Theory of exciton-population-induced nonlinear absorption in large microcrystallites

A model of excitons in large semiconductor quantum dots (R/${\mathit{a}}_{\mathit{B}}$≫1), together with ideas of Efros and Efros on exciton-mass-center quantization, is used to describe many-exciton states in materials with large exciton binding energy. In the light of this theory the recent pump-probe experiments of Gilliot et al. on CuCl dots are interpreted as nonlinear absorption induced by an average population of a few excitons per dot.