TIME-DEPENDENT LIGHT-ABSORPTION BY IMPURITY CENTERS

Light absorption by impurity centres with generation of charge-transfer excitons is considered. The static electric field produced by already existing excitons shifts the excitation energy of non-excited centres and, hence, the probability of their excitation. This dependence of the absorption cross-section of a centre on the spatial distribution of excitons results in the nonlinear behaviour of the system under strong pumping. Computer simulation of exciton generation and annihilation shows that stationary powerful light transmitted through a sample has a time dependent power.