. 294).

Thomson repeated the experiment, but in a form that was not open to that objection. The apparatus is shown in Figure 14. The two coaxial cylinders with holes are shown. The outer cylinder was grounded and the inner one attached to an electrometer to detect any charge. The cathode rays from A pass into the bulb, but would not enter the holes in the cylinders unless deflected by a magnetic field.

Figure 14. Thomson’s apparatus for demonstrating that cathode rays have negative charge. The slits in the cylinders are shown. From Thomson (1897).

When the cathode rays (whose path was traced by the phosphorescence on the glass) did not fall on the slit, the electrical charge sent to the electrometer when the induction coil producing the rays was set in action was small and irregular; when, however, the rays were bent by a magnet so as to fall on the slit there was a large charge of negative electricity sent to the electrometer…. If the rays were so much bent by the magnet that they overshot the slits in the cylinder, the charge passing into the cylinder fell again to a very small fraction of its value when the aim was true. Thus this experiment shows that however we twist and deflect the cathode rays by magnetic forces, the negative electrification follows the same path as the rays, and that this negative electrification is indissolubly connected with the cathode rays (Thomson 1897, p. 294–295, emphasis added).

This experiment also demonstrated that cathode rays were deflected by a magnetic field in exactly the way one would expect if they were negatively charged material particles. [ 4 ]

Figure 15. Thomson’s apparatus for demonstrating that cathode rays are deflected by an electric field. It was also used to measure $\bfrac{m}{e}$. From Thomson (1897).

There was, however, a problem for the view that cathode rays were negatively charged particles. Several experiments, in particular those of Hertz, had failed to observe the deflection of cathode rays by an electrostatic field. Thomson proceeded to answer this objection. His apparatus is shown in Figure 15. Cathode rays from C pass through a slit in the anode A, and through another slit at B. They then passed between plates D and E and produced a narrow well-defined phosphorescent patch at the end of the tube, which also had a scale attached to measure any deflection. When Hertz had performed the experiment he had found no deflection when a potential difference was applied across D and E. He concluded that the electrostatic properties of the cathode ray are either nil or very feeble. Thomson admitted that when he first performed the experiment he also saw no effect. “on repeating this experiment [that of Hertz] I at first got the same result [no deflection], but subsequent experiments showed that the absence of deflexion is due to the conductivity conferred on the rarefied gas by the cathode rays”. [ 5 ] On measuring this conductivity it was found that it diminished very rapidly as the exhaustion increased; it seemed that on trying Hertz’s experiment at very high exhaustion there might be a chance of detecting the deflexion of the cathode rays by an electrostatic force (Thomson 1897, p. 296). Thomson did perform the experiment at lower pressure [higher exhaustion] and observed the deflection. [ 6 ]

Thomson concluded:

As the cathode rays carry a charge of negative electricity, are deflected by an electrostatic force as if they were negatively electrified, and are acted on by a magnetic force in just the way in which this force would act on a negatively electrified body moving along the path of these rays, I can see no escape from the conclusion that they are charges of negative electricity carried by particles of matter. (Thomson 1897, p. 302) [ 7 ]

Having established that cathode rays were negatively charged material particles, Thomson went on to discuss what the particles were. “What are these particles? are they atoms, or molecules, or matter in a still finer state of subdivision” (p. 302). To investigate this question Thomson made measurements on the charge to mass ratio of cathode rays. Thomson’s method used both the electrostatic and magnetic deflection of the cathode rays. [ 8 ] The apparatus is shown in Figure 15. It also included a magnetic field that could be created perpendicular to both the electric field and the trajectory of the cathode rays.

Let us consider a beam of particles of mass $m$ charge $e$, and velocity $v$. Suppose the beam passes through an electric field F in the region between plates D and E, which has a length $L$. The time for a particle to pass through this region $t = \bfrac{L}{v}$. The electric force on the particle is $Fe$ and its acceleration $a = \bfrac{Fe}{m}$. The deflection d at the end of the region is given by

Now consider a situation in which the beam of cathode rays simultaneously pass through both $F$ and a magnetic field $B$ in the same region. Thomson adjusted $B$ so that the beam was undeflected. thus the magnetic force was equal to the electrostatic force.

This determined the velocity of the beam. Thus,

Each of the quantities in the above expression was measured so the $\bfrac{e}{m}$ or $\bfrac{m}{e}$ could be determined.

Using this method Thomson found a value of $\bfrac{m}{e}$ of $(1.29\pm 0.17) \times 10^{-7}$. This value was independent of both the gas in the tube and of the metal used in the cathode, suggesting that the particles were constituents of the atoms of all substances. It was also far smaller, by a factor of 1000, than the smallest value previously obtained, $10^{-4}$, that of the hydrogen ion in electrolysis.

Thomson remarked that this might be due to the smallness of $m$ or to the largeness of $e$. He argued that $m$ was small citing Lenard’s work on the range of cathode rays in air. The range, which is related to the mean free path for collisions, and which depends on the size of the object, was 0.5 cm. The mean free path for molecules in air was approximately $10^{-5}$ cm. If the cathode ray traveled so much farther than a molecule before colliding with an air molecule, Thomson argued that it must be much smaller than a molecule. [ 9 ]

Thomson had shown that cathode rays behave as one would expect negatively charged material particles to behave. They deposited negative charge on an electrometer, and were deflected by both electric and magnetic fields in the appropriate direction for a negative charge. In addition the value for the mass to charge ratio was far smaller than the smallest value previously obtained, that of the hydrogen ion. If the charge were the same as that on the hydrogen ion, the mass would be far less. In addition, the cathode rays traveled farther in air than did molecules, also implying that they were smaller than an atom or molecule. Thomson concluded that these negatively charged particles were constituents of atoms. In other words, Thomson’s experiments had given us good reasons to believe in the existence of electrons.

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J.J.. Thomson - Nobel Lecture: Electronic Waves

George Paget Thomson

Nobel lecture.

Nobel Lecture, June 7, 1938

Electronic Waves

Ever since last November, I have been wanting to express in person my gratitude to the generosity of Alfred Nobel, to whom I owe it that I am privileged to be here today, especially since illness prevented me from doing so at the proper time. The idealism which permeated his character led him to make his magnificent foundation for the benefit of a class of men with whose aims and viewpoint his own scientific instincts and ability had made him naturally sympathetic, but he was certainly at least as much concerned with helping science as a whole, as individual scientists. That his foundation has been as successful in the first as in the second, is due to the manner in which his wishes have been carried out. The Swedish people, under the leadership of the Royal Family, and through the medium of the Royal Academy of Sciences, have made the Nobel Prizes one of the chief causes of the growth of the prestige of science in the eyes of the world, which is a feature of our time. As a recipient of Nobel’s generosity I owe sincerest thanks to them as well as to him.

The goddess of learning is fabled to have sprung full-grown from the brain of Zeus, but it is seldom that a scientific conception is born in its final form, or owns a single parent. More often it is the product of a series of minds, each in turn modifying the ideas of those that came before, and providing material for those that come after. The electron is no exception.

Although Faraday does not seem to have realized it, his work on electrolysis, by showing the unitary character of the charges on atoms in solution, was the first step. Clerk Maxwell in 1873 used the phrase a “molecule of electricity” and von Helmholtz in 1881 speaking of Faraday’s work said “If we accept the hypothesis that elementary substances are composed of atoms, we cannot well avoid concluding that electricity also is divided into elementary portions which behave like atoms of electricity.” The hypothetical atom received a name in the same year when Johnstone Stoney of Dublin christened it “electron”, but so far the only property implied was an electron charge.

The last year of the nineteenth century saw the electron take a leading place amongst the conceptions of physics. It acquired not only mass but universality, it was not only electricity but an essential part of all matter. If among the many names associated with this advance I mention that of J.J. Thomson I hope you will forgive a natural pride. It is to the great work of Bohr that we owe the demonstration of the connection between electrons and Planck’s quantum which gave the electron a dynamics of its own. A few years later, Goudsmit and Uhlenbeck, following on an earlier suggestion by A.H. Compton showed that it was necessary to suppose that the electron had spin. Yet even with the properties of charge, mass, spin and a special mechanics to help it, the electron was unable to carry the burden of explaining the large and detailed mass of experimental data which had accumulated. L. de Broglie , working originally on a theory of radiation, produced as a kind of by-product the conception that any particle and in particular an electron, was associated with a system of waves. It is with these waves, formulated more precisely by Schrödinger, and modified by Dirac to cover the idea of spin, that the rest of my lecture will deal.

The first published experiments to confirm de Broglie’s theory were those of Davisson and Germer, but perhaps you will allow me to describe instead those to which my pupils and I were led by de Broglie’s epoch-making conception.

A narrow beam of cathode rays was transmitted through a thin film of matter. In the earliest experiment of the late Mr. Reid this film was of celluloid, in my own experiment of metal. In both, the thickness was of the order of 10 -6 cm. The scattered beam was received on a photographic plate normal to the beam, and when developed showed a pattern of rings, recalling optical halos and the Debye -Scherrer rings well known in the corresponding experiment with X-rays. An interference phenomenon is at once suggested. This would occur if each atom of the film scattered in phase a wavelet from an advancing wave associated with the electrons forming the cathode rays. Since the atoms in each small crystal of the metal are regularly spaced, the phases of the wavelets scattered in any fixed direction will have a definite relationship to one another. In some directions they will agree in phase and build up a strong scattered wave, in others they will destroy one another by interference. The strong waves are analogous to the beams of light diffracted by an optical grating. At the time, the arrangement of the atoms in celluloid was not known with certainty and only general conclusions could be drawn, but for the metals it had been determined previously by the use of X-rays. According to de Broglie’s theory the wavelength associated with an electron is h/mv which for the electrons used (cathode rays of 20 to 60,000 volts energy) comes out from 8 X 10 -9 to 5 X 10 -9 cm. I do not wish to trouble you with detailed figures and it will be enough to say that the patterns on the photographic plates agreed quantitatively, in all cases, with the distribution of strong scattered waves calculated by the method I have indicated. The agreement is good to the accuracy of the experiments which was about 1%. There is no adjustable constant, and the patterns reproduce not merely the general features of the X-ray patterns but details due to special arrangements of the crystals in the films which were known to occur from previous investigation by X-rays. Later work has amply confirmed this conclusion, and many thousands of photographs have been taken in my own and other laboratories without any disagreement with the theory being found. The accuracy has increased with the improvement of the apparatus, perhaps the most accurate work being that of v. Friesen of Uppsala who has used the method in a precision determination of e in which he reaches an accuracy of I in 1,000.

Before discussing the theoretical implications of these results there are two modifications of the experiments which should be mentioned. In the one, the electrons after passing through the film are subject to a uniform magnetic field which deflects them. It is found that the electrons whose impact on the plate forms the ring pattern are deflected equally with those which have passed through holes in the film. Thus the pattern is due to electrons which have preserved unchanged the property of being deflected by a magnet. This distinguishes the effect from anything produced by X-rays and shows that it is a true property of electrons. The other point is a practical one, to avoid the need for preparing the very thin films which are needed to transmit the electrons, an apparatus has been devised to work by reflection, the electrons striking the diffracting surface at a small glancing angle. It appears that in many cases the patterns so obtained are really due to electrons transmitted through small projections on the surface. In other cases, for example when the cleavage surface of a crystal is used, true reflection occurs from the Bragg planes.

The theory of de Broglie in the form given to it by Schrödinger is now known as wave mechanics and is the basis of atomic physics. It has been applied to a great variety of phenomena with success, but owing largely to mathematical difficulties there are not many cases in which an accurate comparison is possible between theory and experiment. The diffraction of fast electrons by crystals is by far the severest numerical test which has been made and it is therefore important to see just what conclusions the excellent agreement between theory and these experiments permits us to draw.

The calculations so far are identical with those in the corresponding case of the diffraction of X-rays. The only assumption made in determining the directions of the diffracted beams is that we have to deal with a train of wave of considerable depth and with a plane wave-front extending over a considerable number of atoms. The minimum extension of the wave system sideways and frontways can be found from the sharpness of the lines. Taking v. Friesen’s figures, it is at least 225 waves from back to front over a front of more than 200 Å each way.

But the real trouble comes when we consider the physical meaning of the waves. In fact, as we have seen, the electrons blacken the photographic plate at those places where the waves would be strong. Following Bohr, Born, and Schrödinger, we can express this by saying that the intensity of the waves at any place measures the probability of an electron manifesting itself there. This view is strengthened by measurements of the relative intensities of the rings, which agree well with calculations by Mott based on Schrödinger’s equation. Such a view, however successful as a formal statement is at variance with all ordinary ideas. Why should a particle appear only in certain places associated with a set of waves? Why should waves produce effects only through the medium of particles? For it must be emphasized that in these experiments each electron only sensitizes the photographic plate in one minute region, but in that region it has the same powers of penetration and photographic action as if it had never been diffracted. We cannot suppose that the energy is distributed throughout the waves as in a sound or water wave, the wave is only effective in the one place where the electron appears. The rest of it is a kind of phantom. Once the particle has appeared the wave disappears like a dream when the sleeper wakes. Yet the motion of the electron, unlike that of a Newtonian particle, is influenced by what happens over the whole front of the wave, as is shown by the effect of the size of the crystals on the sharpness of the patterns. The difference in point of view is fundamental, and we have to face a break with ordinary mechanical ideas. Particles have not a unique track, the energy in these waves is not continuously distributed, probability not determinism governs nature.

But while emphasizing this fundamental change in outlook, which I believe to represent an advance in physical conceptions, I should like to point out several ways in which the new phenomena fit the old framework better than is often realized. Take the case of the influence of the size of the crystals on the sharpness of the diffracted beams, which we have just mentioned. On the wave theory it is simply an example of the fact that a diffraction grating with only a few lines has a poor resolving power. Double the number of the lines and the sharpness of the diffracted beams is doubled also. However if there are already many lines, the angular change is small. But imagine a particle acted on by the material which forms the slits of the grating, and suppose the forces such as to deflect it into one of the diffracted beams. The forces due to the material round the slits near the one through which it passes will be the most important, an increase in the number of slits will affect the motion but the angular deflection due to adding successive slits will diminish as the numbers increase. The law is of a similar character, though no simple law of force would reproduce the wave effect quantitatively.

Similarly for the length of the wave train. If this were limited by a shutter moving so quickly as to let only a short wave train pass through, the wave theory would require that the velocity of the particle would be uncertain over a range increasing with the shortness of the wave train, and corresponding to the range of wavelengths shown by a Fourier analysis of the train. But the motion of the shutter might well be expected to alter the velocity of a particle passing through, just before it closed.

