The Far Ultraviolet Absorption Spectra and Ionization Potentials of H2O and H2S

Abstract

The absorption spectra of H2O and H2S in the region below 1600A have been found to consist of various electronic series accompanied by comparatively little vibrational structure. The electronic series conform fairly well to Rydberg formulas the limits of which give 12.56±0.02 and 10.42±0.01 volts, respectively, for the ionization potentials of these molecules. The analysis fits in very well with Mulliken's prediction that the bands should be due to the excitation and removal of a nonbonding electron localized near the oxygen or the sulphur atom. A tentative rotational analysis given for some of the bands in H2S indicates that the moments of inertia suffer little change by the excitation. Suggestions with regard to plausible atomic term series related with the molecular series are put forward.