E. U. Condon

One-Electron Rotatory Power

It is shown that a single electron moving in a field of suitable dissymmetry can give rise to optical rotatory power in a medium containing molecules of this type. This effect is called one‐electron rotatory power and is in striking contrast to the models developed by Born, Oseen, Gray and others in which a dynamic coupling between several electronic oscillators is responsible for the rotatory power. The detailed calculations are carried out for the potential function, V=12(k1x2+k2y2+k3z2)+Axyz, which shows rotatory power both quantum mechanically and classically. Next it is shown how fields of this type may be adapted to an approximate description of the field in which the chromophoric electrons of a molecule move, the constants k1, k2, k3 and A being largely determined by the average charge on the different atoms of the molecule as found from additivity of dipole moments due to the bonds in the molecule. As illustrations of the theory absolute calculations are made for the contribution of the nitrite gr...

A Theory of Intensity Distribution in Band Systems

A theory of the relative intensity of the various bands in a system of electronic bands is developed by an extension of an idea used by Franck in discussing the dissociation of molecules by light absorption. The theory predicts the existence of two especially favored values of the change in the vibrational quantum numbers, in accord with the empirical facts as discussed by Birge.

The Franck-Condon Principle and Related Topics

A review of the historical development and present status of certain topics in molecular physics may serve as a reminder of the progress made in the past two decades. Let us recall that in 1925 there was no subject of nuclear physics, and high voltage equipment was almost non-existent except in the x-ray laboratories. About all that was known about cosmic rays was that the ionization increases in high balloon flights in the atmosphere and that its cause penetrates deeply into lakes. Nobody had heard of closed electron bands in a solid, and the word semi-conductor was essentially unknown.

Wave Mechanics and Radioactive Disintegration

After the exponential law in radioactive decay had been discovered in 1902, it soon became clear that the time of disintegration of an atom was independent of the previous history of the atom and depended solely on chance. Since a nuclear particle must be held in the nucleus by an attractive field, we must, in order to explain its ejection, arrange for a spontaneous change from an attractive to a repulsive field. It has hitherto been necessary to postulate some special arbitrary ‘instability’ of the nucleus; but in the following note it is pointed out that disintegration is a natural consequence of the laws of quantum mechanics without any special hypothesis.

Forced Oscillations in Cavity Resonators

Formulas are developed for calculation of the impedance of a cavity resonator when excited by a coupling loop or by a capacitative coupling.

Physics of the Glassy State. I. Constitution and Structure

Modern views of the constitution and structure of inorganic glasses are outlined. Materials used in glass making are classified according to their role as network formers and network modifiers. Evidence of structure from x-ray scattering is reviewed. Examples of linear and nonlinear dependence of specific volume on composition are presented, and the classical factors for composition dependence of heat capacity are related to quantum theory of specific heat.

The Theory of Complex Spectra II

Formulas for the relations between the energies of multiplets arising from the same electron configuration for all two-electron cofigurations up to ff and several cases of three-electron configurations are worked out following Slater’s method; Slater’s table of a’s and b’s being extended to cover f electrons. A systematic comparison of the known data with this first order perturbation theory shows poor agreement in many cases and good agreement in many. The theory predicts the observed alternation in the relative positions of singlet and triplet through S, P, D, F, etc. in the pp, pd, and pf triads, and the dd and df pentads. In general the p electron configurations fit very poorly; a uniform trend with atomic number is observed for p 3 and good fits are obtained for 4p3d in Ti III, V IV, and Cr V. For d electrons the theory fits very well in the first long period of the periodic table, and fairly well in the second. The 1 S of d 2 and the 2 D of d 2 s are predicted much higher than the levels assigned to those multiplets when such an assignment is made, d 3 fits well except for 2 P. An energy level table of La II is given as recently analysed by Meggers and Russell. Here we have complete 5d4f and 4f 2 configurations which fit the theory very well, these calculations having assisted in the assignment of some of the singlets and resulted in a rearrangement of singlet lines.

Physics of the Glassy State. II. The Transformation Range

The concept of fictive temperature as a means of describing nonequilibrium states of glass is described. Activation energies and the modern views of chemical rate processes are discussed in relation to the kinetics of the approach of these nonequilibrium states to equilibrium.

Quantum Mechanics of Collision Processes

By a collision will be understood the interaction of two or more of the entities with which atomic physics is concerned under such conditions that before and after the collision they are widely separated in space but during the collision they are close together. The entities which may take part in collisions include electrons, protons, photons, atoms and molecules. If photons were to be cnsidered the report would also need to treat of the entire problem of the interaction of radiation and matter. This is too much and so it is arbitrarily excluded. Certain other topics such as the Ramsauer effect, the collisions of two atoms and the polarization of the light emitted by atoms excited by an incident unidirectional electron beam are also left out of consideration. The report is thus intended simply to serve as an introduction to the simpler problems and to the method by which the more complicated problems are attacked.

Tunneling—how it all started

A personal account of the early history of tunneling and the contribution of Ronald W. Gurney.