Low-temperature photophysics of crystalline AgCl

Free and trapped electrons, self-trapped holes Ag$\mathrm{Cl}_6^{}{}_{}{}^{-4\mathrm{}}$, and self-trapped excitons exist simultaneously in band-gap-irradiated AgCl at low temperatures and contribute to the AgCl luminescence. Small amounts of bromide impurity in AgCl promote the formation of a self-trapped exciton containing bromide which also radiates. The various centers are investigated through the luminescence, optically detected magnetic resonance, and level-anticrossing spectra of neat and bromide-doped AgCl.