Correlation between the Spin State and Structure ofSelf-Trapped Excitons in Alkali Halides

抄録

In order to clarify the origin of the preferential relaxation of singlet self-trapped excitons (STEs) into the on-center configuration in alkali halides, we have studied variation of exchange splitting energy along the relaxation path from the on-center to the off-center configurations using a simple phenomenological model. Estimated exchange energy is several tens of meV both at the on-center and off-center configurations, and takes its maximum in between. It provides a larger potential barrier intervening between the on- and off-center minima for the singlet STE than that for the triplet STE. This will inhibit the singlet STE to be relaxed into the off-center configuration.