Dynamical Aspects of Self-Trapping of 1s Excitons in KI

Abstract

The self-trapping time of 1s excitons in KI is directly measured for the first time by using the picosecond pulses of fifth harmonic (212.8 nm) of a Nd³⁺ : YAG laser, which is one-photon resonant to the 1s exciton. By observing the rise time of the E_x luminescence, the self-trapping time is estimated to be 100±50 ps. This self-trapping time is considered to be the time for the excitons to tunnel the adiabatic potential barrier. The self-trapping time and the barrier height, 30 meV, are compared with theoretical calculation and consistency of these values is discussed.