Size-quantization in extremely small CdS clusters formed in calixarene LB films

CdS nanoparticles have been formed within Y-type Langmuir-Blodgett (LB) films of cadmium salts of calix(8)- and calix(4)-arene by reaction with H2S. UV-vis absorption spectra of the LB films, measured at room temperature, show well-resolved transitions between size-quantization levels in CdS clusters. The size of the CdS particles, obtained by Gaussian fitting of the experimental spectra, is 1.5 +/- 0.3 nm, which is much less than those reported for fatty acid LB films. The particle size does net depend either on the type of calixarene or the number of LB layers. LB films were also characterised by X-ray diffraction and ellipsometry which show the film thickness do not change substantially after treatment with H2S. The mechanism of CdS nanoparticles formation is discussed. (C) 1998 Published by Elsevier Science S.A. All rights reserved.