TUNNELING THROUGH THE SELF-TRAPPING BARRIER IN RARE-GAS SOLIDS

The adiabatic potential surfaces for atomic-type and molecular-type self-trapped excitons are explicitly determined for all rare gas solids. The resultant barrier separating the free exciton from atomic-type and molecular-type self-trapped states is analyzed, determining the barrier height and the tunneling path length for a wide range of parameter combinations. The tunneling through the barrier is then described by means of the theory of multi-phonon non-radiative transitions. Restricting the possible paths to one along a single interaction mode the tunneling rate is optimized. The results are consistent with experiments.