LINEAR AND NONLINEAR OPTICAL-PROPERTIES OF CDSE MICROCRYSTALLITES IN GLASSES

We investigated linear and nonlinear properties of CdSe microcrystallites embedded in glass matrices and with radii ranging from 2 to > 12 nm. The transient absorption spectra measured by the femtosecond pump-probe method gave us information on the relaxation processes of the confined electrons and holes in the microcrystallites. When the microcrystallite radius is smaller than the excition radius, the optical transition between the quantized levels of an electron and of a hole is blocked by the existence of photoexcited carriers in these levels and in the shallow trap centers. In contrast, when the crystallite radius is larger than the exciton radius, relaxation of hot carriers with emission of phonons is observed, as in bulk crystals.