COLLISION-INDUCED ABSORPTION BY H-2-H-2 AND H-2-HE PAIRS IN THE FUNDAMENTAL-BAND - AN EXPERIMENTAL-STUDY

Absorption coefficients for the collision-induced fundamental band of H2, in the pure gas and interaction with He, have been measured at 298 K between 3950 and 5300 cm-1. The spectra were recorded with a 3-m long absorption cell for gas pressures up to 51 bar for pure H2 and to 163 bar for H2-He mixtures. In both cases, we have obtained new experimental results for the intercollisional interference Q(1) and S(1) dips, concerning essentially their width and their relative intensity. For pure H2, our measurements of binary coefficients are in excellent agreement, except in the summit of the Q-branch (4200 cm-1) and in the high frequency wing (v ≥ 5200 cm-1), with results from a recent ab initio quantum calculation. For H2-He, the theoretical results at 300 K arising from another recent quantum calculation are notably larger than our experimental values over all of the spectral region under study. © 1990.