Again, on the new view it is purely a matter of chance in which of the diffracted beams of different orders an electron appears. If the phenomenon were expressed as the classical motion of a particle, this would have to depend on the initial motion of the particle, and there is no possibility of determining this initial motion without disturbing it hopelessly. There seems no reason why those who prefer it should not regard the diffraction of electrons as the motion of particles governed by laws which simulate the character of waves, but besides the rather artificial character of the law of motion, one has to ascribe importance to the detailed initial conditions of the motion which, as far as our present knowledge goes, are necessarily incapable of being determined. I am predisposed by nature in favour of the most mechanical explanations possible, but I feel that this view is rather clumsy and that it might be best, as it is certainly safer, to keep strictly to the facts and regard the wave equation as merely a way of predicting the result of experiments. Nevertheless, the view I have sketched is often a help in thinking of these problems. We are curiously near the position which Newton took over his theory of optics, long despised but now seen to be far nearer the truth than that of his rivals and successors.

“Those that are averse from assenting to any new Discoveries, but such as they can explain by an Hypothesis, may for the present suppose, that as Stones by falling upon water put the Water into an undulating Motion, and all Bodies by percussion excite vibrations in the Air: so the Rays of Light, by impinging on any refracting or reflecting Surface, excite vibrations in the refracting or reflecting Medium or Substance, much after the manner that vibrations are propagated in the Air for causing Sound, and move faster than the Rays so as to overtake them; and that when any Ray is in that part of the vibration which conspires with its Motion, it easily breaks through a refracting Surface, but when it is in the contrary part of the vibration which impedes its Motion, it is easily reflected; and, by consequence, that every Ray is successively disposed to be easily reflected, or easily transmitted, by every vibration which overtakes it. But whether this Hypothesis be true or false I do not here consider.”

Although the experiments in diffraction confirm so beautifully the de Broglie-Schrödinger wave theory, the position is less satisfactory as regards the extended theory due to Dirac. On this theory the electron possesses magnetic properties and the wave requires four quantities instead of one for its specification. This satisfies those needs of spectroscopy which led to the invention of the spinning electron. It suggests however that electronic waves could be polarized and that the polarized waves might interact with matter in an anisotropic manner. In fact detailed calculations by Mott indicate that if Dirac electrons of 140 kV energy are scattered twice through 90° by the nuclei of gold atoms the intensity of the scattered beam will differ by 16% according to whether the two scatterings are in the same or in opposite directions. Experiments by Dymond and by myself have established independently that no effect of this order of magnitude exists, when the scattering is done by gold foils. While there is a slight possibility that the circumnuclear electrons, or the organization of the atoms into crystals might effect the result, it seems very unlikely. Some of the theorists have arrived at results conflicting with Mott, but I understand that their work has been found to contain errors. At present there seems no explanation of this discrepancy which throws doubt on the validity of the Dirac equations in spite of their success in predicting the positive electron.

I should be sorry to leave you with the impression that electron diffraction was of interest only to those concerned with the fundamentals of physics. It has important practical applications to the study of surface effects. You know how X-ray diffraction has made it possible to determine the arrangement of the atoms in a great variety of solids and even liquids. X-rays are very penetrating, and any structure peculiar to the surface of a body will be likely to be overlooked, for its effect is swamped in that of the much greater mass of underlying material. Electrons only affect layers of a few atoms, or at most tens of atoms, in thickness, and so are eminently suited for the purpose. The position of the beams diffracted from a surface enables us, at least in many cases, to determine the arrangement of the atoms in the surface. Among the many cases which have already been studied I have only time to refer to one, the state of the surface of polished metals. Many years ago Sir George Beilby suggested that this resembled a supercooled liquid which had flowed under the stress of polishing. A series of experiments by electron diffraction carried out at the Imperial College in London has confirmed this conclusion. The most recent work due to Dr. Cochrane has shown that though this amorphous layer is stable at ordinary temperature as long as it remains fixed to the mass of the metal, it is unstable when removed, and recrystalizes after a few hours. Work by Professor Finch on these lines has led to valuable conclusions as to the wear on the surfaces of cylinders and pistons in petrol engines.

It is in keeping with the universal character of physical science that this single small branch of it should touch on the one hand on the fundamentals of scientific philosophy and on the other, questions of everyday life.

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Scientific Biographies

Joseph John “J. J.” Thomson

In 1897 Thomson discovered the electron and then went on to propose a model for the structure of the atom. His work also led to the invention of the mass spectrograph.

The British physicist Joseph John “J. J.” Thomson (1856–1940) performed a series of experiments in 1897 designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by many scientists at the time.

Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of “bodies much smaller than atoms” (electrons) that he calculated as having a very large value for the charge-to-mass ratio. Later he estimated the value of the charge itself.

Structure of the Atom and Mass Spectrography

In 1904 Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. His efforts to estimate the number of electrons in an atom from measurements of the scattering of light, X, beta, and gamma rays initiated the research trajectory along which his student Ernest Rutherford moved.

Thomson’s last important experimental program focused on determining the nature of positively charged particles. Here his techniques led to the development of the mass spectrograph. His assistant, Francis Aston, developed Thomson’s instrument further and with the improved version was able to discover isotopes—atoms of the same element with different atomic weights—in a large number of nonradioactive elements.

Early Life and Education

Ironically, Thomson—great scientist and physics mentor—became a physicist by default. His father intended him to be an engineer, which in those days required an apprenticeship, but his family could not raise the necessary fee. Instead young Thomson attended Owens College, Manchester, which had an excellent science faculty. He was then recommended to Trinity College, Cambridge, where he became a mathematical physicist.

J. J. Thomson (left) and Ernest Rutherford in the 1930s.

In 1884 he was named to the prestigious Cavendish Professorship of Experimental Physics at Cambridge, although he had personally done very little experimental work. Even though he was clumsy with his hands, he had a genius for designing apparatus and diagnosing its problems. He was a good lecturer, encouraged his students, and devoted considerable attention to the wider problems of science teaching at university and secondary levels.

Ties to the Chemical Community

Of all the physicists associated with determining the structure of the atom, Thomson remained most closely aligned to the chemical community. His nonmathematical atomic theory—unlike early quantum theory—could also be used to account for chemical bonding and molecular structure (see Gilbert Newton Lewis and Irving Langmuir ). In 1913 Thomson published an influential monograph urging chemists to use the mass spectrograph in their analyses.

A Nobel Prize

Thomson received various honors, including the Nobel Prize in Physics in 1906 and a knighthood in 1908. He also had the great pleasure of seeing several of his close associates receive their own Nobel Prizes, including Rutherford in chemistry (1908) and Aston in chemistry (1922).

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JJ Thompson’s Discovery of Electron: Cathode Ray Tube Experiment Explained

JJ Thomson discovered the electron in 1897 and there are tons of videos about it. However, most videos miss what JJ Thomson himself said was the motivating factor: a debate about how cathode rays move. Want to know not only how but why electrons were discovered?

The start of jj thomson, how thomson discovered electrons: trials and errors, thomson’s conclusion.

A short history of Thomson: Joseph John Thomson, JJ on papers, to friends, and even to his own son [1] , was born in Lancashire, England to a middle class bookseller. When he was 14 years old, Thomson planned to get an apprenticeship to a locomotive engineer but it had a long waiting list, so, he applied to and was accepted at that very young age to Owen’s college.

Thompson later recalled that, “the authorities at Owens College thought my admission was such a scandal – I expect they feared that students would soon be coming in perambulators – that they passed regulations raising the minimum age for admission, so that such a catastrophe should not happen again.

[2] ” While in school, his father died, and his family didn’t have enough money for the apprenticeship. Instead, he relied on scholarships at universities – ironically leading him to much greater fame in academia. In 1884, at the tender age of 28, Thomson applied to be the head of the Cavendish Research Institute.

He mostly applied as a lark and was as surprised as anyone to actually get the position! “I felt like a fisherman who…had casually cast a line in an unlikely spot and hooked a fish much too heavy for him to land. [3] ” Suddenly, he had incredible resources, stability and ability to research whatever he wished.

He ended up having an unerring ability to pinpoint interesting phenomena for himself and for others. In fact, a full eight of his research assistants and his son eventually earned Nobel Prizes, but, of course, like Thomson’s own Nobel Prize, that was in the future.

Why did J. J. Thomson discover the electron in 1897? Well, according to Thomson: “the discovery of the electron began with an attempt to explain the discrepancy between the behavior of cathode rays under magnetic and electric forces [4] .” What did he mean by that?

Well, a cathode ray, or a ray in a vacuum tube that emanates from the negative electrode, can be easily moved with a magnet. This gave a charismatic English chemist named William Crookes the crazy idea that the cathode ray was made of charged particles in 1879!

However, 5 years later, a young German scientist named Heinrich Hertz found that he could not get the beam to move with parallel plates, or with an electric field. Hertz decided that Crookes was wrong, if the cathode ray was made of charged particles then it should be attracted to a positive plate and repulsed from a negative plate.

Ergo, it couldn’t be particles, and Hertz decided it was probably some new kind of electromagnetic wave, like a new kind of ultraviolet light. Further, in 1892, Hertz accidentally discovered that cathode rays could tunnel through thin pieces of metal, which seemed like further proof that Crookes was so very wrong.

Then, in December of 1895, a French physicist named Jean Perrin used a magnet to direct a cathode ray into and out of an electroscope (called a Faraday cylinder) and measured its charge. Perrin wrote, “the Faraday cylinder became negatively charged when the cathode rays entered it, and only when they entered it; the cathode rays are thus charged with negative electricity .

[5] ” This is why JJ Thomson was so confused, he felt that Perrin had, “conclusive evidence that the rays carried a charge of negative electricity” except that, “Hertz found that when they were exposed to an electric force they were not deflected at all.” What was going on?

In 1896, Thomson wondered if there might have been something wrong with Hertz’s experiment with the two plates. Thomson knew that the cathode ray tubes that they had only work if there is a little air in the tube and the amount of air needed depended on the shape of the terminals.

Thomson wondered if the air affected the results. Through trial and error, Thomson found he could get a “stronger” beam by shooting it through a positive anode with a hole in it. With this system he could evacuate the tube to a much higher degree and, if the vacuum was good enough, the cathode ray was moved by electrically charged plates, “just as negatively electrified particles would be.

[6] ” (If you are wondering why the air affected it, the air became ionized in the high electric field and became conductive. The conductive air then acted like a Faraday cage shielding the beam from the electric field.)

As stated before, Heinrich Hertz also found that cathode rays could travel through thin solids. How could a particle do that? Thomson thought that maybe particles could go through a solid if they were moving really, really fast. But how to determine how fast a ray was moving?

Thomson made an electromagnetic gauntlet. First, Thomson put a magnet near the ray to deflect the ray one-way and plates with electric charge to deflect the ray the other way. He then added or reduced the charge on the plates so that the forces were balanced and the ray went in a straight line.

He knew that the force from the magnet depended on the charge of the particle, its speed and the magnetic field (given the letter B). He also knew that the electric force from the plates only depended on the charge of the particle and the Electric field. Since these forces were balanced, Thomson could determine the speed of the particles from the ratio of the two fields.

Thomson found speeds as big as 60,000 miles per second or almost one third of the speed of light. Thomson recalled, “In all cases when the cathode rays are produced their velocity is much greater than the velocity of any other moving body with which we are acquainted. [7] ”

Thomson then did something even more ingenious; he removed the magnetic field. Now, he had a beam of particles moving at a known speed with a single force on them. They would fall, as Thomson said, “like a bullet projected horizontally with a velocity v and falling under gravity [8] ”.

Note that these “bullets” are falling because of the force between their charge and the charges on the electric plates as gravity is too small on such light objects to be influential. By measuring the distance the bullets went he could determine the time they were in the tube and by the distance they “fell” Thomson could determine their acceleration.

Using F=ma Thomson determine the ratio of the charge on the particle to the mass (or e/m). He found some very interesting results. First, no matter what variables he changed in the experiment, the value of e/m was constant. “We may… use any kind of substance we please for the electrodes and fill the tube with gas of any kind and yet the value of e/m will remain the same.

[9] ” This was a revolutionary result. Thomson concluded that everything contained these tiny little things that he called corpuscles (and we call electrons). He also deduced that the “corpuscles” in one item are exactly the same as the “corpuscles” in another. So, for example, an oxygen molecule contains the same kind of electrons as a piece of gold! Atoms are the building blocks of matter but inside the atoms (called subatomic) are these tiny electrons that are the same for everything .

The other result he found was that the value of e/m was gigantic, 1,700 times bigger than the value for a charged Hydrogen atom, the object with the largest value of e/m before this experiment. So, either the “corpuscle” had a ridiculously large charge or it was, well, ridiculously small.

A student of Thomson’s named C. T. R. Wilson had experimented with slowly falling water droplets that found that the charge on the corpuscles were, to the accuracy of the experiment, the same as the charge on a charged Hydrogen atom! Thomson concluded that his corpuscles were just very, very, tiny, about 1,700 times smaller then the Hydrogen atom [1] . These experiments lead Thomson to come to some interesting conclusions:

Electrons are in everything and are well over a thousand times smaller then even the smallest atom.
Benjamin Franklin thought positive objects had too much “electrical fire” and negative had too little. Really, positive objects have too few electrons and negative have too many. Oops.
Although since Franklin, people thought current flowed from the positive side to the negative, really, the electrons are flowing the other way. When a person talks about “current” that flows from positive to negative they are talking about something that is not real! True “electric current” flows from negative to positive and is the real way the electrons move. [although by the time that people believed J.J. Thomson, it was too late to change our electronics, so people just decided to stick with “current” going the wrong way!]
Since electrons are tiny and in everything but most things have a neutral charge, and because solid objects are solid, the electrons must be swimming in a sea or soup of positive charges. Like raisons in a raison cookie.

The first three are still considered correct over one hundred years later. The forth theory, the “plum pudding model” named after a truly English “desert” with raisins in sweet bread that the English torture people with during Christmas, was proposed by Thomson in 1904.

In 1908, a former student of Thomson’snamed Ernest Rutherford was experimenting with radiation, and inadvertently demolished the “plum pudding model” in the process. However, before I can get into Rutherford’s gold foil experiment, I first want to talk about what was going on in France concurrent to Thomson’s experiments.

This is a story of how a new mother working mostly in a converted shed discovered and named the radium that Rutherford was experimenting with. That woman’s name was Marie Sklodowska Curie, and that story is next time on the Lightning Tamers.

[1] the current number is 1,836 but Thomson got pretty close

[1] p 14 “Flash of the Cathode Rays: A History of JJ Thomson’s Electron” Dahl

[2] Thompson, J.J. Recollections and Reflections p. 2 Referred to in Davis & Falconer JJ. Thompson and the Discovery of the Electron 2002 p. 3

[3] Thomson, Joseph John Recollections and Reflections p. 98 quoted in Davis, E.A & Falconer, Isabel JJ Thomson and the Discovery of the Electron 2002 p. 35

[4] Thomson, JJ Recollections and Reflections p. 332-3

[5] “New Experiments on the Kathode Rays” Jean Perrin, December 30, 1985 translation appeared in Nature, Volume 53, p 298-9, January 30, 1896

[6] Nobel Prize speech?

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Cathode Ray Experiment

The electric experiment by j.j. thomson.

