Nonlinear spectroscopy of phosphate glasses containing cadmium selenide nanoparticles

An investigation was made of the photoluminescence and differential absorption spectra of phosphate glasses containing embedded CdSe nanoparticles. These spectra were determined by the pump-and-probe method. The photoluminescence spectrum included a short-wavelength band resulting from direct recombination of electron — hole (eh) pairs and a long-wavelength band associated with carrier recombination via deep levels of defects. Two peaks, attributed to the 1S_e → 1S_3/2 and 1S_e → 2S_3/2 transitions, were observed in the short-wavelength photoluminescence band at high excitation rates. The kinetics of the differential absorption spectra was explained by saturation of the absorption of the exciton (eh) transitions and by the appearance, in the excited nanoparticles, of the absorption corresponding to two-pair (2eh) states.