Excitation of Molecular Vibrations by Electrons

Abstract

The cross section for the excitation of molecular vibration by electron impact is calculated for two cases: (1) On the assumption that a molecule interacts with an electron through the oscillating electric moment arising from the vibration, the cross sections of excitation and deexcitation are of the order $y^2·{10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ where $y·{10}^{-18\mathrm{}}$ c.g.s. unit is the matrix element of the electric moment associated with the vibrational transition. (2) For optically inactive vibration, an approximate estimate of the cross section in the case of the ${\mathrm{H}}_2$ molecule is made by the method of distorted wave. The cross section is of the order 0.5·${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$ for electrons of a few volts. These results are compared with the experimental results on the probability of electron energy transfer to molecular vibrations.