INDUCED INFRARED ABSORPTION IN HYDROGEN AND HYDROGEN - FOREIGN GAS MIXTURES AT PRESSURES UP TO 1500 ATMOSPHERES

Abstract

The pressure-induced fundamental infrared absorption band of hydrogen has been investigated in the pure gas and in hydrogen–helium, hydrogen–nitrogen, and hydrogen–argon mixtures for gas pressures up to 1500 atm. and temperatures in the range 80°–376°K. At the higher densities the rate of increase of the integrated absorption coefficient with density is anomalously large; this effect is interpreted in terms of finite molecular volumes. The Q branch has been shown to consist of three components Q_P, Q_q, and Q_R. The separation of the maxima in the low- and high-frequency components, Q_P and Q_R, depends on the perturbing gas and increases linearly with its density; the separation and relative intensities of the components are also strongly dependent on the temperature. It is proposed that this splitting of the Q branch is caused by the participation of the relative kinetic energy of the colliding molecules in the absorption process for collisions in the region of overlap forces. The Q_q component and the S lines show no splitting and are probably produced by collisions in the region of quadrupole interaction.