Pressure broadening of CO infrared lines perturbed by H2 and He

Abstract

We present results of infrared linewidth measurements at low and room temperatures for CO diluted in H₂ and He using a tunable diode laser in the 4.7 μm spectral region (CO fundamental band). Information on the intermolecular potential is obtained by comparison with results of dynamical calculations. In the case of CO–H₂ pressure broadening (PB), data are compared to direct measurements of inelastic cross sections by infrared–infrared double resonance and to ab initio quantum calculations. In the case of CO–He, experimental PB coefficients are compared to theoretical cross sections derived from two ab initio potential energy surfaces.