Excitation of Molecular Rotation-Vibration by Electron Impact

Abstract

The integral equation for the scattering of an electron from a symmetric diatomic molecule is solved approximately to obtain the effective interaction integral between the electron and the molecular vibrationrotation, neglecting polarization and exchange. This interaction depends on the difference of phase of the incident wave function between the two nuclear centers and thus on the momentary direction and magnitude of the internuclear radius vector. From this interaction function the effective cross sections for rotation-vibration excitation are computed and, by various sum rules, a closed formula for mean loss of energy of the electron to molecular rotation-vibration is obtained. This is compared with the corresponding loss of energy of the rebounding electron to the motion of the center of gravity of the molecule. These two quantities are shown to be the same order of magnitude, their ratio changing from $\frac{1}{3}$, for very small equilibrium internuclear distance, to 1, for very large internuclear distance.