LINEAR AND NONLINEAR TRANSMISSION OF CUXS QUANTUM DOTS

CuxS nanocrystals (NC's) are reported. The samples are prepared by a CdS-to-CuxS chemical conversion from the glasses originally containing CdS NC's. A room-temperature linear absorption of the converted samples shows several well resolved peaks with spectral positions from red to blue. These spectral features are explained by size quantization within CuxS NC's (similar to 4 nm radius) with different copper deficiency [x is in the range from 1.8 (digenite) to 2 (chalcosite)]. A strong bleaching of the samples with a 3-ns relaxation is observed in the pump-probe measurements. A high value of the third-order nonlinear susceptibility (similar to 10(-7) esu) is derived from the nonlinear transmission spectra. (C) 1995 American Institute of Physics.