On the inversion spectra ofNH3andND3

Abstract

When the dipole-dipole interaction energy of two polar molecules is comparable to their thermal energy during a binary collision, there is a net orientation of the two dipoles towards each other. The impact theory for the inversion bands of ${\mathrm{NH}}_{3}$ and ${\mathrm{ND}}_{3}$ is investigated in order to assess the implications of such orienting collisions. This is done by retaining cross sections which involve odd powers of the interaction Hamiltonian and results in a simple modification of the formula for the band shapes due to Ben-Reuven. A strict procedure for comparing the theory with experiment is described and applied to available data for ${\mathrm{NH}}_{3}$.