a story lives forever
Sign in
Form submission failed!

Stay signed in

Recover your password?
Form submission failed!

Web of Stories Ltd would like to keep you informed about our products and services.

Please tick here if you would like us to keep you informed about our products and services.

I have read and accepted the Terms & Conditions.

Please note: Your email and any private information provided at registration will not be passed on to other individuals or organisations without your specific approval.

Video URL

You must be registered to use this feature. Sign in or register.


Going to Rome with Placzek to visit Fermi


The changing polarizability of carbon dioxide
Edward Teller Scientist
Comments (0) Please sign in or register to add comments
Now, a friend of mine, George Placzek, who drew my attention to the problem, he and I applied all this to the Selection Principle. Which vibration of a molecule will appear in the Raman effect and how will it appear? And again, I can best illustrate what we have done by a concrete example, one of my favorite molecules, carbon dioxide. It's simple enough so you can readily understand what you talk about. It still has the complexity to be a little less boring than the simplest examples. Here is a carbon dioxide molecule: carbon, two oxygens, on a straight line. Now consider two vibrations. This vibration, the carbon remains in the same position, the oxygens move up and dow- away and toward. And this vibration. The carbon moves up and down, relative to the two oxygens. If it- you give it a moment of thought, you will see that purely classically, what I describe to you as Raman effect, should behave quite differently in the two cases. Here, you might go from an easily polarized state to a less easily polarized state, to an easily polarized state, to a less easily polarized state. The polarizability changes, goes through a complete cycle. When the molecular vibration goes through a complete cycle, that's a simple thing that you would expect. And that corresponds to the case where, in the Raman effect, the vibration, this one, will be excited with a single quantum. But now, look at this. The carbon vibrates against the two oxygen atoms, oxygen atoms. Let the carbon start at the center, has a polarizability. It gets off the center and now it has a greater polarizability. It gets back to the center, it has the original polarizability. If it gets off the center, a greater polarizability, back to the original center, original polarizability. In a complete vibration, from here to here to here to here, the polarizability had two maxima, here and here, and two minima, when the carbon went through the central position. You will never see one quantum added to the original frequency of light, but only two quanta. Because half a vibration is enough to re-establish the original position- original polarizability. And therefore, the polarizability will change twice as many times per second. Then the complete vibration changes. This thing, this kind of idea, applied to vibrations and incidentally, which is the main thing Placzek and I did, applied to rotations - the rotational frequencies also can be imposed on the original frequency. That is what we did for a few years, few- quite a few months, at any rate. Almost all the two years I have been in Göttingen.

The late Hungarian-American physicist Edward Teller helped to develop the atomic bomb and provided the theoretical framework for the hydrogen bomb. During his long and sometimes controversial career he was a staunch advocate of nuclear power and also of a strong defence policy, calling for the development of advanced thermonuclear weapons.

Listeners: John H. Nuckolls

John H. Nuckolls was Director of the Lawrence Livermore National Laboratory from 1988 to 1994. He joined the Laboratory in 1955, 3 years after its establishment, with a masters degree in physics from Columbia. He rose to become the Laboratory's Associate Director for Physics before his appointment as Director in 1988.

Nuckolls, a laser fusion and nuclear weapons physicist, helped pioneer the use of computers to understand and simulate physics phenomena at extremes of temperature, density and short time scales. He is internationally recognised for his work in the development and control of nuclear explosions and as a pioneer in the development of laser fusion.

Duration: 4 minutes, 50 seconds

Date story recorded: June 1996

Date story went live: 24 January 2008