Interaction of spatially separated oxygen-vacancy centers in CaF2 crystals due to an excitation-induced short-time molecular bond

Electro‐physical and optical methods have been used to investigate oxygen–vacancy centers in CaF2:O2– crystals. The study revealed a new luminescence excitation band peaking at 4.27 eV. The excitation with the light from the region of this band is accompanied by electron transfer. It is found that the decay of luminescence is not exponential and is described by Becquerel's empirical law. New evidence has been obtained for thermostimulated depolarization associated with both ionic and electronic phenomena within the crystal. Activation energies for thermostimulated processes have been estimated. The results can be interpreted as providing evidence for the excitation‐induced short‐time molecular bond between spatially separated oxygen–vacancy defects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)