J. J. Thomson was one of the great scientists of the 19th century; his inspired and innovative cathode ray experiment greatly contributed to our understanding of the modern world.

This article is a part of the guide:

Ben Franklin Kite
Physics Experiments
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1 Physics Experiments
2 Ben Franklin Kite
3 Brownian Movement
4 Cathode Ray Experiment

Like most scientists of that era, he inspired generations of later physicists, from Einstein to Hawking .

His better-known research proved the existence of negatively charged particles, later called electrons, and earned him a deserved Nobel Prize for physics. This research led to further experiments by Bohr and Rutherford, leading to an understanding of the structure of the atom.

What is a Cathode Ray Tube?

Even without consciously realizing it, most of us are already aware of what a cathode ray tube is.

Look at any glowing neon sign or any ‘old-fashioned’ television set, and you are looking at the modern descendants of the cathode ray tube.

Physicists in the 19th century found out that if they constructed a glass tube with wires inserted in both ends, and pumped out as much of the air as they could, an electric charge passed across the tube from the wires would create a fluorescent glow. This cathode ray also became known as an ‘electron gun’.

Later and improved cathode ray experiments found that certain types of glass produced a fluorescent glow at the positive end of the tube. William Crookes discovered that a tube coated in a fluorescing material at the positive end, would produce a focused ‘dot’ when rays from the electron gun hit it.

With more experimentation, researchers found that the ‘cathode rays’ emitted from the cathode could not move around solid objects and so traveled in straight lines, a property of waves. However, other researchers, notably Crookes, argued that the focused nature of the beam meant that they had to be particles.

Physicists knew that the ray carried a negative charge but were not sure whether the charge could be separated from the ray. They debated whether the rays were waves or particles, as they seemed to exhibit some of the properties of both. In response, J. J. Thomson constructed some elegant experiments to find a definitive and comprehensive answer about the nature of cathode rays.

Thomson’s First Cathode Ray Experiment

Thomson had an inkling that the ‘rays’ emitted from the electron gun were inseparable from the latent charge, and decided to try and prove this by using a magnetic field.

His first experiment was to build a cathode ray tube with a metal cylinder on the end. This cylinder had two slits in it, leading to electrometers, which could measure small electric charges.

He found that by applying a magnetic field across the tube, there was no activity recorded by the electrometers and so the charge had been bent away by the magnet. This proved that the negative charge and the ray were inseparable and intertwined.

Thomson's Cathode Ray Second Experiment

Like all great scientists, he did not stop there, and developed the second stage of the experiment, to prove that the rays carried a negative charge. To prove this hypothesis, he attempted to deflect them with an electric field.

Earlier experiments had failed to back this up, but Thomson thought that the vacuum in the tube was not good enough, and found ways to improve greatly the quality.

For this, he constructed a slightly different cathode ray tube, with a fluorescent coating at one end and a near perfect vacuum. Halfway down the tube were two electric plates, producing a positive anode and a negative cathode, which he hoped would deflect the rays.

As he expected, the rays were deflected by the electric charge, proving beyond doubt that the rays were made up of charged particles carrying a negative charge. This result was a major discovery in itself, but Thomson resolved to understand more about the nature of these particles.

Thomson's Third Experiment

The third experiment was a brilliant piece of scientific deduction and shows how a series of experiments can gradually uncover truths.

Many great scientific discoveries involve performing a series of interconnected experiments, gradually accumulating data and proving a hypothesis .

He decided to try to work out the nature of the particles. They were too small to have their mass or charge calculated directly, but he attempted to deduce this from how much the particles were bent by electrical currents, of varying strengths.

Thomson found out that the charge to mass ratio was so large that the particles either carried a huge charge, or were a thousand times smaller than a hydrogen ion. He decided upon the latter and came up with the idea that the cathode rays were made of particles that emanated from within the atoms themselves, a very bold and innovative idea.

Later Developments

Thomson came up with the initial idea for the structure of the atom, postulating that it consisted of these negatively charged particles swimming in a sea of positive charge. His pupil, Rutherford, developed the idea and came up with the theory that the atom consisted of a positively charged nucleus surrounded by orbiting tiny negative particles, which he called electrons.

Quantum physics has shown things to be a little more complex than this but all quantum physicists owe their legacy to Thomson. Although atoms were known about, as apparently indivisible elementary particles, he was the first to postulate that they had a complicated internal structure.

Thomson's greatest gift to physics was not his experiments, but the next generation of great scientists who studied under him, including Rutherford, Oppenheimer and Aston. These great minds were inspired by him, marking him out as one of the grandfathers of modern physics.

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suggested that they do. He advanced the idea that cathode rays are really streams of very small pieces of atoms. Three experiments led him to this.: of an 1895 experiment by Jean Perrin, Thomson built a ending in a pair of metal cylinders with a slit in them. These cylinders were in turn connected to an electrometer, a device for catching and measuring electrical charge. Perrin had found that cathode rays deposited an electric charge. Thomson wanted to see if, by bending the rays with a magnet, he could separate the charge from the rays. He found that when the rays entered the slit in the cylinders, the electrometer measured a large amount of negative charge. The electrometer did not register much electric charge if the rays were bent so they would not enter the slit. As Thomson saw it, the negative charge and the cathode rays must somehow be stuck together: you cannot separate the charge from the rays.
.		when physicists tried to bend cathode rays with an electric field. Now Thomson thought of a new approach. A charged particle will normally curve as it moves through an electric field, but not if it is surrounded by a conductor (a sheath of copper, for example). Thomson suspected that the traces of gas remaining in the tube were being turned into an electrical conductor by the cathode rays themselves. To test this idea, he took great pains to extract nearly all of the gas from a tube, and found that now the cathode rays did bend in an electric field after all.
	from these two experiments, "I can see no escape from the conclusion that [cathode rays] are charges of negative electricity carried by particles of matter." But, he continued, "What are these particles? are they atoms, or molecules, or matter in a still finer state of subdivision?"
.		sought to determine the basic properties of the particles. Although he couldn't measure directly the mass or the electric charge of such a particle, he could measure how much the rays were bent by a magnetic field, and how much energy they carried. From this data he could calculate the of the mass of a particle to its electric charge ( / ). He collected data using a variety of tubes and using different gases.
.		Just as Emil Wiechert had reported earlier that year, the mass-to-charge ratio for cathode rays turned out to be far smaller than that of a charged hydrogen atom--more than one thousand times smaller. Either the cathode rays carried an enormous charge (as compared with a charged atom), or else they were amazingly light relative to their charge. was settled by . Experimenting on how cathode rays penetrate gases, he showed that if cathode rays were particles they had to have a mass very much smaller than the mass of any atom. The proof was far from conclusive. But experiments by others in the next two years yielded an independent measurement of the value of the charge ( ) and confirmed this remarkable conclusion.
the hypothesis that "we have in the cathode rays matter in a new state, a state in which the subdivision of matter is carried very much further than in the ordinary gaseous state: a state in which all matter... is of one and the same kind; this matter being the substance from which all the chemical elements are built up."
1897 Experiments

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This Day In History : April 30

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British physicist J.J. Thomson announces the discovery of electrons

On April 30, 1897, British physicist J.J. Thomson announced his discovery that atoms were made up of smaller components . This finding revolutionized the way scientists thought about the atom and had major ramifications for the field of physics. Though Thomson referred to them as "corpuscles," what he found is more commonly known today as the electron.

Mankind had already discovered electric current and harnessed it to great effect, but scientists had not yet observed the makeup of atoms. Thomson, a highly-respected professor at Cambridge, determined the existence of electrons by studying cathode rays. He concluded that the particles making up the rays were 1,000 times lighter than the lightest atom, proving that something smaller than atoms existed. Thomson likened the composition of atoms to plum pudding, with negatively charged "corpuscles" dotted throughout a positively-charged field.

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The plum pudding analogy was disproved by Ernest Rutherford, a student and collaborator of Thomson’s, in Thomson's lab at Cambridge in 1910. Rutherford's conclusion that the positive charge of an atom resides in its nucleus established the model of the atom as we know it today. In addition to winning his own Nobel Prize, Thomson employed six research assistants who went on to win Nobel Prizes in physics and two, including Rutherford, who won Nobel Prizes for chemistry. His son, George Paget Thomson, also won a Nobel Prize for his study of electrons. Combined with his own research, the network of atomic researchers Thomson cultivated gave humanity a new and detailed understanding of the smallest building blocks of the universe.

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Thomson's Discovery of The Electron

This topic is part of the HSC Physics course under the section Structure of The Atom .

HSC Physics Syllabus

investigate, assess and model the experimental evidence supporting the existence and properties of the electron, including:

How Did Thomson Discover The Electron?

This video describes Thomson's experiment that led to the discovery of the first subatomic particle – the electron.

J.J. Thomson’s Experiment

Thomson's experiment involved manipulating the path of a cathode ray using a uniform electric field and a uniform magnetic field. Thomson's experiment obtained a value for the charge to mass ratio of cathode rays, which proved their particle nature.

In the first part of Thomson's experiment, a pair of charged metal plates was used to create a uniform electric field. When a cathode ray travelled through this field, it was deflected towards the positive plate.

Next, Thomson applied a uniform magnetic field using current-carrying coils. The direction of this magnetic field was perpendicular to the electric field, and positioned such that it would cause the cathode ray to deflect downwards.

Thomson adjusted the strength of the magnetic field until the cathode travelled a straight path. When this occurred, the force acting on the cathode ray due to the electric field balanced the force due to the magnetic field.

$$F_E=F_B$$

$$qE=qvB\sin\theta$$

$$v=\frac{E}{B}$$

After a straight trajectory was achieved, the electric field was switched off. Under the influence of the magnetic field only, the cathode ray was deflected downwards. Here, the radius of the cathode's curved path can be analysed by considering centripetal force.

The centripetal force was provided by the force due to the magnetic field:

$$\frac{mv^2}{r}=qvB$$

$$\frac{mv}{r}=qB$$

Expressing v in terms of E and B

$$\frac{m(\frac{E}{B})}{r}=qB$$

$$\frac{q}{m}=\frac{E}{rB^2}$$

(We recommend understanding the derivation of the above equation to be able to provide mathematical support in exam responses)

Since the value of E , B and r were known to Thomson, the value of the charge to mass ratio of the cathode ray was calculated. This value was 1.76 x 10 11 C kg –1

Thomson replicated the experiment using cathodes made from different metals and under various conditions. He showed that the value of charge to mass ratio remained constant.

Thomson's Interpretation

Since an actual charge to mass ratio value was determined for cathode rays, Thomson proved that cathode rays do indeed have mass, and hence are negatively charged particles .

In addition, the constancy of the cathode ray's charge to mass ratio shows that these negatively charged particles are present in all matter. As a result, Thomson's experiment led to the discovery of the first subatomic particle – the electron.

The charge to mass ratio of electrons was shown to be 1800 times greater than that of hydrogen ions. Thomson assumed the magnitude of charge is equal for these particles, leading to the conclusion that the mass of an electron is 1800 times smaller than a hydrogen ion.

Thomson's Model of the Atom ('Plum Pudding' Model)

The discovery of the electron as a subatomic particle led to the development of Thomson's atomic model.

A simple representation of Thomson's atomic model

In Thomson's model of the atom, negatively charged electrons are dispersed in a positive mass due to electrostatic repulsion. The electrons are held together in the atom due to their attraction to the positive mass.

One major limitation of Thomson's model is the lack of explanation for the positive mass. This feature of the model was based on theory and lacked experimental evidence.

Thomson's model of the atom was shown to be incorrect in Geiger-Marsden's gold foil experiment .

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The world’s fastest microscope captures electrons down to the attosecond

By Andrew Paul

Posted on Aug 22, 2024 2:47 PM EDT

3 minute read

Electron microscopy has existed for nearly a century, but a record-breaking modern iteration finally achieved what physicists have waited decades to see—for the first time, a transmission electron microscope is capturing an electron with such clarity they can see its individual components. Researchers believe they have unlocked an entirely new realm of optical science they are now calling “attomicroscopy” that will influence the worlds of quantum physics , biology, and chemistry.

The breakthrough comes from a team led by experts at the University of Arizona and is detailed in a new study published August 21 in Science Advances . Mohammed Hassan, a UA associate professor of physics and optical sciences, likens transmission electron microscopes to a smartphone’s camera.

“When you get the latest version of a smartphone, it comes with a better camera,” Hassan said in an accompanying university statement on Wednesday. “… With this microscope, we hope the scientific community can understand the quantum physics behind how an electron behaves and how an electron moves.”

[Related: Winners of the 2023 Nobel Prize in physics measured electrons by the attosecond .]

While the original electron microscope arrived in the early 1930’s (there’s still a controversy to this day over who invented the very first one), scientists have relied on what are known as transmission electron microscopes since the 2000s. In these devices, objects are magnified millions of times their size far beyond what light microscopes can accomplish. This is due to their reliance on pulses of electron laser beams fired at a target. From there, extremely precise camera sensors and lenses image these atomic particles as they pass through the sample. The changes observed in a subject between these images is what is called a microscope’s temporal resolution. To increase the resolution, researchers have turned to speeding up those laser bursts down to attoseconds lasting just quintillionths of a second.

But even here, the problem is “attoseconds,” plural. If physicists ever hoped to capture a single electron frozen in place and detail its incomprehensibly fast subatomic reactions and interactions, they would need a transmission electron microscope capable of firing a single attosecond pulse. To make this a reality, researchers turned to the work pioneered by 2023’s winners of the Nobel Prize in Physics , who generated the first extreme ultraviolet radiation pulse, also measured in attoseconds. With that foundation, the team finally achieved that one-attosecond benchmark.

To do so, researchers developed and built a new microscope that splits its laser into a single electron pulse and two pulses of ultrashort light. The first light pulse, called a pump pulse, energizes a sample’s electrons. Next, what’s known as an optical gating pulse initiates, allowing an infinitesimal timeframe for a one-attosecond electron pulse to then emit from the microscope. Once the two ultrashort light pulses are properly synchronized, operators time the electron pulses to help capture atomic events at an attosecond-level temporal resolution.

“The improvement of the temporal resolution inside of electron microscopes has long been anticipated and the focus of many research groups,” Hassan said on Wednesday. “… For the first time, we can see pieces of the electron in motion.”

According to the study’s abstract, the attosecond microscope will allow physicists, optical scientists, and other experts to study electron motion in unprecedented detail and “directly connect it to the structural dynamics of matter in real-time and space domains.” This, they say, will hopefully pave the way for “real-life attosecond science applications in quantum physics, chemistry, and biology.”

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Freeze-frame: Researchers develop world's fastest microscope that can see electrons in motion

by University of Arizona

Freeze-frame: U of A researchers develop world's fastest microscope that can see electrons in motion

Imagine owning a camera so powerful it can take freeze-frame photographs of a moving electron—an object traveling so fast it could circle the Earth many times in a matter of a second. Researchers at the University of Arizona have developed the world's fastest electron microscope that can do just that.

