Self-trapping of hot and thermalized excitons in solid xenon

The first direct measurement of the self-trapping rate, Γ_ST, of thermalized excitons in solid Xe is presented. The temperature dependence of Γ_ST is explained by thermal assisted tunneling through the self-trapping barrier separating free and self-trapped exciton states. The results agree with recent theories on self-trapping. The ratio of luminescence intensity of free and self-trapped states disagrees with the measured self-trapping rates and displays the role of self-trapping of hot excitons.