| Research Abstract |
Red thermoluminscence from natural quartz grains, which has been initially found in the present laboratory., has been searched from aspects of causes as well as development of conventional 2-dimensional observation for a variety of radiation-induced luminescence, including optically stimulated luminescence (OSL). In addition to these, the luminescence dating and the availability of luminescence onto paleotemperature estimation of some kilns have been studied.
Japanese twin slices and quartz Z-cut ones, which were prepared from a madagascar crystal rock, were observed with color center images (CCI) and thermoluminescence color imaging (TLCI) after X (or gamma) -ray irradiation. It was found that these striped radiation-induced patterns offered an apparently inverse correlation with Al-impurity distribution from an electron probe micro-analyzer (EPMA). On the basis of these striped patterns, some segments obtained from the slice were subjected to more quantitative measurements of TL and C
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CI spectometry, together with the analysis of the concentrations of two kinds of impurity : Al- and OH-impurities. These were analyzed by means of neutron activation analysis and infra-red spectroscopy, respectively. A reverse-correlation was found between the radiation-induced phenomena and the Al- and OH- (probably due to dangling bonds) impurity concentrations, whereas Al-centers from ESR-specta give a positive correlation with radiation-induced phenomena, as is well known. From these experimental results, a model has been proposed in which the H^0-atoms, formed as a radiolysis product from OH impurities, will be able to operate as killers of radiation-induced phenomena.
This model was in consistent with the following results ; the existence of H^0 radicals and intense Al-centers were detected in ESR spectra after the irradiation and subsequent measurements at liquid N_2, whereas the elimination of the Al-center signal, associated with the complete disappearance of the H^0 centers, was confirmed from ESR-measurements on re-cooled samples, after warming once to room temperature. The parts possessing less radiation-induced phenomena were interestingly changed into intense red-TL sites from original blue-TL ones after the annealing treatment, presumably owing to the exclusion of OH impurities as water vapor. Less
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