Blue And Red Thermoluminescence Of Natural Quartz In The Temperature Region From-196 To 400 Degrees C

Quartz samples of three different origins were gamma-irradiated with 20 kGy at room temperature or at the temperature of liquid nitrogen (- 196 degrees C), and analyzed by on-line TL-emission spectrometry over two temperature ranges: above 200 degrees C (high-temperature region) and - 196 to 200 degrees C (low-temperature region). The emission spectra in the high-temperature region could be separated into intense blue TL (BTL) or red TL (RTL) properties. All quartz samples displayed more or less both properties of BTL and RTL in the low temperature region, shifting the BTL-emission spectra towards violet. Particularly, volcanically originated quartz (RTL, Medeshima) showed highly complex BTL and RTL peaks in the low-temperature region, and a stronger simple RTL peak in the high temperature. These complex glow-curve peaks are considered to reflect the presence of many crystal defects and much content of impurities in the volcanically formed quartz. In the glow-curve measurements, Brazilian quartz (quartz-vein origin) gave weak RTL and intense BTL in the low-temperature range, followed by faint emission of BTL in the hightemperature side. On the other hand, the radiation-induced colored (CC) part of a Madagascan crystal rock slice (hydrothermal origin) showed intense BTL together with slight RTL in the low temperatures, followed by strong BTL and appreciable strength of RTL in the high temperatures.The BTL-emission pattern (TL-color image) of a Madagascan slice showed a complementary relationship between irradiations at liquid-nitrogen temperature and at room temperature. To explain these radiation-induced phenomena from quartz, hydrogen radicals and Li+ ions, derived from radiolysis products of OH-related impurities, could operate to eliminate the BTL centers by recombination below the room temperature. (c) 2007 Elsevier Ltd. All rights reserved.