Sputtering and coloration process in LiF thin layers induced by MeV ion bombardment

Beams of 2.0 MeV nitrogen ions, produced by a Van de Graaff generator, were used in order to create point defects in polycrystalline LiF thin films. The radiation effects were examined by optical absorption, RBS, PDMS and XPS methods. The concentration of the produced F-centers exhibits a saturation behavior, but decreases for doses higher than ∼ 1 × 10 16 cm −2 . A fluorine sputtering yield Y ∼ 3 was determined by using RBS. Moreover, XPS and PDMS techniques detected surface Li enrichment as a result of the ion bombardment. All these results denote the relevance of the sputtering in the de-coloration process of LiF thin layers.