Heat pulse modulation of molecular crystal phosphorescence

Abstract

The modulation of low temperature (2°K) molecular crystal phosphorescence by submicrosecond duration heat pulses is discussed in connection with the study of rates of triplet energy transfer and trap thermalization. A phenomenological discussion of the dynamics of heat pulse propagation in molecular solids is presented and estimates of the thermal relaxation time of the lattice are obtained. It is suggested that these times are sufficiently short to permit investigation of the dynamics of exciton energy transport in molecular crystals. The details of the technique are discussed and results from several experiments are presented. Additionally, heat pulse modulation of the electron paramagnetic spin distribution of radiative triplet states is discussed and some preliminary results presented.