γ-radiation effects on colourless silicates of beryl

gamma-Ray radiation effects on thermoluminescence (TL), electron spin resonance (ESR) and optical absorption (OA) properties of natural uncoloured beryl (Be3Al2Si6O18) were investigated. All the TL glow curves for annealed and subsequently irradiated samples showed a single peak at 165 degreesC. This TL peak did not indicate any relation with the H-0 center, contrary to the TL process proposed for beryl. Irradiation with 10(6) Gy plainly enhanced the following in the samples: the so-called "Maxixe" bands at 600-700 nm due to CO (3) over bar; an OA band at 315-326 nm which can be assigned to ultraviolet charge transfer (UVCT) from O2- to Fe3+ in the tetrahedral Be2+ site, and an ESR signal of Fe 3 observed at g = 4.257. An isochronal thermal anneal study indicated a certain correlation between the OA band at 315-326 nm and the ESR signal of Fe3+. The UVCT process of this OA band is related to Fe3+, and hence the observed correlation is considered to be reasonable. (C) 2002 Elsevier Science B.V. All rights reserved.