Abstract

The kinetics of fractoluminescence of quartz single crystals subjected to an impact with a steel striker is investigated. It is established that, within several tens of microseconds after an impact, there appear two to three tens of fractoluminescence flashes. An analysis of the luminescence spectra demonstrates that fractoluminescence arises upon the transition from an excited electron level to the ground electron level in SiO. radicals formed as a result of the breaking of the Si-O-Si bonds. Acoustic emission signals are detected simultaneously with fractoluminescence. It is revealed that all except the first of the fractoluminescence flashes arise from vibrations of the crystal-striker system after the impact. Approximately ten cracks with linear sizes of several millimeters are observed on the surface of the plate. The SiO· radicals are assumed to be located at the surface of these cracks. The time of fractoluminescence excitation is determined by the growth rate of cracks and amounts to ≈1–3 μs. After the growth of the cracks is terminated, the fractoluminescence intensity decreases exponentially with a mean time of ≈12 μs, which does not depend on the temperature. This makes it possible to attribute the observed luminescence to fluorescence, i.e., to a singlet-singlet transition.

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