Electron Energy Exchange Research Articles

ENERGY TRANSFER IN MOLECULAR CRYSTALS AND IN DOUBLE MOLECULES

The theory of the transfer of electronic energy between two molecules, or between two parts of a "double molecule", is discussed for the case in which vibrational quanta are present. The results are obtained for two limiting cases of weak and strong electronic interaction. Some of the phenomena occurring in the intermediate region are discussed qualitatively. With the aid of these results the spectra of biphenyl, diphenylmethane, and dibenzyl have been analyzed, and the electronic energy exchange parameter has been determined for each. These data are compared with similar data on durene crystal and the paracyclophanes. The electronic energy exchange parameter is given approximately correctly by considering the interaction of electronic transition dipoles except for very close and for very distant molecules.

Electron bunching and energy exchange in a traveling-wave tube

A physical picture of electron-wave interaction, electron bunching, and energy exchange in the traveling-wave tube is obtained by a study of the problem of electrons moving in a traveling electromagnetic wave of constant amplitude. This very simple analysis results in an easily understood qualitative description of the details of the interaction mechanism at large signal within an operating traveling-wave tube.

On Collision Problems Involving Large Interactions

Many collisions, particularly those in which there is an exchange of electronic energy from one atom or molecule to another, involve interactions between the colliding bodies, which (being treated as perturbations) are too large to be handled by the ordinary Born method. A method is given for the treatment of such problems. Two cases must be distinguished, that of good and that of poor resonance, resonance being good if the transition which takes place at the collision does not involve the transfer of much energy from internal energy to relative translational energy, or vice versa. The case of good resonance is handled by Dirac's perturbation method (variation of constants), and the probability that a transition take place at a collision of given distance of closest approach found in terms of the perturbation (interaction) matrix component for that collision. In the case of poor resonance, we first assume the two atoms or molecules are held at a fixed distance from each other, and apply the perturbation due to the interaction between them constructing potential energy curves as a function of the distance, as if the whole system were a large molecule. We then allow the translational motion to take place. This introduces further perturbations, which in the case of poor resonance are always small, so that relatively few transitions will occur. Since the amount of energy which we may have transferred from internal to translational, or vice versa, and still have the case of good resonance may be determined in special cases as a function of the distance of closest approach, we may tell in any special case how close the two molecules or atoms must come to each other in order for there to be a transition at the collision. Thus a radius of action can be found. In general it is concluded that if the transition is to take place with a large radius of action (compared with kinetic theory radii), then less energy can be transferred from internal to translational, or vice versa, than has hitherto been supposed.