Formation of CdS nanoclusters within LB films of calixarene derivatives and study of their size-quantization

Cadmium sulphide nanoclusters formed in Langmuir-Blodgett films of various calixarene derivatives were studied by means of UV-visible spectroscopy, AF M, TEM and electron diffraction. It has been shown that calixarene cavitand s of different size yield a similar kind of CdS nanoclusters as characteris ed by the first exciton transition near 3.2 eV. In contrast to that, CdS cl usters formed within LB films of stearic acid or formaldehyde/2,6-dihydroxy benzoic acid copolymer have much lower exciton energy of 2.7 eV, correspond ing to greater CdS clusters. The value of 2 nm and 4 nm in diameter were ob tained, respectively, for CdS clusters in calixarene and stearic acid LB fi lms by using Ramakhrishna's results of diner calculations of the band struc ture. AFM and TEM results confirm the difference in size of those CdS clust ers. Electron diffraction data show that CdS nanoclusters have zinc blende structure rather than wurtzite, and the lattice parameters of 0.583 +/- 0.0 09 nm and 0.567 +/- 0.012 nm were obtained for the clusters formed within s tearic acid and calixarene matrices, respectively. (C) 1999 Elsevier Scienc e S.A. All rights reserved.