The defects which were created by the 20keV ion bombardment of crystalline samples were investigated by performing optical absorption and luminescence measurements, and F-center band and F-center aggregate bands were identified in crystals after Ar ion bombardment. It was found that the F-center concentration was proportional to the square root of the ion dose. A modified recombination model for interstitials and vacancies was used to explain this dependence. By using photoluminescence techniques, the presence of F3+ centers in both samples was easily detected.

Q.Yan, A.V.Barnes, B.Barnes, N.Seifert, R.Albridge, N.Tolk: Nuclear Instruments and Methods in Physics Research B, 1996, 115[1-4], 415-20