Optical investigation of metallic colloids in ion-irradiated lithium fluoride (LiF) crystals

The measured room-temperature absorption spectra of LiF crystals implanted with 1.5 MeV He+ ions at different ion doses are presented. The application of a theoretical model allowed us to give an estimation of the band intensities associated with various kinds of electronic defects and to study their dependence on the ion dose. The model also considers the contribution due to narrometric lithium colloids, whose formation starts in the dose range at which the production of colour centres saturates.