EPR spectroscopic investigations of metal halides doped with transition-metal ions. I. Rhodium(III)-doped AgBr

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Abstract
An electron paramagnetic resonance(EPR) investigation of silver bromide doped with Rh3+ ions has revealed that this impurity is an electron‐trapping center during exposure. The photoreduction can be effected with white‐light exposures, but it is most efficient at 510 and 620 nm. The rhodium(II) photoproduct, [( RhBr 6 ) 4− ( Ag vac + )] , is a distorted covalent complex, and the EPR data indicate that this species has a 2 A 1g (|3z 2−r 2>) ground state below 100°K, an effective 2 B 1g (|x 2−y 2>) ground state between 100 and 220°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 silver‐ion vacancy about the Rh2+ site.