Collision-Induced Vibrational and Electronic Spectra of Gaseous Oxygen at Low Temperatures

Abstract

The infrared fundamental band and the five strongest near-infrared and visible electronic bands of gaseous oxygen were studied from 90 to 115 K with path lengths up to 140 m in two low-temperature multiple-traversal absorption cells. The profile of the fundamental band is in good agreement with the theory of quadrupole-induced absorption except for a low-intensity residual in the Q-branch region. Although the electronic bands are less amenable to complete analysis, the general validity of a Boltzmann relation in their intensity distributions confirms their collision-induced nature. The temperature variation of the integrated band intensities is indicative of quadrupole induction for the fundamental and of overlap induction for the electronic bands; a somewhat too sharp rise at low temperatures may be due to the neglect of the quadrupole–quadrupole coupling in evaluating the pair distribution function.