Collision-induced absorption in gaseous mixtures of nitrogen and methane

Abstract

The collision-induced absorption spectra of nitrogen–methane gas mixtures have been measured in the spectral region below 400 cm −1 at four temperatures, namely, 212, 179, 149, and 126 K. The measurements have involved the use of Fourier-transform infrared and microwave techniques as well as a far-infrared laser operating at 84.2 and at 15.1 cm −1 . These are compared with a theoretical line shape obtained from a convolution of free rotational spectra and a translational component as determined from information theory. The calculated spectra show good agreement with the experimental results only in the lower frequency region. An important feature of the theoretical development is that no adjustable parameters need be introduced.