Optical detection of impurity NMR in the magnetic circular dichroism of F centres in alkali halide crystals

Nuclear magnetic resonance of thallium impurities has been detected by monitoring the magnetic circular dichroism of the absorption of F centres produced by room temperature X-irradiation under optical pumping conditions in Tl-doped KCl and RbCl crystals. In addition, electron nuclear double resonance signals of the F centre ligands were detected without microwaves. The observed effects are caused by hyperfine coupling of the F centres to the surrounding nuclei. F centres are probably produced with a spatial correlation to the thallium impurities.