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![[Figure 8]](hi5552fig8mag.jpg)
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Figure 8
(a) Schematic of the mechanism of radioluminescence (RL) in wide-band-gap materials: luminescence results from the recombination of excited electrons and trapped holes. During RL, deep traps become filled with charge: the quantity of these charges can be assessed by probing with a low-energy laser, which gives rise to time-decaying anti-Stokes shifted optically stimulated luminescence, OSL. Since the penetration depth of the RL excitation photons is dependent on energy (inset: data compiled from tables provided by https://cindy.lbl.gov ), tuning this energy allows for the probing and examination of both surface and bulk defects. (b) Dynamics of the RL signal in natural sedimentary quartz, for prolonged RL exposure. If the exposure is halted, the OSL can be used to assess the amount of trapped charge (inset left). Exposing with the laser, however, causes further redistribution of charge in the material; this gives rise to a transient in the RL if this is then continued (inset, right). (c) For the quartz sample studied, the nature of the defects is invariant with depth, as indicated by the independence of the OSL recombination kinetics, after exposure to ionizing radiation of different energies: curve fitting reveals three first-order components, the `fast' and `medium' being dominant; their time constants are plotted here. However, the strong variation in the relative amount of OSL and RL produced, depending on RL stimulation energy, reflects a change in either the defect distributions or in the competition for charge between the defects. |
![[Figure 8]](hi5552fig8.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
