EPR Study of Radicals Produced by Gamma-Irradiation in Marine Mollusc (Venus Sp.) Fossils

Abstract

In this study, gamma-irradiated marine mollusc (Venus sp.) fossils were investigated by electron paramagnetic resonance (EPR) at ambient temperature. Powder X-ray diffraction technique indicates that the Venus sp. fossils were made mainly of CaCO<inf>3</inf>. Before γ -irradiation, the EPR lines of the powder of fossil samples showed the existence of Mn2+ (I = 5/2, 100% natural abundance) ions with g<inf>av</inf> = 2.0055 and A<inf>av</inf> = 9.4 mT. γ -Irradiation-induced additional defects in Venus sp. fossil were attributed to axial ĊO<inf>3</inf>- (g⊥ = 2.0171, g// = 2.0048), orthorhombic ĊO<inf>2</inf>- (g<inf>x</inf> = 2.0030, g<inf>z</inf> = 2.0018, g<inf>y</inf> = 1.9973, g<inf>av</inf> = 2.0007), freely rotating ĊO<inf>2</inf>- (g<inf>iso</inf> = 2.0007), isotropic ṠO<inf>2</inf>- (g = 2.0057), axial ṠO<inf>3</inf> - (g⊥ = 2.0036, g // = 2.0024) and isotropic ṠO <inf>3</inf>- (g = 2.0032) free radicals. The g-values of these free radicals were compared with the literature data belonging to similar defects.