Theory of line shape in pressure-induced absorption

Abstract

A quantum theory of line shape in pressure-induced absorption giving relatively simple results in closed form is developed. A flexible model correlation function satisfying certain general criteria is chosen and incorporated in a general quantum theory of absorption. Relations are derived for estimating the values of the time parameters in the correlation function in terms of known molecular parameters. The theory is applied to far infrared spectra: the translational spectrum of He–Ar, the well resolved S(0) rotational line of H2 at 77 K, and the unresolved rotational band of N2. In all cases, the theory fits the spectra and accounts for the spectral features.