TOWARDS MONODISPERSE SEMICONDUCTOR CLUSTERS - PREPARATION AND CHARACTERIZATION OF SIMILAR-TO 13-ANGSTROM THIOPHENOLATE-CAPPED CDS CLUSTERS

We report that two 10-angstrom [Cd20S13(SPh)22]-8 clusters may be fuse d together to form a 13-angstrom CdS cluster, which shows a sharp abso rption peak at 370 nm and a luminescence peak at 390 nm. This is suppo rted by the concentration dependence of the absorption spectra, the lu minescence-excitation spectra, the capillary zone electrophoresis sepa ration, the electrochemical measurement, and the powder X-ray data. Th is cluster fusion process occurs naturally in solution at high concent rations of [Cd20S13(SPh)22]-8. It can also be induced electrochemicall y by a two-electron oxidation process. We also show that capillary zon e electrophoresis and electrochemical synthesis are two useful new tec hniques for obtaining monodisperse CdS clusters. Their potentials and limitations are discussed.