An electron spin resonance study of photoproduced trivalent iron and divalent vanadium in silver chloride

Abstract

A method is described which allows Fez+ and VS+ to be formed in the same specimen of silver chloride. Exposure to blue or to red light produces Fe3+ and V2+. The effect of blue light is explained in terms of hole capture by Fez+ and electron capture by V3+ whereas that of red light is explained in terms of a charge-transfer absorption by the trivalent forms of iron and vanadium. A re-arrangement in the environment of FeS+ occurs on warming to about 203 "K. After blue irradiation a t 93 "K some of the Va+ is believed to be associated with two silver-ion vacancies. A re-orientation of the vacancies is observed on warming to about 110 and a t about 150 OK a further re-orientation takes place and one vacancy is removed. Photoproduced Fe3+ and Va+ are stable a t 93 OK. At room temperature they decay at the same rate with a half life which is of the order of minutes.

Anomalous Behavior of Electron Spin Resonance in KxC60 Film Prepared by Electrochemical Method

“…In fact, the difficulties in reproducibility reported by these earlier authors may well have arisen from lack of control of electron traps. That such traps can play a major role has been illustrated by an experiment on AgCl crystals doped with both Fe2+ and V3+ (Cheema and Smith 1970), in which the Fe" ion acts as a trap for photoholes while the V3+ traps photoelectrons.…”