Abstract
Weblike aggregates of coalesced Si nanocrystals are prepared by the Laser Vaporization-Controlled Condensation (LVCC) method. Upon excitation with visible or UV light, the Si nanocrystals show red photoluminescence whose multiexponential time decays are characterized by lifetimes that range from 20 - 80 mu s, depending on the emission wavelength. This red emission can be quenched with electron acceptors like 1,4-dinitrobenzene and WO3 nanoparticles. The quenching rate constants obtained from a Stern-Volmer analysis are 7.65 x 10(6) (Ms)(-1) and 14.1 x 10(6) (Ms)(-1) for 1,4-dinitrobenzene and WO3 nanoparticles, respectively. The quenching mechanism appears to proceed via an electron transfer from the CB band of the Si nanocrystals to the quenchers. (C)1999 Acta Metallurgica Inc.