EPR spectroscopic investigations of metal halides doped with transitionhyphen;metal ions. I. Rhodium(III)hyphen;doped AgBr

摘要

An electron paramagnetic resonance (EPR) investigation of silver bromide doped with Rh3plus;ions has revealed that this impurity is an electronhyphen;trapping center during exposure. The photoreduction can be effected with whitehyphen;light exposures, but it is most efficient at 510 and 620 nm. The rhodium(II) photoproduct,lsqb;lpar;RhBr6rpar;4minus;lpar;Agvacplus;rpar;rsqb;, is a distorted covalent complex, and the EPR data indicate that this species has a2A1g(verbar;3z2minus;r2) ground state below 100deg;K, an effective2B1g(verbar;x2minus;y2) ground state between 100 and 220deg;K, and is dynamically distorting above the latter temperature. An attempt is made to explain this latter observation in terms of the thermally induced reorientation of the associated silverhyphen;ion vacancy about the Rh2plus;site.