LINEAR AND NONLINEAR TRANSMISSION OF CUXS QUANTUM DOTS

CuxS nanocrystals (NC's) are reported. The samples are prepared by a C dS-to-CuxS chemical conversion from the glasses originally containing CdS NC's. A room-temperature linear absorption of the converted sample s shows several well resolved peaks with spectral positions from red t o blue. These spectral features are explained by size quantization wit hin CuxS NC's (similar to 4 nm radius) with different copper deficienc y [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 pum p-probe measurements. A high value of the third-order nonlinear suscep tibility (similar to 10(-7) esu) is derived from the nonlinear transmi ssion spectra. (C) 1995 American Institute of Physics.