Scanning Microscopy


The first part of this paper reviews the observation of the unconventional thermoluminescence {TL(M), where M = Li or Na} peaks observed in the glow curve of Li-and Na-containing quartz, and describes the full solution of the puzzling effect of the TL(M) peaks which needed a two irradiation procedure for their formation. Of interest is the intermediate warming (IW) method, which consisted of two irradiations and warming of the sample to 150-300 K between the two irradiations. This was explained as follows: the first low temperature irradiation produces {AlO4/M/h}+ centers, when the now loosely bound M ions will be released from the Al-sites by warming to, let us say, 250 K. This model differs from the one accepted in literature according to which irradiation at above 200 K releases the M ions from the {AlO4/M}0 centers.

The second part describes some characteristics of the {SiO4/M}0 centers which were found to be related to the TL(M) peaks. These include the dose dependence of these peaks, which was found to be affected strongly by competing electron traps, and the possibility to excite the TL(M) by a single irradiation. The single irradiation excitation provided a simple measurement of the binding energies of the M ions to the {AlO4/M/h}+ centers. These were found to be 0.25 eV and 0.31 eV for Li and Na, respectively.

Differences in the TL(M) intensities obtained by first irradiation at 250 K and second at low temperature and those obtained by the IW method were also investigated. Finally, the 3.2 eV X-ray induced luminescence is shown to be closely related to the TL(M) peaks.

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