They believe their work will lead to groundbreaking advancements in physics, chemistry, bioengineering, materials sciences and more.

"When you get the latest version of a smartphone, it comes with a better camera," said Mohammed Hassan, associate professor of physics and optical sciences .

"This transmission electron microscope is like a very powerful camera in the latest version of smart phones; it allows us to take pictures of things we were not able to see before—like electrons. With this microscope, we hope the scientific community can understand the quantum physics behind how an electron behaves and how an electron moves."

Hassan led a team of researchers in the departments of physics and optical sciences that published the research article "Attosecond electron microscopy and diffraction" in the Science Advances journal.

Hassan worked alongside Nikolay Golubev, assistant professor of physics; Dandan Hui, co-lead author and former research associate in optics and physics who now works at the Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences; Husain Alqattan, co-lead author, U of A alumnus and assistant professor of physics at Kuwait University; and Mohamed Sennary, a graduate student studying optics and physics.

A transmission electron microscope is a tool used by scientists and researchers to magnify objects up to millions of times their actual size in order to see details too small for a traditional light microscope to detect.

Instead of using visible light, a transmission electron microscope directs beams of electrons through whatever sample is being studied. The interaction between the electrons and the sample is captured by lenses and detected by a camera sensor in order to generate detailed images of the sample.

Ultrafast electron microscopes using these principles were first developed in the 2000's and use a laser to generate pulsed beams of electrons. This technique greatly increases a microscope's temporal resolution—its ability to measure and observe changes in a sample over time.

In these ultrafast microscopes, instead of relying on the speed of a camera's shutter to dictate image quality , the resolution of a transmission electron microscope is determined by the duration of electron pulses.

The faster the pulse, the better the image.

Ultrafast electron microscopes previously operated by emitting a train of electron pulses at speeds of a few attoseconds. An attosecond is one quintillionth of a second. Pulses at these speeds create a series of images, like frames in a movie—but scientists were still missing the reactions and changes in an electron that takes place in between those frames as it evolves in real time.

In order to see an electron frozen in place, U of A researchers, for the first time, generated a single attosecond electron pulse, which is as fast as electrons move, thereby enhancing the microscope's temporal resolution, like a high-speed camera capturing movements that would otherwise be invisible.

Hassan and his colleagues based their work on the Nobel Prize-winning accomplishments of Pierre Agostini, Ferenc Krausz and Anne L'Huilliere, who won the Novel Prize in Physics in 2023 after generating the first extreme ultraviolet radiation pulse so short it could be measured in attoseconds.

Using that work as a steppingstone, U of A researchers developed a microscope in which a powerful laser is split and converted into two parts—a very fast electron pulse and two ultra-short light pulses. The first light pulse, known as the pump pulse, feeds energy into a sample and causes electrons to move or undergo other rapid changes.

The second light pulse, also called the "optical gating pulse" acts like a gate by creating a brief window of time in which the gated, single attosecond electron pulse is generated. The speed of the gating pulse therefore dictates the resolution of the image. By carefully synchronizing the two pulses, researchers control when the electron pulses probe the sample to observe ultrafast processes at the atomic level.

"The improvement of the temporal resolution inside of electron microscopes has been long anticipated and the focus of many research groups—because we all want to see the electron motion," Hassan said.

"These movements happen in attoseconds. But now, for the first time, we are able to attain attosecond temporal resolution with our electron transmission microscope—and we coined it 'attomicroscopy.' For the first time, we can see pieces of the electron in motion."

Journal information: Science Advances

Provided by University of Arizona

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Open access
Published: 20 August 2024

CO-driven electron and carbon flux fuels synergistic microbial reductive dechlorination

Jingjing Wang ORCID: orcid.org/0009-0008-0753-1732 1 ,
Xiuying Li ORCID: orcid.org/0000-0003-3555-7418 1 ,
Huijuan Jin 1 ,
Shujing Yang 1 , 3 ,
Lian Yu 4 ,
Hongyan Wang 1 , 2 ,
Siqi Huang 1 , 2 ,
Hengyi Liao 1 , 2 ,
Xuhao Wang 1 , 2 ,
Jun Yan ORCID: orcid.org/0000-0001-6883-8529 1 &
Yi Yang ORCID: orcid.org/0000-0002-3519-5472 1 , 5

Microbiome volume 12 , Article number: 154 ( 2024 ) Cite this article

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Carbon monoxide (CO), hypothetically linked to prebiotic biosynthesis and possibly the origin of the life, emerges as a substantive growth substrate for numerous microorganisms. In anoxic environments, the coupling of CO oxidation with hydrogen (H 2 ) production is an essential source of electrons, which can subsequently be utilized by hydrogenotrophic bacteria (e.g., organohalide-respring bacteria). While Dehalococcoides strains assume pivotal roles in the natural turnover of halogenated organics and the bioremediation of chlorinated ethenes, relying on external H 2 as their electron donor and acetate as their carbon source, the synergistic dynamics within the anaerobic microbiome have received comparatively less scrutiny. This study delves into the intriguing prospect of CO serving as both the exclusive carbon source and electron donor, thereby supporting the reductive dechlorination of trichloroethene (TCE).

The metabolic pathway involved anaerobic CO oxidation, specifically the Wood-Ljungdahl pathway, which produced H 2 and acetate as primary metabolic products. In an intricate microbial interplay, these H 2 and acetate were subsequently utilized by Dehalococcoides , facilitating the dechlorination of TCE. Notably, Acetobacterium emerged as one of the pivotal collaborators for Dehalococcoides , furnishing not only a crucial carbon source essential for its growth and proliferation but also providing a defense against CO inhibition.

Conclusions

This research expands our understanding of CO’s versatility as a microbial energy and carbon source and unveils the intricate syntrophic dynamics underlying reductive dechlorination.

Graphical Abstract

Video Abstract

Introduction

Carbon monoxide (CO), presumed to be abundant in the prebiotic Earth, holds compelling evidence for its involvement in prebiotic synthesis and probably the origin of life. Early life on Earth thrived amidst high levels of CO exposure [ 1 , 2 , 3 ], a phenomenon traced back to the primordial atmospheric conditions that prevailed around 4 billion years ago when life first emerged. The Wood-Ljungdahl pathway (WLP), an ancient carbon fixation pathway consisting of the methyl and the carbonyl branches, is hypothesized to have played a pivotal role in the origin of life on ancient Earth as well as microbial energy conservation and carbon assimilation under anoxic conditions [ 4 , 5 , 6 ]. CO, serving as both a carbon and electron source, finds relevance for microorganisms utilizing WLP [ 7 , 8 ].

CO, once thought of as a toxic gas, has emerged as a fascinating and surprisingly versatile metabolic substrate for diverse microorganisms through both fermentative and respiratory pathways [ 8 ]. Certain aerobic bacteria, such as Oligotropha carboxidivorans , Ruegeria pomeroyi , and Mycobacterium smegmatis [ 9 ], are capable of oxidizing atmospheric CO, where CO serves as both electron donor and carbon source, with O 2 as the electron acceptor. Under anoxic conditions, CO is typically metabolized through fermentative pathways, with nickel-dependent CODHs (Ni-CODH) playing a crucial role in oxidizing CO to various products, including CO 2 plus H 2 , acetate, ethanol, or methane plus CO 2 [ 7 , 10 , 11 ]. Certain groups of microorganisms, such as sulfate-reducing bacteria and iron-reducing bacteria, employ respiratory metabolism to utilize CO. In this respiratory process, CO is oxidized to CO 2 with either SO 4 2− or Fe 3+ serving as the electron acceptor and subsequently being reduced to S 2− or Fe 2+ [ 7 , 12 ]. CO’s diverse metabolic pathways highlight the remarkable adaptability of microorganisms to different environmental conditions.

Organohalide-respiring bacteria (OHRB) not only gained recognition as crucial microorganisms for the bioremediation of chlorinated solvents, but it has also played pivotal roles in the natural turnover of halogenated organics [ 13 ]. Dehalococcoides mccartyi populations are obligate OHRB, and its noteworthy ability to convert the ubiquitous groundwater contaminants chlorinated ethenes (strains 195, FL2, BAV1, GT), chlorinated ethanes (strains 195, BAV1, VS, 11a), pentachlorophenol (strain JNA), chlorinated biphenyls (strain CG1), and chlorinated benzenes (strain CBDB1) to the low or non-toxic end products has made it a key player in environmental detoxification [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. While Dehalococcoides excel at detoxification, their own metabolic processes, specifically the incomplete WLP for methionine biosynthesis, can turn against them, leading to CO accumulation and potentially hindering their effectiveness [ 25 , 26 , 27 ]. The toxicity of CO, detrimental to Dehalococcoides strains, could be alleviated by other CO-utilizing bacteria within the microbial community (e.g., Desulfovibrio , Acetobacterium ) [ 10 , 27 , 28 , 29 ]. CO produced by Dehalococcoides may also serve as an energy source for anaerobically CO-oxidizing bacteria. In addition to protections offered by other microbes (e.g., fermenters, acetogens), Dehalococcoides thrives optimally in microbial communities by acquiring essential resources including the electron donor H 2 and carbon source acetate. For instance, the H 2 and acetate, generated through lactate fermentation by Desulfovibrio desulfuricans strain F1, were harnessed by Dehalococcoides strain CG1 for organohalide respiration, highlighting a synergistic interaction [ 30 ]. CO could have served as a more thermodynamically favorable “first” electron donor than H 2 [ 31 ] and a potential carbon source; nonetheless, evidence regarding on CO’s role in supporting reductive dechlorination remains rare. In contrast to OHRB, Acetobacterium dehalogenans utilizes chloromethane and produces acetate as a fermentation end product [ 32 , 33 , 34 ]. This distinction highlights the diverse metabolic strategies employed by microorganisms for dehalogenation. While Acetobacterium species are primarily known as acetogens that indirectly support dechlorination by providing essential cofactors like vitamin B 12 and acetate [ 35 , 36 , 37 , 38 ], some strains, such as Acetobacterium strain AG, have demonstrated the ability to directly debrominate polybrominated diphenyl ethers (PBDEs) under various growth conditions, including organic-carbon-free medium [ 37 ]. This finding expands the known capabilities of Acetobacterium in halogenated organic compound transformations.

CO is a naturally occurring compound in underground environments, potentially serving both as an electron donor and a carbon source for a variety of microorganisms. In this study, we hypothesize that CO could fuel reductive dechlorination within mixed microbial communities, specifically supporting the activities of OHRB (e.g., Dehalococcoides ). To test this hypothesis, we established microcosms using river sediment as a microbial source, exploring the potential of CO as a supportive factor for sustained dechlorination. Our investigations revealed that CO, even at concentrations exceeding 2.2 µM—previously deemed detrimental to Dehalococcoides growth [ 27 ]—effectively promoted the survival, growth, and enrichment of the key dechlorinator. These revelations carry substantial implications, shedding light on the conceivable role of CO as both electron donor and carbon source for diverse microorganisms inhabiting subterranean environments, including the less-recognized OHRB. Additionally, they underscore the significance of CO in facilitating the reductive dechlorination activities of OHRB beyond the scope previously acknowledged.

Materials and methods

Trichloroethylene (TCE) and cis -1,2-dichloroethylene ( c DCE) were purchased from Macklin Biochemical Co., Ltd (Shanghai, China). Vinyl chloride (VC) and ethene (both ≥ 99%) were purchased from Dalian Special Gases Co., Ltd (Dalian, China). H 2 , nitrogen (N 2 ), carbon dioxide (CO 2 ), and CO (all ≥ 99.999%) were purchased from Shuntai Special Gases Co., Ltd (Shenyang, China). All other chemicals used in this study were analytical grade or of higher purity.

Microcosm setup and enrichment cultures

Medium preparation and anaerobic cultivation were performed following established protocols [ 39 , 40 , 41 ]. Briefly, a reduced, bicarbonate-buffered mineral salt medium was boiled under an atmosphere of N 2 to remove dissolved oxygen, cooled down to room temperature, and then dispensed into serum bottles flushed with N 2 /CO 2 (80/20, v/v). Sediment samples were collected from a location (41° 39′ 46″ N, 123° 6′ 20″ E) at Xi River, Shenyang, Liaoning Province, China, as described [ 42 ]. Microcosms were constructed inside an anoxic chamber (Coy Laboratory Inc., MI, USA) filled with N 2 /H 2 (97/3, v/v). An aliquot of 2 mL sediment sludge was pipetted into 120-mL glass serum bottles prefilled with 80 mL of medium mentioned above as described [ 40 , 43 ]. Bottles were sealed with butyl rubber stoppers (Fushiyuan rubber and plastic products factory, Shenzhen, Guangdong, China) and crimped with aluminum caps (Hongpu Instrument Technology, Ningbo, Zhejiang, China). Initially, acetate (5 mM) was provided as the carbon source, and CO (2 mL) was provided as the electron donor. In the incubation period, CO was added to several doses (2 mL each). Neat TCE (3 µL, ca. 0.3 mM or 43.4 mg/L aqueous phase concentration) was added as the electron acceptor. All bottles were amended with Wolin vitamin mix [ 44 ]. Following the complete dechlorination of TCE to ethene, 1 mL culture suspension was transferred into a fresh medium following the same procedures (Fig. S 1 ). The bottles were incubated statically in the dark at 30 °C. Microcosms and enrichment cultures were established in triplicate bottles. Cultures amended without CO or with H 2 as the electron donor served as controls.

Sequencing, assembly, and binning

Metagenome sequencing was performed by Novogene Co., Ltd. (Beijing, China). DNA samples were extracted from the fourth transfer enrichment cultures with CO as both carbon source and electron donor using the CTAB protocol [ 45 ]. DNA degradation and potential contamination were monitored on 1% agarose gels. DNA concentration was measured using Qubit® dsDNA Assay Kit in Qubit® 2.0 Fluorometer (Life Technologies, CA, USA). Sequencing libraries were generated using NEBNext® Ultra™ DNA Library Prep Kit for Illumina (NEB, USA) following manufacturer’s recommendations, and index codes were added to attribute sequences to each sample. The clustering of the index-coded samples was performed on a cBot Cluster Generation System. After cluster generation, the library preparations were sequenced on an Illumina Hiseq platform, and paired-end reads were generated. Raw sequence data were processed with Readfq v8 ( https://github.com/cjfields/readfq ) to acquire the filtered sequence data for subsequent analysis. After being trimmed and filtered, the resulting 35,338,878 paired-end reads were assembled using the JGI Metagenome Assembly Pipeline ( https://github.com/kbaseapps/jgi_mg_assembly ) [ 46 ]. Metagenomic short-read profiling and taxonomic classification were performed using Kaiju v1.7.3 [ 47 ]. Metagenomic contigs were classified with Maxbin2 v2.2.4 [ 48 ]. The metagenome-assembled genomes (MAGs) were assessed with CheckM [ 49 ] using default settings for completeness and contamination evaluation. High-quality MAGs that included the draft genome sequence of a Dehalococcoides strain, designated as strain CO, were annotated using BV-BRC v3.29.20 ( https://www.bv-brc.org/ ) and RAST v2.0 ( https://rast.nmpdr.org/ ) with default parameters. The procedures for DNA extraction, amplicon sequencing, Sanger sequencing, PCR, and qPCR are elaborated in the Supplementary Information (SI).

