The effects of radiation on the near infra-red absorption spectrum of α-quartz

Abstract

The variation of the absorption strength and spectrum in the region of 3 μ has been determined for different specimens of crystalline quartz and for x-ray, electron and pile irradiated crystals. It is shown that the 3 μ group of bands is associated with imperfections rather than harmonics or combinations of lattice vibration frequencies, and that the imperfections are not Frenkel or Schottky defects. Two of the bands, 2·88 and 2·95 μ, are anisotropic, having anisotropic absorption ratios (E_∥c/E_⊥C)≤0·130 and ≤0·145 respectively. A band is induced by pile irradiation at 2·79 μ but tends to saturate at a low dose (< 10¹⁹n^® cm^×2). The band is not produced by ionizing radiation. It is suggested that the 2·79 μ band may be due to 0-H bond formation by association of hydrogen impurity with the products of atomic damage. This band is also anisotropic with a ratio of 0·71. Possible defect axis directions which could give the observed anisotropic ratios are discussed.