ULTRAVIOLET AND INFRARED-SPECTROSCOPY OF OH- CU+ DOUBLE DOPED NAF/

Electronic and vibrational absorption spectra of OH- and Cu+ double do ped NaF are studied and compared with the same respective single impur ity doped host material. New ultraviolet and infrared absorption bands are found, which are supposed to be from a coupling effect of Cu+ -OH - defects. The infrared vibrational absorption of the OH- fundamental stretching mode, for uncoupled and coupled defects, were measured usin g a color center laser, with X cavity configuration and 0.2 cm(-1) res olution. The observation of second harmonic absorption are analyzed an d the ratio of overtone to fundamental reveals the existence of an ele ctric anharmonicity in addition to the usual mechanical one observed i n the Morse's potential model. Further measurements of thermally stimu lated depolarization current indicate a permanent orientational freeze -in of the Cu+ - OH- defect.