Optical detection of magnetic resonance in AgCl1-xBrx

ODMR studies are reported for crystals of AgCl 1-x Br x with x varying from approximately 0 to 0.3. For x=0.001 the ODMR spectrum at 4K shows resonances due to self-trapped holes which may be represented as (AgCl 6 ) 4- , nearly free electrons, self-trapped excitons which may be represented as (AgCl 6 ) 5- , and excitons trapped at bromine sites which may be represented as (AgCl 5 Br) 5- . At 1.6K the intensity of the spectrum of (AgCl 6 ) 5- falls to a very low value and the spectrum of (AgCl 5 Br) 5- grows. The origin of this effect is discussed. With increasing x the ODMR spectrum becomes increasingly dominated by excitons trapped in complexes containing increasing numbers of bromines until at x=0.3 the principal centre present is (AgBr 6 ) 5- . The variation of the g-value of nearly-free electrons with x is reported.