Dislocation mechanism of fading of luminescence intensity

Depth profiles of nanohardness and photoluminescence of $F_2$ and $F_{3}^{+}$ centers in LiF crystals irradiated with 12 МэВ $^{12}$С, 56 МэВ $^{40}$Ar and 34 МэВ $^{84}$Kr ions at fluences $10^{10}$ − 1015 ион/$см^{2}$ have been studied using laser scanning confocal microscopy, dislocation etching and nanoindentation techniques. The depth-resolved nanohardness measurements and dislocation etching data have shown a remarkable hardening effect and increased concentration of dislocations and other nanodefects in the end-of-range region with dominant contribution of defects formed via elastic collision (nuclear loss) mechanism. The observed fading of luminescence intensity at high fluences is related to intense nucleation of dislocations as sinks for aggregate color centers. An activating role of local stress field of dislocations and other extended defects in the evolution of damage structures is suggested.