Photoionization of ArKr, ArXe, and KrXe and bond dissociation energies of the rare gas dimer ions

Abstract

The relative photoionization cross sections for the heteronuclear rare gas dimers ArKr, ArXe, and KrXe are reported at a wavelength resolution of 0.15 to 0.28 Å in the energy region between the molecular ionization threshold and the atomic 2P°1/2 ionization limit of the lighter rare gas atom. The dimer ionization potentials are 13.484±0.015 eV for ArKr, 11.968±0.012 eV for ArXe, and 11.763±0.011 eV for KrXe. Combining these values with the known values of the atomic ionization potentials and the neutral ground state dissociation energies yields values for the A 2Σ+1/2 ionic ground state dissociation energies of 0.528±0.015 eV for ArKr, 0.176±0.012 eV for ArXe, and 0.385±0.011 eV for KrXe. Molecular Rydberg structure in the region between the atomic fine structure thresholds is analyzed in terms of Rydberg series converging to the B 2Π1/2 or D 2Σ+1/2 states of the dimer ions. Molecular Rydberg structure in other regions of the spectrum is extremely complex and, in many cases, long vibrational progressions are observed that are only partially analyzable with the present resolution. Tables are presented summarizing the best experimental values of bond dissociation energies for the ground and excited states of all of the homonuclear and heteronuclear rare gas dimer ions.