Optically induced dichroism of Z2-centers in LiF : Mg, Ti (TLD-100)

Crystals of γ-irradiated TLD-100 are bleached at 313 nm at 77 K with light polarized in one selected direction, and then with light polarized at 900 from the initial direction. Dichroism is induced in the Z2 center by bleaching with polarized light. The decrease in absorbance is always larger when measured with light polarized in the same direction as the bleaching light. There is an increase in absorbance at 313 nm after the second bleach when the measuring light is polarized perpendicular to the bleaching light. The results are observed in all four directions: [001], [010], [011], and [011]. A second defect center, which adsorbs at 313 nm, is proposed to explain the observed dichroism. (author)