INTRINSIC AND IMPURITY-RELATED POINT-DEFECTS IN AMORPHOUS SILICA - A SPECTROSCOPIC STUDY

Absorption, photoluminescence emission, and excitation measurements of “as grown” and neutron irradiated amorphous silica characterized by different impurity and OH content, confirm the composite nature of the ≈ 5.1 eV (B2) absorption band and make it possible to distinguish between structural defects and impurity‐related centers. A detailed analysis of the published results on the subject shows that none of the up to date existing models fully accounts for the complex of the experimental observations. A new scheme is proposed in which all the available data find a consistent collocation. It is suggested that two structurally different centers, with optical absorptions in the B2 region, can be simultaneously present in amorphous SiO2; they exist in two variants: bare defect (also produced by neutron irradiation) or impurity‐perturbed center. Some proposals for a deeper understanding of absorption and photoluminescence in glassy SiO2 are finally advanced. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA