Energy loss by slow electrons and by slow atoms in a molecular gas

Scattering of electrons, atoms, and ions by linear, symmetric-top, and asymmetric-top molecules is considered in the adiabatic-rotation approximation. The energy-loss rate or the stopping cross section, defined by multiplying the cross section by the excitation energy and by summing over final states, is independent of the initial rotational state. Thus, an average over the rotational distribution is independent of the rotational temperature of the gas