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.