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RESEARCH PRODUCT

UV cathodoluminescence of crystalline α-quartz at low temperatures

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description

Two luminescence bands in the UV range were detected in crystalline a-quartzunder electron beam excitation (6 kV, 3–5mA). One band is situated at 5 eV and could be observed in pure samples. Its intensity increases with cooling below 100 K and undergoes saturation below 40 K alongside a slow growth with the time of irradiation at 9 K. The decay curve of the band at 5 eV contains two components, a fast (o10 ns) and a slow one in the range of 200ms. The photoluminescence band at 5 eV with a similar temperature dependence was found in previously neutron-irradiated crystalline a-quartz. Therefore, the band at 5 eV was attributed to host material defects in both irradiation cases. The creation mechanism of such defects by electrons, the energy of which is lower than the threshold for a knock-out mechanism of defect creation, is discussed. Another band at 6 eV, containing subbands in different samples, appears in the samples containing aluminum, lithium and sodium ions. This luminescence is ascribed to a tunnel radiative transition in an association of (alkali atom) 0 -[AlO4] + that is formed after the trapping of an electron and a hole by Li + (or Na + ) and AlO4.