Excited States of Solid Ar: H

Abstract

Excitation energies for the $1s-2p$ and $1s-2s$ transitions of a hydrogen atom as a substitutional impurity in solid argon have been calculated as a function of nearest-neighbor distance. A tight-binding treatment using Schmidt-orthogonalized wave functions is used to obtain the first-order shift from the atomic absorption energies. Overlap of atomic wave functions is taken into account through terms of second order, and three-center contributions are evaluated explicitly. The additional changes in the energies due to van der Waals interactions are obtained by a variational technique. Excitation energies for the $1s-2p$ and $1s-2s$ transitions are found to be 10.6±0.2 and 12.3±0.2 eV, respectively, for a nearest-neighbor distance of $7.0a_0$. The former gives good agreement with recent experimental observations.