Interaction of rare-gas-halide excimers with simple cryogenic liquids.

Abstract

A one-parameter theory for the energy shifts experienced by the electronic levels of dipolar rare-gas--halide excimers dissolved in liquid rare gases is presented. The theory, based on Onsager's solute-solvent interaction, yields good results for both diatomic and triatomic species. The radius of the Onsager cavity is found to be dependent only on the dielectric characteristics of the solvent while the strength of the reaction electric field appears to be determined exclusively by solute molecular properties, namely, the dipole moment and the polarizability. These empirical rules lead to the determination of a fundamental constant, characteristic of these interactions, which is conserved to within approximately 2% for the materials studied. In addition, the use of this constant in the description of the interaction, which has the units of a polarizability, permits a drastic reduction of parameters, from one cavity radius per liquid host, to only a single fundamental constant. From this analysis, very simple expressions for the cavity radius and the reaction electric field are deduced for argon, krypton, and xenon.