Optical Absorption of Self‐Trapped Holes in AgCl and AgBr

In AgCl crystals doped with V3+, Cr3+, Fe3+, Ni2+, Cu2+, and chalcogen an infrared absorption at 9200 cm−1 is measured after irradiation at 20 °K. By comparison with ESR measurements on these crystals the infrared absorption can be assigned to holes trapped at lattice cations (Ag2+). The localization of the holes at lattice cations is explained by the valence band structure of silver halides and a Jahn‐Teller effect of the 4d9 configuration. AgBr crystals doped with V3+ or Cr3+ show after irradiation at 20 °K an infrared absorption at 7100 cm−1 with analogous properties as in AgCl.