Momentum transfer in electron—polar-molecule collisions: Results of semiclassical perturbation scattering theory

Abstract

Semiclassical perturbation scattering theory is applied to electron---polar-molecule collisions, assuming a pure charge-dipole interaction potential. Cross sections for momentum transfer are given in terms of dimensionless parameters involving the moment of inertia and dipole moment of the target, and the mass, charge, and energy of the projectile. A range of these parameters is explored corresponding to collisions at energies above 0.1 eV for most molecules. For large values of the dipole moment, the momentum transfer is much smaller than the prediction of the first-order Born approximation, and involves significant contributions both from elastic scattering and from transitions with large values of $|\ensuremath{\Delta}j|$. The behavior of the cross section as a function of the rotational quantum number $j$ is found to obey a simple scaling rule.