Analytical methods

Ethene, methane, and chlorinated compounds were analyzed using an Agilent 7890B gas chromatography (GC) equipped with an Agilent 7697A automatic headspace sampler (Agilent Technologies, Santa Clara, CA, USA), a flame ionization detector (FID) (method detection limit ~ 0.2 µM) and an Agilent DB-624 capillary column (60 m length × 0.32 mm inner diameter × 1.8 μm film thickness) as described [ 40 ]. Oven temperature was initially held at 60 °C for 2 min, increased to 200 °C at 25 °C/ min, and held at 200 °C for 1 min. Inlet and FID temperatures were set at 200 °C and 300 °C, respectively [ 42 ].

H 2 and CO were analyzed using a Peak Performer 1 (PP1) 910-100 trace level gas chromatography equipped with a reducing compound photometer (RCP) (method detection limit ~ 1 ppb) (Peak Laboratories, CA, USA). Column and RCP bed temperatures were set at 105 °C and 265 °C, respectively.

Acetate was analyzed using an Agilent 1260 high-performance liquid chromatography (HPLC) system (Agilent Technologies, Santa Clara, CA, USA) equipped with an Aminex HPX-87H column (Bio-Rad, Hercules, CA, USA) and a diode array detector (DAD) set at 210 nm; samples were separated at a flow rate of 0.6 mL/min using 4 mM H 2 SO 4 as the mobile phase [ 50 ].

Data availability

The BioProject accession number is PRJNA1042952. The 16S rRNA gene amplicon sequencing data are available in the Sequence Read Archive of GenBank under the accession number SRR27024736 (CO, 5th transfer, HEPES buffer), SRR27024737 (CO, 5th transfer, bicarbonate buffer), SRR27024738 (CO, 3rd transfer, bicarbonate buffer), and SRR27024739 (CO and acetate, 3rd transfer, bicarbonate buffer). The binning genomic sequence of Dehalococcoides sp. strain CO is available in GenBank under the accession number JBDODF000000000. The binning genomic sequence of Acetobacterium sp. strain Z1 is available in GenBank under the accession number JBDODG000000000. Three rdhA genes (RdhA1, RdhA2, and RdhA3) annotated from the draft Dehalococcoides sp. strain CO are available in GenBank under the accession number PP060998, PP060999, and PP061000. The partial 16S rRNA gene sequence of Dehalococcoides sp. strain CO is available under the accession number OQ946896.

CO as an electron source for reductive dechlorination of TCE

After a 3-month incubation period, the sediment microcosms supplemented with 5 mM acetate and 2 mL of CO completely dechlorinated the initial 33.9 ± 1.6 µmol of TCE to ethene. In contrast, microcosms supplemented only with 5 mM acetate and without CO were unable to achieve complete TCE dechlorination, with the process stalling at the c DCE stage with negligible amount of VC (data not shown). Over the incubation period, five doses of CO (i.e., 10 mL in total) were added into the bottles. This led to the reductive dechlorination of TCE to ethene in approximately 90 days, with c DCE and VC produced sequentially (Fig. S2A). Following four consecutive transfers, the culture maintained the ability of complete reductive dechlorination of TCE to ethene within ~ 50 days (Fig. 1 A). Specifically, TCE was dechlorinated to ethene within 30 days when H 2 was provided as the electron donor (Fig. 1 B), while TCE dechlorination stalled in approximately 100 days without H 2 or CO amendment (Fig. 1 C).

Reductive dechlorination of TCE in enrichment cultures amended with CO plus acetate. Hydrogenolysis of TCE to ethene using CO ( A ) or H 2 ( B ) as the electron donor. Stalled dechlorination of TCE in the absence of an electron donor ( C ). Error bars represent the standard deviations of triplicate samples, omitted when smaller than the symbol. The red arrows indicate CO supplementation (2 mL/dose)

Exclusive utilization of CO to support TCE reductive dechlorination

Separate microcosms were established solely with CO as the hypothesized electron and carbon source (Fig. S 1 ). After an extended incubation period of exceeding 6 months, the sediment microcosm amended with only 2 mL of CO unexpectedly achieved the dechlorination of the initial 32.5 ± 1.6 µmol of TCE to stoichiometric amounts of VC (data not shown), and the transferred cultures dechlorinated the same amount of TCE to ethene with increased dechlorination rates (Fig. S3). Subsequently, the fourth transfer, cultivated in the bicarbonate-buffered medium amended with thirteen doses of CO (i.e., 26 mL in total), demonstrated stepwise reductive dechlorination of TCE to ethene in approximately 160 days (Fig. 2 A). To further substantiate the role of CO as the sole electron and carbon source, the bicarbonate buffer system was replaced with HEPES buffer, and the headspaces were purged with pure N 2 gas. By comparison, the transferred cultures, cultivated in the HEPES-buffered medium and amended with only CO (~ 24 mL in total), also stepwise dechlorinated the same amount of TCE to 31.7 ± 0.1 µmol ethene in about 190 days, affirming that CO served not only as the electron donor but also as the carbon source (Fig. 2 B).

Reductive dechlorination of TCE to ethene by enrichment cultures only supplemented with CO in bicarbonate-buffered medium ( A ) or in HEPES-buffered medium ( B ). Error bars represent the standard deviations of triplicate samples, omitted when smaller than the symbol. The red arrows indicate the time points of CO supplementation (2 mL/dose)

Microbial community profiles of TCE-dechlorinating enrichment cultures sustained by CO

Amplicon sequencing of the 16S rRNA gene was applied to investigate the microbial population(s) responsible for CO-fueled TCE dechlorination. The enrichment cultures cultivated under different conditions exhibited varying compositions at the phylum level, with Firmicutes , Bacteroidota , Chloroflexi , Proteobacteria , Halobacterota , and Cloacimonadota being the major phyla (Fig. 3 A). Notably, the phylum Chloroflexi became dominant in enrichment cultures amended with CO as the electron donor and carbon source, regardless of the buffering agent used (bicarbonate or HEPES). At the genus level, Thermincola emerged as the predominant bacteria (53.0%) in enrichment cultures supplemented with both CO and acetate. Nonetheless, its presence was entirely absent in cultures lacking acetate amendment. This observation aligns with the known physiological capabilities of Thermincola carboxydiphila strain 2204, a described alkalitolerant, CO-utilizing, H 2 -producing, thermophilic anaerobe [ 51 ], which possesses the ability for chemolithotrophic growth via anaerobic CO oxidation coupled to H 2 and CO 2 production [ 51 , 52 ]. The second most abundant genus in CO plus acetate enrichment cultures was Sporomusa (11.9%), capable of growth on either CO or H 2 /CO 2 [ 53 ]. Methanogenic archaea Methanosarcina (2.5%) was exclusively detected in CO plus acetate enrichment cultures, with ~ 450 µmol/bottle of methane detected. In the third transferred cultures amended with CO only, the most abundant genus was Acetobacterium (64.6%), whereas its relative abundance in the third transfer cultures amended with CO plus acetate was only 1.3%. Given the capacity of several Acetobacterium species to convert CO to acetate [ 54 ], it is hypothesized that Acetobacterium in the CO-fueled enrichment cultures serves as the primary producer and provides carbon source acetate for other populations within the community. It is worth noting that the model acetogen Acetobacterium woodii cannot grow on CO as a sole carbon and energy source, suggesting that the Acetobacterium identified in this study may differ from Acetobacterium woodii [ 10 ]. Meanwhile, Acetobacterium wieringae strain JM has the ability to grow with CO as both carbon and energy source and was isolated recently [ 55 ]. Dehalococcoides (1.1–39.3%) was the only OHRB phylotype detected in all the enrichment cultures. Acetobacterium and Dehalococcoides were the top two most abundant genera in the fifth transfers cultivated with CO only (Fig. 3 B). Subsequently, we obtained a nearly complete (i.e., ~ 1300 bp) 16S rRNA gene from the CO-fed consortium using the Dehalococcoides -specific primers. As shown in Fig. 3 C, the amplicon shared 98.5–100% sequence similarities with the 16S rRNA gene of known Dehalococcoides isolates (e.g., 195, BAV1), which provides additional evidence for the presence of a Dehalococcoides population in the CO-fed TCE-dechlorinating community. We hypothesized that certain genera employ CO as a precursor to generate CO 2 and H 2 . Acetobacterium , in turn, harnesses these products to synthesize acetate. The symbiotic interaction involving H 2 and acetate facilitates the survival of Dehalococcoides and enhances its capability to reductively dechlorinate TCE to ethene within the microbial community.

Microbial community structures at both the phylum ( A ) and genus ( B ) levels in the enrichment cultures following complete TCE depletion. Maximum-likelihood phylogenetic tree of Dehalococcoides (including its three subgroups) and Dehalogenimonas based on 16S rRNA gene sequences ( C ). Bootstrap values (1000 replicates) are indicated at branch points, and the scale bar represents nucleotide substitutions per site. GenBank accession numbers are provided in parentheses

Dehalococcoides growth coupled with TCE reductive dechlorination fueled by CO

To elucidate the crucial role of CO in facilitating Dehalococcoides growth and TCE dechlorination, we conducted an experiment involving the transfer of CO enrichment cultures (in a bicarbonate buffer) with varying CO supplement doses, resulting in total added CO of 14 mL (571.4 µmol) or 35 mL (1428.6 µmol), respectively. Our findings revealed that the initial 38.1 ± 0.3 µmol TCE was dechlorinated to stoichiometric amounts of ethene within approximately 90 and 65 days in cultures supplemented with 2 mL CO/dose and 5 mL CO/dose, respectively. A clear correlation was observed between the amount and frequency of CO supplementation and the rate of TCE dechlorination (Fig. 4 A, B). Concomitant with TCE dechlorination, Dehalococcoides cell numbers in the cultures increased significantly from (3.6 ± 0.3) × 10 5 to (1.5 ± 0.2) × 10 8 cells per mL cultures (416.9-fold increase) and (1.3 ± 0.1) × 10 8 cells per mL cultures (346.4-fold increase), respectively (Fig. 4 E). Concomitant with the supplementation of CO, a noteworthy increase in H 2 production was observed. However, despite significant CO additions, H 2 generation during the TCE-to-VC dechlorination phase remained exceptionally low (maximum amounts measured were 33.7 ± 1.4 nmol/bottle and 158.1 ± 6.9 nmol/bottle for 2 and 5 mL CO doses, respectively) over approximately 40 days. Intriguingly, the accumulation of H 2 was exclusively evident during the VC-to-ethene transition, with the maximum amounts measured at 631.8 ± 172.5 nmol/bottle and 334.7 ± 158.2 nmol/bottle, respectively (Fig. 4 D). This stage-specific pattern suggests a potential shift in metabolic pathways or microbial community dynamics during the dechlorination process. Additionally, CO-fueled acetogenesis by Acetobacterium was evident in the enrichment cultures, as depicted by the final acetate concentrations of 2.4 ± 0.01 mM and 4.4 ± 0.4 mM in the 2 mL and 5 mL CO/dose cultures, respectively (Fig. 4 C). This acetate production potentially serves as a substrate for other microbial populations within the community, further influencing the observed H 2 dynamics.

Reductive dechlorination of TCE by enrichment cultures exclusively amended with 5 mL CO/dose ( A ) and 2 mL CO/dose ( B ) coupled with acetate formation ( C ), H 2 formation ( D ), and Dehalococcoides growth ( E ). Concurrently, the figures detail the growth of Dehalococcoides ( C ), the formation of H 2 ( D ), and the production of acetate ( E ). Error bars, reflecting standard deviations from triplicate samples, are omitted when their magnitude is below the symbol. The red arrows in the figures indicate the specific points of CO supplementation

Draft genome of the TCE-dechlorinating Dehalococcoides

The binning of metagenomic contigs resulted in the assembly of a draft Dehalococcoides genome, designated as strain CO. This genome comprised 4 contigs with a total size of 1,360,741 bp, a G + C content of 47.2% and N50 = 781,482 bp. CheckM analysis indicated that the genome was nearly 95.1% complete with 1.5% contamination [ 49 ]. PATRIC and RAST annotation of the draft genome predicted a total of 1497 genes including 1440 coding sequences (CDS) and 57 non-coding RNA sequences. Dehalococcoides strain CO exhibited a high genome-aggregate average nucleotide identity (ANI) with strains CBDB1 (99.3%), FL2 (99.7%), 11a5 (99.4%), and KS (99.4%) (Table S 1 ), exceeding the 95% ANI threshold for species demarcation [ 56 ]. However, strain CO showed lower ANI compared to strains 195 (86.3%), VS (86.8%), and CG3 (87.7%). A total of 20 rdhA were annotated in the draft genome of strain CO. Two identical RDases RdhA1 (NCBI Accession #PP060998) and RdhA2 (NCBI Accession #PP060999) were annotated in the draft genome of strain CO, sharing amino acid identities of 96.5%, 96.9%, 97.9%, and 96.7% with the VcrA protein sequences in the KB-1 consortium, Dehalococcoides strain VS, strain WBC-2, strain GT, respectively (Fig. S3). Another RDase RdhA3(NCBI Accession #PP061000) with a full length of 500 amino acids shared 94.4% and 99.6% amino acid identities when compared with TceA in Dehalococcoides strain 195 and the KB-1 consortium, respectively (Fig. S4). Other putative RDases exhibited relatively lower similarities to the charactered RDases.

Draft genomes of the CO-oxidating anaerobes

Binning of the metagenomic contigs enabled the assembly of a draft Acetobacterium genome, designated as strain Z1. This genome consisted of 46 contigs with a total size of 3,373,213 bp, a G + C content of 44.5%, and N50 = 781,482 bp. CheckM analysis indicated that the genome was almost 100% complete with 0.3% contamination [ 49 ]. PATRIC and RAST annotation of the draft genome predicted a total of 3298 genes, including 3255 coding sequences (CDS) and 43 non-coding RNA sequences. Strain Z1 exhibited relatively lower ANI (< 90%) and dDDH (< 70%) compared to other Acetobacterium species (Table S3). The comparison and phylogenetic tree based on the genomes (Fig. S5) indicated that strain Z1 represented a new species within the genus Acetobacterium . No RDase genes were annotated in the draft genome of strain Z1, suggesting it is not capable of organohalide respiration. The CODH annotated in the draft genome of strain Z1 shared 97.7%, 95.3%, 94.8%, 92.7%, and 90.0% amino acid identities with the CODH protein sequences in Acetobacterium woodii , Acetobacterium malicum , Acetobacterium wieringae , Acetobacterium dehalogenans , and Acetobacterium tundrae , respectively (Fig. S6). Enrichment cultures harbored a diverse microbial community, with several prominent genera— Acetobacterium , Methanosarcina , Desulfomicrobium , and Desulfocurvibacter —exhibiting the genomic potential for CO utilization via the presence of CODH. The draft genome of strain Z1 encompasses the complete WLP, with the key enzyme ACS likely playing a crucial role in survival and growth within the CO-fed cultures. H 2 formation from CO oxidation serves as a central reaction, driving electron flow throughout the community. This highlights the increasing recognition of hydrogenogenic carboxydotrophs, identified in diverse environments [ 57 ]. While H 2 production by Acetobacterium remains unreported, Acetobacterium wieringae and Acetobacterium woodii are known to generate CO 2 and acetate as CO oxidation end products [ 55 , 58 ]. The genes encoding the CO oxidation system (Coo) and energy-converting hydrogenase (Ech) serve as marker genes for hydrogenogenic carboxydotrophy [ 59 , 60 ]. Genomic annotations revealed that Desulfomicrobium , Desulfocurvibacter , Methanosarcina , Methanoculleus , Methanosarcina , and Methanofollis were annotated with both Coo and Ech, establishing them as potential H 2 producers in the CO-fed cultures.

