THE INFRARED SPECTRUM OF CARBON MONOXIDE IN CO–He MIXTURES AT HIGH PRESSURES

The 1–0 and 2–0 infrared bands of carbon monoxide were measured in CO–He mixtures at pressures up to 3 000 atm at 295 °K. Extrapolation of the integrated intensities of the bands gave the absolute intensities, Γ01 = 2 686 ± 44 and Γ02 = 9.29 ± 0.27 cm2 per mole. A slight increase in the band intensities with pressure is due to apparent induced absorption. A moment analysis of the bands, as proposed by Gordon, shows the presence of a torque due to intermolecular forces which hinders the molecular rotation; the magnitude of the torque derived from the analysis varies linearly with the density of the perturbing gas.