Abstract
The exciton-phonon interaction in a two-dimensional (C2H5NH3)2CdCl4 single crystal was studied by investigating the low energy tail of the first exciton absorption band in the temperature range of 100--440, K. The tail spectrum for different temperatures obeys the Urbach rule with small steepness parameters. From the analysis of those tails, it is determined that the steepness coefficient σ 0 is 0.60 and the exciton-phonon coupling constant g is 2.1. These indicate that the exciton-phonon interaction in (C2H5NH3)2CdCl4 is strong and the free exciton relaxes to the self-trapped exciton state. The electronic nature of the excitonic transition is discussed on the basis of the results in the present work.
