Picosecond transient gratings in CdS1−xSex mixed crystals

Abstract We performed transient grating experiments to study various relaxation processes of localized excitons in CdS 1 xSex mixed crystals. At low temperatures we observe a strong nonlinear response, spectrally in the localized states. We measured the phase relaxation time of localized excitons with a correlation technique. At low excitation levels we found long phase relaxation times of 75 ps. In a three beam configuration of a transient grating experiment we investigated the recombination as well as the diffusion of excitons within the localized states. We observed a reduced mobility compared to the mobility of free excitons in the pure compounds and found diffusion coefficients D cm 2 / s .