To date, the complete detoxification of chlorinated ethenes into the environmentally benign product ethene relies exclusively on a specific subset of OHRB within the class Dehalococcoidia (e.g., Dehalococcoides , Dehalogenimonas ) [ 17 , 40 ]. It is noteworthy that all Dehalococcoides isolates exhibit a strict requirement for H 2 as electron donor, an indispensable role that cannot be substituted [ 17 ]. Various pathways for H 2 production have been demonstrated, including organic acids fermentation, phosphite oxidation, acetate oxidation, nitrogen fixation, and anaerobic carbon monoxide oxidation [ 61 ]. The established knowledge regarding the evolution of H 2 supporting OHRB has been well documented. Here, we demonstrate that CO can serve as an alternative electron donor for the dechlorination of chlorinated ethenes, ultimately yielding the environmentally friendly end product ethene.

A total of 1428.6 µmol of CO (i.e., 35 mL CO) were meticulously introduced into the 5 mL CO/dose supplemented enrichment cultures. Following the principles delineated in Table 1 , it can be deduced that each molecule of CO can be converted into one molecule of H 2 , as depicted by equation 2. Thus, the maximum theoretical H 2 production would amount to 1428.6 µmol. In accordance with equation 1, the complete dechlorination of 33.3 µmol of TCE to ethene would theoretically consume 100.0 µmoles of H 2 . The remaining H 2 , if exclusively utilized for acetate production, would reach a substantial quantity of 332.1 µmol, equivalent to 4.2 mM in an 80 mL medium, as indicated by equation 3. Remarkably, the measured final concentration of acetate was determined to be 4.4 ± 0.4 mM, underscoring the intricate metabolic dynamics orchestrated within the microbial community.

The analyses of carbon and electron balance revealed that the principal outcomes of CO oxidation in our study were the production of acetate, CO 2 , and H 2 (Table 2 ). These findings underscored the intricate interplays among CO oxidation, TCE dechlorination, and WLP in the metabolic processes occurring within the enrichment cultures. Within the enrichment cultures, a remarkable division of labor emerged concerning CO utilization. Acetobacterium assumed the primary role in converting CO into acetate, likely via the WLP. Concurrently, several hydrogenogenic carboxydotrophs (e.g., Desulfomicrobium , Desulfocurvibacter , Methanosarcina ) potentially drove the alternative pathway, transforming CO into CO 2 and H 2 . This strategic cooperation provided a dual benefit: H 2 and acetate, generated by the initial CO oxidation, were subsequently channeled to Dehalococcoides for fueling its reductive dechlorination of TCE. CO functioned as an indirect yet crucial source of both energy and carbon for Dehalococcoides , enabling its vital role in the overall dechlorination process.

Previous research had indicated the detrimental effect of CO, inhibiting the reductive dechlorination of TCE and hexachlorobenzene driven by Dehalococcoides strain 195 or CBDB1, respectively [ 27 , 63 ]. Even a modest concentration of 6 µmol per bottle for strain 195 or 1 µmol per bottle for strain CBDB1 of CO could severely impede the growth of Dehalococcoides [ 27 ]. Additionally, CO accumulation as a metabolic by-product in dechlorinating cultures dominated by Dehalogenimonas etheniformans strain GP has been shown to negatively impact reductive dechlorination activity. Externally amended CO at 4 µmol (~ 880 ppmv in the culture vessel) strongly inhibited vinyl chloride (VC) degradation by strain GP, indicating Dehalogenimonas strains, like Dehalococcoides , are sensitive to CO. These findings underscore the need for strategies (e.g., syntrophy) to mitigate CO toxicity in dechlorinating systems comprising obligate OHRB like Dehalococcoides and Dehalogenimonas [ 64 , 65 ]. Surprisingly, in our study, we amended a maximum CO (5 mL) concentration of up to 204.1 µmol per bottle. Contrary to expectations, not only did Dehalococcoides endure under such elevated CO concentrations, but it also thrived and proliferated by harnessing CO, a specific interaction mechanism hitherto undocumented in the literature. It is important to note that due to the dynamic nature of CO dissolution and consumption in the liquid phase, the actual CO concentration experienced by Dehalococcoides in our enrichment culture was likely substantially lower than the calculated equilibrium concentration. Therefore, the true CO tolerance of Dehalococcoides in our system could be lower than the levels supplemented in the culture vessels.

While CO offers advantages in terms of energy conservation compared to H 2 , its utilization by microorganisms has been restricted by issues related to microbial tolerance [ 8 ]. Nevertheless, certain anaerobes have demonstrated the capacity to utilize CO for the production of carboxylates and alcohols. Other than that, the coupling of CO oxidation with various respiratory processes, such as desulfurication, hydrogenesis, acetogenesis, and methanogenesis, has been established [ 58 ]. For instance, Clostridium ljungdahlii can produce acetate and ethanol through WLP using CO [ 66 ]. Methanogens, especially Methanosarcina acetivorans , have been extensively studied for their ability to grow on CO as the sole substrate, with the concomitant formation of acetate [ 58 , 67 ]. However, only a limited number of anaerobes capable of utilizing CO as their sole source of energy and carbon have been documented to date. Acetobacterium , a well-studied anaerobic microorganism possessing a complete WLP, is also known for its ability to utilize CO. However, the capacity to grow solely on CO as the carbon and energy source has only been observed in one strain, JM, to date [ 10 , 55 , 68 ]. In our study, we demonstrated that CO could effectively function as the sole carbon and energy source, thereby maintaining the stability of the microbial community. Acetobacterium spp. are frequently co-cultured with OHRB, playing a significant role in their activities: (1) they provide essential metabolites like acetate, vitamin B 12 , and other cofactors to support the growth and dehalogenation capabilities of OHRB such as Dehalococcoides , Trichlorobacter (formerly Geobacter ), and Sulfurospirillum ; (2) they can mitigate the toxicity of CO, a common inhibitor of OHRB; and (3) certain strains, like Acetobacterium strain AG, possess the ability to directly debrominate polybrominated diphenyl ethers (PBDEs), suggesting facultative organohalide respiration within the genus [ 35 , 36 , 37 , 38 , 69 , 70 , 71 , 72 ]. Additionally, our findings regarding CO-dependent H 2 production hold significant implications, offering a promising alternative in the context of diminishing fossil fuel resources [ 58 ]. It is crucial to acknowledge that H 2 production coupled with CO oxidation has been infrequently observed, possibly due to technological limitations. The exploration of CO-dependent energy conservation presents an exciting avenue for future research.

H 2 is produced in anoxic environments through the oxidation of organic matter [ 73 , 74 ]. In addition to anaerobic fermentation, H 2 can also be generated directly or indirectly through bio-photolysis, photo-fermentation, CO gas-fermentation, and nitrogen fixation [ 61 , 75 , 76 ]. For instance, nitrogen fixation, despite its energy consumption, results in the annual production of 2.4–4.9 Tg H 2 per year [ 75 ]. These H 2 can be rapidly consumed in microbial-mediated terminal electron-accepting processes, such as iron reduction, sulfate reduction, denitrification, methanogenesis, and organohalide respiration [ 73 , 74 ]. By comparison, the organohalide respiration process can compete with other electron-accepting processes, possessing a thermodynamic advantage. This advantage arises from the ability of organohalide-respiring bacteria to utilize a relatively low threshold H 2 concentration [ 77 ]. The H 2 threshold concentrations for the reduction of various chlorinated compounds differ. For instance, the mean H 2 concentrations during the reductive dehalogenation of 2,4-dichlorophenol (2,4-CP), 2,3,4-trichlorophenol (2,3,4-CP), pentachlorophenol (PCP), and tetrachloroethene (PCE) were 3.6 nM, 4.1 nM, 0.3 nM, and 0.8 nM, respectively [ 77 ]. H 2 threshold concentrations range from 0.6 to 0.9 nM for PCE and TCE reduction, 0.1–2.5 nM for c DCE reduction, and 2–24 nM for VC reduction [ 78 , 79 ]. In our study, a noticeable production of H 2 from CO oxidation was observed only between approximately day 60 and day 75. We speculate that during the reductive dechlorination process from TCE to VC, H 2 produced from CO oxidation was promptly utilized for dechlorination. Low concentrations of H 2 may have failed to fuel VC dechlorination, resulting in H 2 accumulation (Fig. 4 D). These findings align with previous reports indicating that electron donor (e.g., H 2 ) limitation can inhibit the growth of VC-dechlorinating Dehalococcoides populations [ 80 ]. The dynamic interplay between hydrogenogenic carboxydotrophy and Dehalococcoides , involving H 2 transfer, indicates a microbial ecological collaboration with advantages. Further investigation is warranted to confirm the underlying mechanisms governing this intricate microbial interaction.

In this study, in addition to Dehalococcoides and Acetobacterium , draft genomes for several other genera, including Youngiibacter , Desulfocurvibacter , Gudongella , Methanofollis , Aminivibrio , and Petrimonas (Table S4), were successfully assembled. Youngiibacter , a strictly anaerobic microorganism, ferments various carbohydrates into ethanol, formate, acetate, and CO 2 [ 81 ]. It likely engages in the fermentation of unidentified carbohydrates in CO-supplemented enrichment cultures. Desulfocurvibacter , a sulfate-reducing bacterium, typically thrives through pyruvate fermentation [ 82 ]; by comparison, it may function as a CO consumer in this study. Gudongella strain W6 T exhibits N 2 -fixing capability and utilizes amino acids while refraining from growth on acetate [ 83 ]. Methanofollis , a strictly anaerobic archaeon, oxidizes CO to produce H 2 and CO 2 , and employs H 2 and acetate to produce methane in CO-fed cultures [ 84 ]. Aminivibrio and Petrimonas are anaerobic fermentative bacteria with the capacity to ferment organic acids [ 85 , 86 ]. Nevertheless, elucidating the precise functions of these anaerobes within CO-oxidizing and dechlorinating microbial communities remains challenging and speculative at this juncture (Fig. 5 ). Top-down approaches, involving the reduction of microbial community complexity through serial dilution or the isolation of specific microorganisms, and bottom-up strategies, integrating and synthesizing co-cultures or tri-cultures, hold promise for providing insights into the potential ecological functions of these anaerobes.

Carbon recovery and electron recovery, acetate, ethene, and methane were the main three products ( A ). Proposed interaction networks within CO-fed TCE-dechlorinating cultures based on assembled draft genomes of various genera suggest diverse metabolic pathways. CO oxidation to CO 2 and H 2 is hypothesized to occur in Desulfocurvibacter , Desulfomicrobium , and Methanosarcina , facilitated by the presence of CODH and Ech. Acetobacterium is identified as capable of exclusively oxidizing CO to acetate, attributed to the presence of complete WLP genes. Acetate and H 2 collectively support the reductive dechlorination of TCE to ethene by Dehalococcoides . Methanosarcina and Methanofollis utilize acetate, H 2 , and CO 2 to produce methane. Genera such as Youngiibacter , Gudongella , and Petrimonas , identified as fermentation specialists, demonstrate the ability to metabolize carbohydrates and some organic acids, while Aminivibrio , a fermentation bacterium, exhibits a preference for acetate utilization. These proposed interactions outline a complex web of metabolic relationships in the CO-enriched TCE-dechlorinating cultures ( B )

In summary, the biologically mediated “water-gas shift reaction” (CO + H 2 O ⇌ CO 2 + H 2 ) is predominantly catalyzed by CODH in potential hydrogenogenic carboxydotrophy Desulfomicrobium , Desulfocurvibacter , Methanosarcina , Methanoculleus , Methanosarcina , and Methanofollis . This enzymatic process results in the formation of H 2 and CO 2 , which are subsequently utilized by Acetobacterium and Methanosarcina in acetogenesis and methanogenesis, respectively. The produced acetate and H 2 are accessible for Dehalococcoides , enabling the reductive dechlorination of TCE to ethene. Additionally, acetate serves as a versatile carbon source, potentially harnessed by Aminivibrio , Petrimonas , Methanofollis , Methanosarcina , and other microbial groups. H 2 , acting as a ubiquitous energy currency in anoxic environments, underscores its essential role in interspecies H 2 transfer (IHT), crucial for maintaining the community structure and function of CO-fed enrichment cultures (Fig. 5 ).

Availability of data and materials

All sequencing data generated and analyzed in this study have been deposited in the NCBI Sequence Read Archive (SRA) under the accession numbers provided in the Data availability section. Additional data or materials relevant to the study are available from the corresponding author upon reasonable request.

Olson KR, Donald JA, Dombkowski RA, Perry SF. Evolutionary and comparative aspects of nitric oxide, carbon monoxide and hydrogen sulfide. Respir Physiol Neurobiol. 2012;184(2):117–29.

Article PubMed CAS Google Scholar

Kharecha P, Kasting J, Siefert J. A coupled atmosphere–ecosystem model of the early Archean Earth. Geobiology. 2005;3(2):53–76.

Article CAS Google Scholar

Martin W, Baross J, Kelley D, Russell MJ. Hydrothermal vents and the origin of life. Nat Rev Microbiol. 2008;6(11):805–14.

Huber C, Wächtershäuser G. Activated acetic acid by carbon fixation on (Fe, Ni)s under primordial condition s . Science. 1997;276(5310):245–7.

Ducat DC, Silver PA. Improving carbon fixation pathways. Curr Opin Chem Biol. 2012;16(3):337–44.

Article PubMed PubMed Central CAS Google Scholar

Gong F, Cai Z, Li Y. Synthetic biology for CO 2 fixation. Sci China Life Sci. 2016;59(11):1106–14.

Ragsdale SW. Life with carbon monoxide. Crit Rev Biochem. 2004;39(3):165–95.

Diender M, Stams AJM, Sousa DZ. Pathways and bioenergetics of anaerobic carbon monoxide fermentation. Front Microbiol. 2015;6:1275.

