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Radical species like CO-2,CO-3, SO-2, and SO-3 can be created by exposing natural and synthetic calcium carbonates to sunlight or to the light of a Hg(Xe) lamp. This poses as a risk for ESR dating of these materials, because the radicals formed by light exposure cannot be distinguished from those generated by radioactivity. Furthermore, paramagnetic centers like SO-2, electrons trapped near Zn2+ or Cd2+ ions, surface defects, and radicals with g?=2.0040, can be bleached in ?-irradiated samples by light and show conversion effects.
Radiation defects in alkaline earth silicate glasses are studied by means of ESR and optical spectroscopies. Previously undiscovered relations between findings of both methods are deduced using four different experimental tools: (i) variation of chemical glass composition; (ii) isochronal annealing of ggr-irradiated samples; (iii) optical bleaching of ggr-irradiated samples; (iv) variation of the ggr-dose. Oxygen hole centres are mainly responsible for the radiation induced absorption in the visible part of the optical spectrum. Previously undescribed electron centres with broad and asymmetric ESR resonances (gprime=1·955) contribute to the optical spectra (2002000 nm) in a small way. It is suggested they are electrons trapped on small aggregates of alkaline earth ions. The radiation induced recharging of incorporated Fe3+ ions is also evidenced by optical and ESR spectroscopies. Fe3+ ions react as electron traps forming not only Fe2+ but also {Fe3+}- species which might be responsible for an absorption band at 300 nm. A correlation was found between the changes of intensity with those of the ESR spectroscopically detected Fe3+ content of the samples.