The pressure broadening effect of argon, carbon dioxide, and hydrogen chloride on the ν3 band of HCN has been measured. The broadening effects of the different gases are found to be in qualitative agreement with the theory. Of particular importance is the observation of an oscillatory behavior in the J dependence of the line half-width for HCI+HCN. This oscillatory behavior is explained as due to a dipole-dipole interaction for which the large difference between the rotational levels of perturber and absorber molecules causes some levels to be in resonance while others are not.
ROBERT J. THIBAULT, ARTHUR G. MAKI, and EARLE K. PLYLER, "Broadening of the ν3 Lines of HCN Due to Argon, Carbon Dioxide, and Hydrogen Chloride," J. Opt. Soc. Am. 53, 1255-1258 (1963)