Article PubMed PubMed Central Google Scholar

Cordero PRF, Bayly K, Leung PM, Huang C, Islam ZF, Schittenhelm RB, et al. Carbon monoxide dehydrogenases enhance bacterial survival by respiring atmospheric CO . bioRxiv. 2019:628081. https://doi.org/10.1101/628081 .

Bertsch J, Müller V, Lovell CR. CO metabolism in the acetogen Acetobacterium woodii . Appl Environ Microbiol. 2015;81(17):5949–56.

Uffen RL. Anaerobic growth of a Rhodopseudomonas species in the dark with carbon monoxide as sole carbon and energy substrate. PNAS. 1976;73(9):3298–302.

DePoy AN, King GM, Ohta H. Anaerobic carbon monoxide uptake by microbial communities in volcanic deposits at different stages of successional development on O-yama volcano, Miyake-jima, Japan. Microorganisms. 2020;9(1):12.

Hug LA, Maphosa F, Leys D, Löffler FE, Smidt H, Edwards EA, et al. Overview of organohalide-respiring bacteria and a proposal for a classification system for reductive dehalogenases. Philos Trans R Soc Lond B Biol Sci. 2013;368(1616):20120322.

Yohda M, Ikegami K, Aita Y, Kitajima M, Takechi A, Iwamoto M, et al. Isolation and genomic characterization of a Dehalococcoides strain suggests genomic rearrangement during culture. Sci Rep. 2017;7(1):2230.

Asai M, Morita Y, Meng L, Miyazaki H, Yoshida N. Dehalococcoides mccartyi strain NIT01 grows more stably in vessels made of pure titanium rather than the stainless alloy SUS304. Environ Microbiol Rep. 2023;15(6):557–67.

Saiyari DM, Chuang H, Senoro DB, Lin T, Whang L, Chiu Y, et al. A review in the current developments of genus Dehalococcoides , its consortia and kinetics for bioremediation options of contaminated groundwater. Sustain Environ Res. 2018;28(4):149–57.

Löffler FE, Yan J, Ritalahti KM, Adrian L, Edwards EA, Konstantinidis KT, et al. Dehalococcoides mccartyi gen. nov., sp. nov., obligately organohalide-respiring anaerobic bacteria relevant to halogen cycling and bioremediation, belong to a novel bacterial class, D ehalococcoidia classis nov., order D ehalococcoidales ord. nov. and family D ehalococcoidaceae fam. nov., within the phylum C hloroflexi . Int J Syst Evol Microbiol. 2015;65(6):2015–15.

Article PubMed Google Scholar

Maymó-Gatell X, Anguish T, Zinder SH. Reductive dechlorination of chlorinated ethenes and 1,2-dichloroethane by “ Dehalococcoides ethenogenes ” 195. Appl Environ Microbiol. 1999;65(7):3108–13.

Magnuson Jon K, Romine Margaret F, Burris David R, Kingsley MT. Trichloroethene reductive dehalogenase from Dehalococcoides ethenogenes : sequence of tceA and substrate range characterization. Appl Environ Microbiol. 2000;66(12):5141–7.

Article PubMed Central Google Scholar

He J, Ritalahti KM, Yang K, Koenlgsberg SS, Löffler FE. Detoxification of vinyl chloride to ethene coupled to growth of an anaerobic bacterium. Nature. 2003;424(6944):62–5.

Krajmalnik-Brown R, Hölscher T, Thomson IN, Saunders FM, Ritalahti KM, Löffler FE. Genetic identification of a putative vinyl chloride reductase in Dehalococcoides sp. strain BAV1. Appl Environ Microbiol. 2004;70(10):6347–51.

Lee PKH, Cheng D, West KA, Alvarez-Cohen L, He J. Isolation of two new Dehalococcoides mccartyi strains with dissimilar dechlorination functions and their characterization by comparative genomics via microarray analysis. Environ Microbiol. 2013;15(8):2293–305.

Parthasarathy A, Stich TA, Lohner ST, Lesnefsky A, Britt RD, Spormann AM. Biochemical and EPR-spectroscopic investigation into heterologously expressed vinyl chloride reductive dehalogenase (VcrA) from Dehalococcoides mccartyi strain VS. J Am Chem Soc. 2015;137(10):3525–32.

Müller Jochen A, Rosner Bettina M, von Abendroth G, Meshulam-Simon G, McCarty Perry L, Spormann Alfred M. Molecular identification of the catabolic vinyl chloride reductase from Dehalococcoides sp. strain VS and its environmental distribution. Appl Environ Microbiol. 2004;70(8):4880–8.

Kube M, Beck A, Zinder SH, Kuhl H, Reinhardt R, Adrian L. Genome sequence of the chlorinated compound–respiring bacterium Dehalococcoides species strain CBDB1. Nat Biotechnol. 2005;23(10):1269–73.

Seshadri R, Adrian L, Fouts DE, Eisen JA, Phillippy AM, Methe BA, et al. Genome sequence of the PCE-dechlorinating bacterium Dehalococcoides ethenogenes . Science. 2005;307(5706):105–8.

Zhuang W-Q, Yi S, Bill M, Brisson VL, Feng X, Men Y, et al. Incomplete Wood-Ljungdahl pathway facilitates one-carbon metabolism in organohalide-respiring Dehalococcoides mccartyi . PNAS. 2014;111(17):6419–24.

Chin BY, Otterbein LE. Carbon monoxide is a poison … to microbes! CO as a bactericidal molecule. Curr Opin Pharmacol. 2009;9(4):490–500.

Fukuyama Y, Inoue M, Omae K, Yoshida T, Sako Y. Chapter three - Anaerobic and hydrogenogenic carbon monoxide-oxidizing prokaryotes: versatile microbial conversion of a toxic gas into an available energy. In: Gadd GM, Sariaslani S, editors. Advances in applied microbiology, Volume 110. New York: Academic Press; 2020. p. 99–148.

Google Scholar

Chen C, Xu G, He J. Substrate-dependent strategies to mitigate sulfate inhibition on microbial reductive dechlorination of polychlorinated biphenyls. Chemosphere. 2023;342:140063.

Ferry JG, House CH. The stepwise evolution of early life driven by energy conservation. Mol Biol Evol. 2006;23(6):1286–92.

Smidt H, de Vos WM. Anaerobic microbial dehalogenation. Annu Rev Microbiol. 2004;58:43–73.

Meßmer M, Wohlfarth G, Diekert G. Methyl chloride metabolism of the strictly anaerobic, methyl chloride-utilizing homoacetogen strain MC. Arch Microbiol. 1993;160(5):383–7.

Article Google Scholar

Traunecker J, Preuß A, Diekert G. Isolation and characterization of a methyl chloride utilizing, strictly anaerobic bacterium. Arch Microbiol. 1991;156(5):416–21.

Ziv-El M, Popat SC, Parameswaran P, Kang D-W, Polasko A, Halden RU, et al. Using electron balances and molecular techniques to assess trichoroethene-induced shifts to a dechlorinating microbial community. Biotechnol Bioeng. 2012;109(9):2230–9.

Trueba-Santiso A, Fernandez-Verdejo D, Marco-Rius I, Soder-Walz JM, Casabella O, Vicent T, et al. Interspecies interaction and effect of co-contaminants in an anaerobic dichloromethane-degrading culture. Chemosphere. 2020;240:124877.

Ding C, Chow Wai L, He J. Isolation of Acetobacterium sp. strain AG, which reductively debrominates octa- and pentabrominated diphenyl ether technical mixtures. Appl Environ Microbiol. 2013;79(4):1110–7.

Lim ML, Brooks MD, Boothe MA, Krzmarzick MJ. Novel bacterial diversity is enriched with chloroperoxidase-reacted organic matter under anaerobic conditions. FEMS Microbiol Ecol. 2018;94(5):fiy050.

Yang Y, Capiro NL, Marcet TF, Yan J, Pennell KD, Löffler FE. Organohalide respiration with chlorinated ethenes under low pH conditions. Environ Sci Technol. 2017;51(15):8579–88.

Yang Y, Higgins SA, Yan J, Simsir B, Chourey K, Iyer R, et al. Grape pomace compost harbors organohalide-respiring Dehalogenimonas species with novel reductive dehalogenase genes. ISME J. 2017;11(12):2767–80.

Löffler FE, Sanford RA, Ritalahti KM. Enrichment, cultivation, and detection of reductively dechlorinating bacteria. In: Methods in enzymology, volume 397. New York: Academic Press; 2005. p. 77–111.

Jiang L, Yang Y, Jin H, Wang H, Swift CM, Xie Y, et al. Geobacter sp. strain IAE dihaloeliminates 1,1,2-trichloroethane and 1,2-dichloroethane. Environ Sci Technol. 2022;56(6):3430–40.

Yang Y, Sanford R, Yan J, Chen G, Capiro NL, Li X, et al. Roles of organohalide-respiring D ehalococcoidia in carbon cycling. mSystems. 2020;5(3):e00757-19.

Wolin EA, Wolin MJ, Wolfe RS. Formation of methane by bacterial extracts. J Biol Chem. 1963;238(8):2882–6.

Kalendar R, Boronnikova S, Seppänen M. Isolation and purification of DNA from complicated biological samples. In: Besse P, editor. Molecular plant taxonomy: methods and protocols. New York: Springer, US; 2021. p. 57–67.

Chapter Google Scholar

Arkin AP, Cottingham RW, Henry CS, Harris NL, Stevens RL, Maslov S, et al. KBase: the United States department of energy systems biology knowledgebase. Nat Biotechnol. 2018;36(7):566–9.

Menzel P, Ng KL, Krogh A. Fast and sensitive taxonomic classification for metagenomics with Kaiju. Nat Commun. 2016;7:11257.

Wu YW, Simmons BA, Singer SW. Maxbin 2.0: an automated binning algorithm to recover genomes from multiple metagenomic datasets. Bioinformatics. 2016;32(4):605–7.

Parks DH, Imelfort M, Skennerton CT, Hugenholtz P, Tyson GW. CheckM: assessing the quality of microbial genomes recovered from isolates, single cells, and metagenomes. Genome Res. 2015;25(7):1043–55.

Yan J, Im J, Yang Y, Löffler FE. Guided cobalamin biosynthesis supports Dehalococcoides mccartyi reductive dechlorination activity. Philos Trans R Soc Lond B Biol Sci. 2013;368(1616):20120320.

Sokolova TG, Kostrikina NA, Chernyh NA, Kolganova TV, Tourova TP, Bonch-Osmolovskaya EA. Thermincola carboxydiphila gen. nov., sp. nov., a novel anaerobic, carboxydotrophic, hydrogenogenic bacterium from a hot spring of the Lake Baikal area. Int J Syst Evol Microbiol. 2005;55(Pt 5):2069–73.

Zavarzina DG, Sokolova TG, Tourova TP, Chernyh NA, Kostrikina NA, Bonch-Osmolovskaya EA. Thermincola ferriacetica sp. nov., a new anaerobic, thermophilic, facultatively chemolithoautotrophic bacterium capable of dissimilatory Fe(III) reduction. Extremophiles. 2007;11(1):1–7.

Breznak JA. The genus Sporomusa . In: Dworkin M, Falkow S, Rosenberg E, Schleifer K-H, Stackebrandt E, editors. The prokaryotes: volume 4: Bacteria: Firmicutes , Cyanobacteria . New York: Springer, US; 2006. p. 991–1001.

Najafpour GD. Chapter 3 - Gas and liquid system (aeration and agitation). In: Najafpour GD, editor. Biochemical engineering and biotechnology. Amsterdam: Elsevier; 2007. p. 22–68.

Arantes AL, Moreira JPC, Diender M, Parshina SN, Stams AJM, Alves MM, et al. Enrichment of anaerobic syngas-converting communities and isolation of a novel carboxydotrophic A cetobacterium wieringae strain JM. Front Microbiol. 2020;11:58.

Goris J, Konstantinidis KT, Klappenbach JA, Coenye T, Vandamme P, Tiedje JM. DNA–DNA hybridization values and their relationship to whole-genome sequence similarities. Int J Syst Evol Microbiol. 2007;57(1):81–91.

Robb F, Techtmann S. Life on the fringe: microbial adaptation to growth on carbon monoxide [version 1; peer review: 3 approved]. F1000Res. 2018;7:1981.

Oelgeschläger E, Rother M. Carbon monoxide-dependent energy metabolism in anaerobic bacteria and archaea. Arch Microbiol. 2008;190(3):257–69.

Esquivel-Elizondo S, Maldonado J, Krajmalnik-Brown R. Anaerobic carbon monoxide metabolism by Pleomorphomonas carboxyditropha sp nov, a new mesophilic hydrogenogenic carboxydotroph. FEMS Microbiol Ecol. 2018;94(6). https://doi.org/10.1093/femsec/fiy056 .

Esquivel-Elizondo S, Delgado AG, Krajmalnik-Brown R. Evolution of microbial communities growing with carbon monoxide, hydrogen, and carbon dioxide. FEMS Microbiol Ecol. 2017;93(6). https://doi.org/10.1093/femsec/fix076 .

Akhlaghi N, Najafpour-Darzi G. A comprehensive review on biological hydrogen production. Int J Hydrogen Energ. 2020;45(43):22492–512.

Lide DR. Handbook of chemistry and physics. 84th ed. Boca Raton: LLC: CRC Press; 2004. p. 2616.

Chau ATT, Lee M, Adrian L, Manefield MJ. Syntrophic partners enhance growth and respiratory dehalogenation of hexachlorobenzene by D ehalococcoides mccartyi strain CBDB1. Front Microbiol. 2018;9:1927.

Chen G, Kara Murdoch F, Xie Y, Murdoch Robert W, Cui Y, Yang Y, et al. Dehalogenation of chlorinated ethenes to ethene by a novel isolate, “ Candidatus Dehalogenimonas etheniformans”. Appl Environ Microbiol. 2022;88(12):e00443-e522.

Cui Y, Li X, Yan J, Lv Y, Jin H, Wang J, et al . Dehalogenimonas etheniformans sp. nov., a formate-oxidizing, organohalide-respiring bacterium isolated from grape pomace . Int J Syst Evol Micr. 2023;73(5). https://doi.org/10.1099/ijsem.0.005881 .

Köpke M, Held C, Hujer S, Liesegang H, Wiezer A, Wollherr A, et al. Clostridium ljungdahlii represents a microbial production platform based on syngas. PNAS. 2010;107(29):13087–92.

Diender M, Pereira R, Wessels HJ, Stams AJ, Sousa DZ. Proteomic analysis of the hydrogen and carbon monoxide metabolism of Methanothermobacter marburgensis . Front Microbiol. 2016;7:1049.

Ragsdale SW, Pierce E. Acetogenesis and the Wood-Ljungdahl pathway of CO 2 fixation. Biochim Biophys Acta Gen Subj. 2008;1784(12):1873–98.

