Collision-induced spectra of hydrogen in the first and second overtone regions with applications to planetary atmospheres

Abstract

The pressure-induced spectra of hydrogen in the regions of the first and second overtones have been recorded with an absorption path length of 137 m in the temperature range 85 to 116 K. For pure hydrogen the structure and integrated intensities of the bands are in good agreement with calculations based on the theory of quadrupole induction, except that the second overtone shows evidence of a small amount of overlap induction. The enhancements of the first overtone in hydrogen + argon and hydrogen + nitrogen mixtures have structures in accordance with quadrupole induction, but the calculated intensities are somewhat too high. The enhancement of the first overtone in the hydrogen + helium mixture was too weak to be recorded. Calculated profiles for the third overtone in pure hydrogen are given. The implication of these measurements for studies of the hydrogen and helium content of planetary atmospheres is discussed.