Vacuum ultraviolet absorption spectra of binary rare gas mixtures and the properties of heteronuclear rare gas van der Waals molecules

Abstract

Vacuum ultraviolet absorption spectra of binary rare gas mixtures Xe/X (X=He, Ne, Ar, or Kr) and Kr/Y (Y=He, Ne, Ar, or Xe) near each of the first two resonance lines of Xe i and Kr i, respectively, have been photographed at high resolution by a 6.65 m spectrograph with a rare gas continuum as background source. The overall formation of spectral features near a resonance line is predominantly towards short wavelengths, and the degree to which discrete bands form near a resonance line generally increases with increasing atomic weight of X or Y. Partial interpretations of the absorption spectra are given in terms of transitions within the heteronuclear rare gas van der Waals molecule XeX or KrY, from the bound ground electronic state (Ω=0) to bound or free excited electronic states (Ω=0,1). Bound excited electronic states are found for KrXe near the first resonance levels of Xe i and Kr i, and for KrXe and ArXe near the second resonance level of Xe i.