Spectral study of Ne⁺-bombarded crystalline MgO

Optical-absorption spectra are presented from 3.8 to 7.4 eV of the coloration produced in crystalline MgO by bombardment with 3-MeV Ne⁺ convering a fluence range from 10¹⁴ to 10¹⁷ ions cm^-2. Dose dependence of absorption at 5.0, 5.8, and 7.0 eV and of the integrated intensity of the F⁺-center ESR pattern are shown. Spatial profiles of coloration at 5, 6, and 7 eV are similar to the shape of the nuclear stopping power predicted by Lindhard, Scharff, and Schiott, suggesting that much of the coloration is related to displacement-type lattice damage. Normalized spectra show at high dose additional absorption on the high-energy side of the F-type band and absorption on the low-energy side of the first exciton-type transition. The latter is discussed in terms of perturbed excitons. Annealing to 600 ^∘{}C removes the intense F-type band and reveals a band at 5.8 eV. This band accounts for most of the additional, high-fluence-induced absorption observed on the high-energy side of the F-type band. The room-temperature-measured intensity of the F-type band is enhanced 2.5 times when irradiations are performed near 80 ^∘{}K. A brief comparison is made with spectra obtained from 3-MeV-proton-bombarded MgO and from fast-neutron-irradiated MgO.