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Terrible feelings and Hitler is made Chancellor of Germany


Proof of the accepted chemical theory of the structure of benzene
Edward Teller Scientist
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Now I want to talk about my paper with Porner and Northeim. We asked the question- If Pauling is right, as you believed he's obviously right and he indeed is, what happens if you do not add these two wave functions but subtract them? That will give rise to a higher energy of benzene, to an excited state of, of benzene and one should see that state in the spectrum of benzene and we found it. It is a state in the near ultraviolet. Not being in the visual spectrum, it leaves benzene colorless, but has some peculiar properties. And here I want to use this example as another illustration of the correspondence principle applied to molecules. In quantum mechanics, the transition from a state representing the sum of two states to a state representing the difference of the two states, having different energies, corresponds in classical theory to a motion and oscillation of the electrons. The transition between these two states gives rise- corresponds to an oscillation of the electrons between one Kekulé formula and the other Kekulé formula. Now from that a number of interesting points follow connected with the symmetry of the problem. The Kekulé formula with three double bonds in a triangle and three s- single bonds in another triangle gives a center of gravity of directed charges smack in the middle. If I go from one Kekulé formula to the other, the average position of the electrons is not changed. Therefore in a simple form the transition cannot occur. It is not connected with an oscillation of electric charges, it will not emit or absorb light - it's a forbidden transition. Then why do we see it? The answer is simple: here is the molecule, six sides, one and four here. Now let the molecule vibrate like this. The vibration causes a dipole moment to appear because in the one Kekulé formula there is a double bond here and a single bond here. In the other Kekulé formula there is a single bond on top and a double bond here and there are more electrons in the double bond than in the single bond. And if the molecule vibrates like this, then this change in dipole moment is no longer compensated by the change, by similar changes in dipole moment between this pair and this pair of bonds. The vibration causes the transition to become weakly permitted. A conclusion from this is a different behavior of the molecule; not only is the transition weak, but its vibrational structure is different. In an allowed transition you can see vibrations in which for instance the hexagon gets bigger and smaller but does not change its symmetry - for an allowed transition. For a forbidden transition you will never see the electrons change unless a vibration which causes a dipole moment, unless that too is excited. And that is precisely the structure that we found for that weak transition. That was a quantitative proof of the accepted chemical theory of the structure of benzene, and I want to add one political point.

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: 5 minutes, 42 seconds

Date story recorded: June 1996

Date story went live: 24 January 2008