Photogeneration of ions via delocalized charge transfer states. II. HX2− (X=Cl,Br,I) in rare gas matrices

Photolysis of HX (X=Cl,Br,I) doped rare gas matrices at excitation energies well below direct ionization of the solids is shown to yield efficient formation of hydrogen bihalide anions, HX2−. The formation dynamics of these ions is ascribed to a charge separation process initiated by optical access of the delocalized charge transfer states. The vibrational spectra of HX2− are presented and compared with previous work on M+⋅⋅⋅(HX2)− ion pairs, and the isoelectronic triatomic rare gas hydride cations.