Subpicosecond dynamics of confined excitons in CuCl nanocrystals

We performed subpicosecond pump-and-probe measurements of CuCl nanocrystals at 77 K using a UV pump light of moderate intensity and high repetition rate and also a UV white probe light. For CuCl nanocrystals embedded in a glass matrix and in an NaCl matrix, we compare the temporal behavior of the non-linear change in the confined exciton absorption band induced by the existence of one exciton per nanocrystal. The decay time of the non-linear change is found to be much faster in the glass matrix than in NaCl, reflecting shortening of the exciton lifetime due to the photofatigue effect.