COLLISION-INDUCED ABSORPTION BY H-2-HE PAIRS IN THE H-2 FUNDAMENTAL-BAND AT 78-K AND 298-K

Measurements of collision-induced absorption spectra in the H2 fundamental band are reported for gaseous mixtures of hydrogen and helium at temperatures of 78 and 298 K and frequencies from about 3900 to 5200 cm-1. Spectral line shapes are calculated from the fundamental theory with the isotropic interaction approximation, which has been successful in all previous comparisons of the kind for pure hydrogen and hydrogen-rare-gas mixtures. In the present case, however, the comparison of measured and calculated absorption profiles suggests that small differences between theory and measurement may exist for H2-He in the H2 fundamental band, which are marginaly greater than the combined uncertainties of theory and measurement. Presumably, these are due to the neglect of the anisotropy of the interaction; the H2-He system in the H2 fundamental band is more sensitive to the anisotropy of the interaction than the systems and bands studied previously. © 1995 The American Physical Society.