ELECTRON-SPIN-RESONANCE STUDY OF RADICALS PRODUCED ON IRRADIATED CDS POWDER

ESR measurements were carried out for wurtzite (W) and zinc-blende (ZB ) CdS powders at 77 K under light irradiation. ESR signals at g = 2.00 4-2.035 were detected for each crystal structure. The signals decrease d on contact with 2-propanol and were assigned to trapped holes. The W CdS is active for oxidation reactions rather than the ZB CdS since th e formation of 2-hydroxy-2-propyl radical was clearly observed. Reduct ion of methylviologen was observed for some CdS powders. The differenc e in the photoinduced ESR spectra was discussed with the morphology of the particles obtained from transmission electron microscopy.