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Optical and AFM analysis of defect induced in lithium fluoride by energetic lead ions

H.Benhacine, A.Meftah, M.Izerrouken, S.Kadid

Single crystal samples of lithium fluoride irradiated at normal incidence with swift heavy ion Pb+52 of energy between 140 and 840 MeV in the fluence range 1x109 - 4x1012 ions/cm2 are characterized by optical measurements (absorption and photoluminescence) and Atomic Force Microscopy (AFM).Opticalmeasurements showthat F center concentration increases with increasing fluence and reaches saturation at higher fluences. On the other hand, F center aggregates F2 and  3 F increase linearly in the same fluence range. The track radius deduced, using a model of saturated track, increases linearlywith electronic stopping power. It extends from9 to 22 nmwhenmean energy loss respectively varies from11 to 25eV/nm. The ion induced damage on the surface is observed by AFM under ambient conditions.AFMreveals circular damage zones, consisting of small hillocks. The mean diameter of the track cross sections depends on electronic stopping power  e dE dx and variesfrom 9 to16 nm and with heights of a few nanometers.