CU- PAIRS DEFECTS INTERACTION IN NAF CRYSTALS( AND OH)

The presence of Cu+ in OH- doped NaF crystal results in several new in frared absorption bands with similar to 0.2 cm(-) halfwidth at 100 K, and their relative intensities are strongly impurity concentration dep endent. Their assignments are not evident and are mostly attributed to different vibrational internal modes of the molecular OH- perturbed b y neighboring Cu+ ions.(1) We report the results of the temperature de pendence of several OH- sidebands around the 3737.8 cm(-1) 'free' OH- stretching mode. The temperature dependence reveals a different behavi our from already known OH- quasi free rotor in several cesium halides. (2) For the temperature range from 100 to 300 K, the free OH- halfwidt h shows a T-2 behaviour. While for three chosen absorption sidebands a re determined to be T-1.6, T-1.8 and T-2.5. The lack of observable the rmally stimulated depolarization current and electric field induced di chroism(3) indicates that the OH- is frozen-in, so it is also the same with the OH--Cu+ pairs.