Mechanoluminescence by impulsive deformation of γ-irradiated Er-doped CaF2 crystals

An impulsive technique has been used for mechanoluminescence (ML) measurements in γ-irradiated Er doped CaF2 crystals. When the ML is excited impulsively by the impact of moving piston on to γ-irradiated CaF2:Er crystals, two peaks are observed in ML intensity with time and it is seen that the peak intensities of first and second peaks (Im1 and Im2) increase with increasing impact velocity. However the time corresponding to first and second peaks (tm1 and tm2) shifts towards shorter time values with increasing impact velocity. It is also seen that the total ML intensity ITotal initially increases with the impact velocity and then it attains a saturation value for higher values of the impact velocity. We have presented a theoretical explanation for the observed results.