Temperature dependence of line mixing effects in the stimulated Raman Q-branch of CO in He: A further test of close coupling calculations

Abstract

The fundamental isotropic Raman Q-branch of CO has been recorded using Raman loss spectroscopy for mixtures with helium at low temperatures (77–195 K). Accurate close coupling calculations of both diagonal and off diagonal (line coupling) cross sections have been performed starting from one of the best available potential energy surfaces [T. G. A. Heijmen, R. Moszynski, P. E. S. Wormer, and Ad van der Avoird, J. Chem. Phys. 107, 9921 (1997)]. Predictions are in good agreement with Q-branch Raman data. These results, which corroborate previous analysis based on IR absorption data, are a further test of the adequacy of the close coupling formalism for the prediction of line shapes in a rather wide range of physical situations (pressure, temperature, type of spectroscopy…), when an accurate potential exists.