Identification of Shallow Electron Centers in Silver Halides

On the basis of the excitation-induced absorption spectra insilver halides doped with impurities, two kinds of shallow electron centers are identified. One is an electron bound at a silver interstitial ion and corresponds to the intrinsic electron center in silver halides. Addition of chalcogen impurities enhances the spectra of this origin. The other is an electron bound at substitutional divalent cations, the transition energy of which shifts systematically depending on the kind of impurity.