Magnetic Circular Polarization of Luminescence from Self-Trapped Excitons in Alkali Halides

Strong magnetic circular polarization has been observed in many of the intrinsic recombination transitions from a number of alkali halide crystals. The measured $g$ factors, $g\approx 2$, confirm the assignment that these transitions originate in triplet states of the self-trapped exciton. An analysis based on field-induced mixing of the $B_{2\mathrm{u}}$ and $B_{3\mathrm{u}}$ levels of the zero-field split-triplet state is consistent with the field and temperature dependence data for bromides and iodides.