Theoretical study of the collision-induced fundamental absorption spectra of N 2-N 2 pairs for temperatures between 77 and 297 K

Abstract

A procedure is presented for the analysis of the collision-induced fundamental absorption of pairs of N 2 molecules on the basis of quantum lineshapes computed from an accurate isotropic potential and multipole-induced dipole functions up to the hexadecapole term. The lineshape parameters were those obtained by Borysow and Frommhold from quantum computations of the far infrared collision-induced absorption of N 2. Because most of the other parameters appearing in the theoretical models for the various induced dipole-moment components are now known from independent measurements with reasonable accuracy, we compare the theoretical results for the absorption, calculated without the introduction of adjustable parameters, to the recent experimental results. We conclude that although the overall agreement for all the temperatures considered is good, small systematic differences especially in the wings of the band remain. These differences can be reduced somewhat by varying the magnitudes of the input data but not completely reconciled. Several additional mechanisms that can affect the wings of the band are discussed briefly.