Effect of electron bombardment on a phase-inhomogeneous nanoscopic structure and the fundamental absorption spectrum of single-crystal CuO

The optical absorption spectra of single-crystal CuO bombarded with 5-MeV electrons exhibit reduced absorption in the region of the fundamental absorption edge at 17 eV, which corresponds to the b1g→eu transition with charge transfer in CuO46−. A simultaneous increase in absorption is observed in the middle infrared and in the region of high energies centered on 2.9 eV. The experimental results obtained are interpreted in terms of ideas on the phase-inhomogeneous nano-agglomorated structure in copper oxides that occurs as a result of the nucleation of polar centers (CuO45−, CuO47−) under electron bombardment.