Pseudopotential study of the self-trapped exciton in rare-gas solids

The Rydberg series of the excited electron of the self-trapped exciton in rare-gas solids (Ar, Kr, and Xe) are studied using the pseudopotential approach of Bartram, Stoneham, and Gash. The original form of the ion-size correction is replaced by an alternative one which spreads out the effect over the ionic sphere in order to obtain more realistic energies for some of the symmetries of the state. The results are in good agreement with recent measurements of transient optical absorption of the self-trapped exciton, as well as of the isolated $R_2^{*}$ molecules. It is tentatively proposed that the higher-energy luminescence band of rare-gas solids originates from an orbital state distinct from that of the lower-energy emission band.