The IR transmission spectrum of the irradiated and unirradiated doped corundum is analyzed in this paper. Three new IR peaks have been found. The peaks notably intensified in the spectrum of proton irradiated sample. However, in the spectrum of the sample irradiated Ž .y by an atomic reactor, the peaks of the doped Cu sample notably intensified only. It shows that the OH vibration and cation void in the crystal relate the peaks. It is concluded that the doping Cu in the crystal would affect seriously the crystal quality. q 2000 Elsevier Science S.A. All rights reserved.