POLAR-CENTER PHASE NUCLEI IN HE-IRRADIATED CUO SINGLE-CRYSTALS()

Irradiation of various single-crystal CuO faces [ac,bc,(110)] with 4.6 -MeV He+ ions has been found to result in reduction of CuO to Cu2O and Cu on the irradiated and unirradiated sides, lifting of forbiddenness from optical transitions in the [CuO4](7-) electron center in the 0.7 -0.95-eV energy range, a change in dichroism near the bands correspond ing to transitions in the hole centers, [CuO4](5-), and electron cente rs, [CuO4](7-), as well as in a resonant increase of absorption at 0.9 5-1.30 eV with an unusual polarization dependence. The results of Heirradiation of CuO single crystals are discussed in terms of a model o f the nucleation of the phase of polar (electron and hole) centers in copper-oxygen systems. (C) 1998 American Institute of Physics. [S1063- 7834(98)00603-0].