Thermoluminescent properties of mica

Natural as well as β-induced thermoluminescence (TL) of mica of the muscovite type KAl₂(AlSi₃O₁₀)(OH)₂ was investigated. Two main glow peaks were found, as about 150° and 260°C. The 260°C peak is the prominent one in the natural TL curve while the 150°C peak is dominant in the laboratory induced TL. Both curves could be interpreted in terms of two traps with activation energies of 0.75 and 0.97 eV, which are exhausted through a second order process. u.v. phototransfer experiments indicated the existence of additional, deeper traps, undetectable by the regular TL measurements. Dose dependence studies showed a slightly superlinear behaviour. Possible applications to dating in archeology are discussed.