EFFECTS OF UV EXPOSURE ON E' CENTERS FORMED IN CRUSHED QUARTZ GRAINS

Electron spin resonance (ESR) study of E' centers in crushed quartz (S iO2) indicated the formation of a new type of E' center by UV-irradiat ion. On the other hand, the concentration of E' centers formed by gamm a-irradiation in the crushed quartz is reduced by UV-irradiation. It w as possible to distinguish between the three types of E' centers in cr ushed quartz (E'(c): formed simply by crushing, E'(UV): formed by crus hing and UV-irradiation and E'(gamma): formed by crushing and gamma-ir radiation) using UV-irradiation. The distribution of the activation en ergy of the E' centers just after crushing was revealed by annealing e xperiments and computer simulation. The technique of characterization by UV-irradiation will be useful for evaluating the local strain in Si O2, especially in natural quartz.