Photoionization studies of the Kr2 and Ar2 van der Waals molecules

Abstract

The photoionization efficiency curves of the Kr₂ and Ar₂ van der Waals dimers were obtained with the molecular beam technique in the wavelength ranges 850–965 Å (12.848–14.586 eV) and 750–855 Å (14.501–16.531 eV), respectively. The ionization potential of Kr₂ was found to be 12.87±0.015 eV (963.7±1.2 Å), which agrees with the value obtained by Samson and Cairns. The ionization potential of Ar₂ was found to be 14.54±0.02 eV (852.7±1.2 Å). Using the known ground state dissociation energies of Kr₂ and Ar₂, the dissociation energy of Kr⁺₂, D₀(Kr⁺₂), is deduced to be 1.15±0.02 eV and that for Ar⁺₂, D₀(Ar⁺₂), is 1.23±0.02 eV. The photoion yield curves of Kr₂ and Ar₂ are compared with that of Xe₂. Prominent autoionization structure was observed to correspond to Rydberg molecular states which are derived from the combination of a normal and an excited atom in the 4p⁵ns (or 4p⁵nd) configuration for Kr and 3p⁵ns (or 3p⁵nd) configuration for Ar.