Hot Excitons in Highly Excited CdS

Hot exciton distributions, as much as 30°K in excess of the He ambient, are observed in optically pumped CdS. The effective exciton temperature is determined by analyzing the luminescence line shape for $E_x-2\mathrm{LO}$ recombination of free excitons. The exciton state is found to remain a viable excitation up to the maximum pump intensity of ${10}^7$ W/${\mathrm{cm}}^2$, with the only observed response to the increasing pump power being a rise in effective exciton temperature.