Qiao W, Liu G, Li M, Su X, Lu L, Ye S, et al. Complete reductive dechlorination of 4-hydroxy-chlorothalonil by Dehalogenimonas populations. Environ Sci Technol. 2022;56(17):12237–46.

Duhamel M, Wehr SD, Yu L, Rizvi H, Seepersad D, Dworatzek S, et al. Comparison of anaerobic dechlorinating enrichment cultures maintained on tetrachloroethene, trichloroethene, cis -dichloroethene and vinyl chloride. Water Res. 2002;36(17):4193–202.

Duhamel M, Edwards EA. Microbial composition of chlorinated ethene-degrading cultures dominated by Dehalococcoides . FEMS Microbiol Ecol. 2006;58(3):538–49.

Zhao S, Ding C, Xu G, Rogers MJ, Ramaswamy R, He J. Diversity of organohalide respiring bacteria and reductive dehalogenases that detoxify polybrominated diphenyl ethers in E-waste recycling sites. ISME J. 2022;16(9):2123–31.

Shin H-S, Youn J-H, Kim S-H. Hydrogen production from food waste in anaerobic mesophilic and thermophilic acidogenesis. Int J Hydrogen Energ. 2004;29(13):1355–63.

Hoehler TM, Alperin MJ, Albert DB, Martens CS. Thermodynamic control on hydrogen concentrations in anoxic sediments. Geochim Cosmochim Acta. 1998;62(10):1745–56.

Conrad R, Seiler W. Contribution of hydrogen production by biological nitrogen fixation to the global hydrogen budget. J Geophys Res Oceans. 1980;85(C10):5493–8.

Bellenger JP, Darnajoux R, Zhang X, Kraepiel AML. Biological nitrogen fixation by alternative nitrogenases in terrestrial ecosystems: a review. Biogeochemistry. 2020;149(1):53–73.

Mazur CS, Jones WJ, Tebes-Stevens C. H 2 consumption during the microbial reductive dehalogenation of chlorinated phenols and tetrachloroethene. Biodegradation. 2003;14(4):285–95.

Luijten ML, Roelofsen W, Langenhoff AA, Schraa G, Stams AJ. Hydrogen threshold concentrations in pure cultures of halorespiring bacteria and at a site polluted with chlorinated ethenes. Environ Microbiol. 2004;6(6):646–50.

Lu XX, Tao S, Bosma T, Gerritse J. Characteristic hydrogen concentrations for various redox processes in batch study. J Environ Sci Health A Tox Hazard Subst Environ Eng. 2001;36(9):1725–34.

Mayer-Blackwell K, Azizian MF, Green JK, Spormann AM, Semprini L. Survival of vinyl chloride respiring Dehalococcoides mccartyi under long-term electron donor limitation. Environ Sci Technol. 2017;51(3):1635–42.

Wawrik CB, Callaghan AV, Stamps BW, Wawrik B. Genome sequence of Y oungiibacter fragilis , the type strain of the genus Y oungiibacter . Genome Announc. 2014;2(1):e01183-13. https://doi.org/10.1128/genomea.01183-13 .

Galushko A, Kuever J. Desulfocurvibacter. In; Bergey’s manual of systematics of archaea and bacteria. 2020. p. 1–6.

Wu K, Dai L, Tu B, Zhang X, Zhang H, Deng Y, et al. Gudongella oleilytica gen. nov., sp. nov., an aerotorelant bacterium isolated from Shengli oilfield and validation of family Tissierellaceae . Int J Syst Evol Microbiol. 2020;70(2):951–7.

Imachi H, Sakai S, Nagai H, Yamaguchi T, Takai K. Methanofollis ethanolicus sp. nov., an ethanol-utilizing methanogen isolated from a lotus field. Int J Syst Evol Microbiol. 2009;59(4):800–5.

Honda T, Fujita T, Tonouchi A. Aminivibrio pyruvatiphilus gen. nov., sp. nov., an anaerobic, amino-acid-degrading bacterium from soil of a Japanese rice field. Int J Syst Evol Microbiol. 2013;63(Pt_10):3679–86.

Grabowski A, Tindall BJ, Bardin V, Blanchet D, Jeanthon C. Petrimonas sulfuriphila gen. nov., sp. nov., a mesophilic fermentative bacterium isolated from a biodegraded oil reservoir. Int J Syst Evol Microbiol. 2005;55(3):1113–21.

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This work was supported by the National Key Research and Development Program of China (Grant No. 2023YFE0122000), National Natural Science Foundation of China (Grant No. 42177220 and 42377133), Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. ZDBS-LY-DQC038), Natural Science Foundation of Liaoning Province of China (Grant No. 2021-MS-026), Zhiyuan Science Foundation of BIPT (Grant No.2023004), and Major Program of Institute of Applied Ecology, Chinese Academy of Sciences (Grant No. IAEMP202201).

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JJW designed and conducted the experiments, analyzed and interpreted the data, and wrote the initial draft and revisions of the manuscript. XYL conducted experiments, analyzed and interpreted data, acquired funding, and contributed to manuscript revisions. HJJ analyzed and interpreted data and contributed to manuscript revisions. SJY, LY, HYW, SQH, HYL, and XHW conducted experiments and contributed to data analysis and interpretation. JY provided resources and supervised experiments, data analysis, and interpretation, as well as reviewed and edited the manuscript. YY provided resources, oversaw experiments, acquired funding, analyzed and interpreted data, and revised and edited the manuscript. All authors have read and approved the final manuscript.

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Additional file 1: Figure S1. Microcosm setup and transferred enrichment cultures. Trichloroethylene (TCE) was dechlorinated in enrichment cultures fed with acetate and CO (represented by the royal blue bottles). Similarly, TCE dechlorination occurred in CO-fed enrichment cultures with bicarbonate-buffered medium (represented by the green bottles) and HEPES-buffered medium (represented by the orange bottles). Conversely, in acetate-fed enrichment cultures without CO or H 2 supplementation (represented by the yellow bottles), the TCE dechlorination process did not occur, denoted by the symbol “X”, signifying the inability to dechlorinate. Figure S2. Reductive dechlorination of TCE in CO plus acetate enrichment cultures from transfer 1 to transfer 3. Approximately 33 μmol of TCE was dechlorinated to ethene over 100 days in transfer 1 cultures fed with acetate and CO (A). In transfer 2 cultures, 33 μmol of TCE was dechlorinated to ethene within 30 days, and an additional 33 μmol of TCE was dechlorinated within 25 days (B). In transfer 3 cultures, 33 μmol of TCE was dechlorinated to ethene over 50 days (C). Red arrows indicate CO additions, with each dose amounting to 2 mL. Figure S3. Reductive dechlorination of TCE in CO-fed enrichment cultures from transfer 2 to transfer 4. Approximately 33 μmol of TCE was dechlorinated to VC over 120 days in transfer 2 cultures (A). In transfer 3 cultures, 33 μmol of TCE was dechlorinated to VC with a small amount of ethene in 80 days (B). In transfer 4 cultures, 33 μmol of TCE was dechlorinated to ethene over 160 days (C). Red arrows indicate CO additions, with each dose amounting to 2 mL. Figure S4. Phylogenetic tree constructed based on the amino acid sequences of 43 RDases, with branches calculated from 500 bootstrap iterations. Functional assignments of these RDases were determined through biochemical characterization, expression analysis, or phylogenetic inference, representing a diverse array of OHRB. The tree also includes 20 RDases annotated from the draft genome of strain CO, highlighted in blue branches. Figure S5. Phylogeny of Acetobacterium based on genome sequences. The tree was constructed using the maximum-likelihood method, with GenBank accession numbers provided in parentheses. Bootstrap values, derived from 1,000 resamplings, are indicated at branching points. Figure S6. Phylogenetic tree based on protein sequences of 63 carbon monoxide dehydrogenases (CODHs) from diverse bacteria and methanogens (archaea). CODHs from methanogens are indicated with a blue background, those from Acetobacterium with a green background, and CODHs identified in CO enrichment cultures are highlighted in blue. Figure S7. Proposed model for interspecies interactions supporting TCE-to-ethene dechlorination by Dehalococcoides with CO as electron donor and carbon source. Hydrogenogenic carboxydotrophs (e.g., Methanosarcina ) oxidize CO, generating H 2 . This H 2 is then transferred to Acetobacterium , which in turn produces acetate. Both acetate and H 2 are subsequently utilized by Dehalococcoides for reductive dechlorination of TCE to ethene. Additionally, Methanosarcina can use acetate and H 2 to produce methane. Table S1. The average nucleotide identity (%) and digital DNA-DNA hybridization (%) of strain CO with other strains in the genus of Dehalococcoides . Table S2. RDases with assigned functions and their host OHRB used in Figure S4. Table S3. The average nucleotide identity (%) and digital DNA-DNA hybridization (%) of strain Z1 with other strains in the genus of Acetobacterium . Table S4 Metagenome-assembled genomes recovered from CO-fed TCE-dechlorinating enrichment cultures.

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Wang, J., Li, X., Jin, H. et al. CO-driven electron and carbon flux fuels synergistic microbial reductive dechlorination. Microbiome 12 , 154 (2024). https://doi.org/10.1186/s40168-024-01869-y

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In 1896, Thomson wondered if there might have been something wrong with Hertz's experiment with the two plates. Thomson knew that the cathode ray tubes that they had only work if there is a little air in the tube and the amount of air needed depended on the shape of the terminals. Thomson wondered if the air affected the results.
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To see all my Chemistry videos, check outhttp://socratic.org/chemistryJ.J. Thompson discovered the electron, the first of the subatomic particles, using the ...
Cathode Ray Experiment by J. J. Thomson
Thomson's First Cathode Ray Experiment. Thomson had an inkling that the 'rays' emitted from the electron gun were inseparable from the latent charge, and decided to try and prove this by using a magnetic field. His first experiment was to build a cathode ray tube with a metal cylinder on the end. This cylinder had two slits in it, leading ...
Three Experiments and One Big Idea
Three experiments led him to this.: irst, in a variation of an 1895 experiment by Jean Perrin, Thomson built a cathode ray tube ending in a pair of metal cylinders with a slit in them. These cylinders were in turn connected to an electrometer, a device for catching and measuring electrical charge. Perrin had found that cathode rays deposited an ...
J.J. Thomson
Joseph John Thomson, who was always called J.J., was born in Cheetham Hill, England, near Manchester, in 1856. His father was a bookseller who planned for Thomson to be an engineer. When an ...
JJ Thomson Cathode Ray Tube Experiment: the Discovery of the Electron
In 1897, JJ Thomson discovered the electron in his famous cathode ray tube experiment. How did it work and why did Thomson do the experiment in the first pl...
JJ Thomson and the discovery of the electron
In this video I review, with the physics explained, how JJ Thomson discovered the electronI briefly review the history prior and also discuss electric fields...
British physicist J.J. Thomson announces the discovery of ...
On April 30, 1897, British physicist J.J. Thomson announced his discovery that atoms were made up of smaller components. This finding revolutionized the way scientists thought about the atom and ...
Khan Academy
Khan Academy
Thomson's Discovery of The Electron
As a result, Thomson's experiment led to the discovery of the first subatomic particle - the electron. The charge to mass ratio of electrons was shown to be 1800 times greater than that of hydrogen ions. Thomson assumed the magnitude of charge is equal for these particles, leading to the conclusion that the mass of an electron is 1800 times ...
J. J. Thomson 1897
J. J. Thomson (1856-1940) Cathode Rays Philosophical Magazine, 44, 293-316 (1897).. The experiments* discussed in this paper were undertaken in the hope of gaining some information as to the nature of the Cathode Rays. The most diverse opinions are held as to these rays; according to the almost unanimous opinion of German physicists they are due to some process in the aether to which--inasmuch ...
J.J. Thomson's Cathode Ray Tube Experiment
Additionally, J.J. Thomson's cathode ray tube experiment is what allowed for the discovery of the first subatomic particle, the electron. Computer monitors and televisions are composed of cathode ...
The world's fastest microscope captures electrons down to the
The 'attomicroscope' consists of two sections. The top converts is an ultraviolet pulse that release ultra fast electrons inside the microscope, while the bottom section uses another two lasers to ...
Freeze-frame: Researchers develop world's fastest microscope that can
A transmission electron microscope is a tool used by scientists and researchers to magnify objects up to millions of times their actual size in order to see details too small for a traditional ...
CO-driven electron and carbon flux fuels synergistic microbial
Background Carbon monoxide (CO), hypothetically linked to prebiotic biosynthesis and possibly the origin of the life, emerges as a substantive growth substrate for numerous microorganisms. In anoxic environments, the coupling of CO oxidation with hydrogen (H2) production is an essential source of electrons, which can subsequently be utilized by hydrogenotrophic bacteria (e.g., organohalide ...

Cathode Ray Experiment

Table of Contents

Apparatus Setup

J. J. Thomson Experiment – The Discovery of Electron

Uses of Cathode Ray Tube

Frequently Asked Questions – FAQs

Where can you find a cathode ray tube?

How did JJ Thomson find the electron?

What are the properties of cathode rays?

What do you mean by cathode?

Who discovered the cathode rays?

Which gas is used in the cathode ray experiment?

What is the Colour of the cathode ray?

How cathode rays are formed?

What are cathode rays made of?

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Discovering the electron: JJ Thomson and the Cathode Ray Tube

Concept Introduction: JJ Thomson and the Discovery of the Electron

Further Reading on the Electron

Who was JJ Thomson?

What is a cathode ray tube and why was it important?

How did Thomson make these discoveries?

Why was the discovery of the electron important?

Interesting Facts about JJ Thomson

Discovery of the Electron: Further Reading

Subatomic science: JJ Thomson's discovery of the electron

What is an electron?

John Dalton's atomic theory

JJ Thomson's cathode ray tube experiments

G Johnstone Stoney coins the term 'electron'

JJ Thomson and the Royal Institution

JJ Thomson's Nobel Prize

More about the history of the Ri

Art, culture and society History of science

History of science

Who discovered the greenhouse effect?

J. J. Thomson and the Existence of the Electron

Background J. J. Thomson

The Discovery of the Electron

Discovering Evidence for Isotopes

Tabea Tietz

Further Projects

Legal Notice

Supplement to Experiment in Physics

Support SEP

Enhanced Page Navigation

George Paget Thomson

Electronic Waves

Nobel Prizes and laureates

Explore prizes and laureates

Joseph John “J. J.” Thomson

Structure of the Atom and Mass Spectrography

Early Life and Education

Ties to the Chemical Community

A Nobel Prize

Browse more biographies

William Walker

Russell Earl Marker

Roald Hoffmann

JJ Thompson’s Discovery of Electron: Cathode Ray Tube Experiment Explained

Table of Contents

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Cathode Ray Experiment

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What is a Cathode Ray Tube?

Thomson’s First Cathode Ray Experiment

Thomson's Cathode Ray Second Experiment

Thomson's Third Experiment

Later Developments

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British physicist J.J. Thomson announces the discovery of electrons