Pico-second spectroscopy of highly excited CdSe and CdSI high density exciton system

Time-resolved luminescence spectra are measured at 4.2 K most in detail for CdSe under 531 nm pico-second pulse excitation. The M, P, and A-LO lines from high density excitons rise in intensity after pulse excitation, reach maxima, and then fall, the rise time being in a range of 100–600 psec and becoming faster with increasing excitation density. This time dependence is due to the light amplification effect by stimulated emission.