Key points are not available for this paper at this time.
Radiation-induced changes in high-purity fused silica during prolonged irradiation with a pulsed laser at 193 nm have been studied. Radiolytically induced UV absorption bands, an increase in index of refraction, and stress birefringence are observed. The formation mechanisms are analyzed in terms of radiolytic atomic rearrangement of a-SiO2 initiated by two-photon absorption. The quantum efficiency for the formation of E′ point defects per pair of absorbed 193 nm photons has been determined to be ∼7.5×10−4; matrix compaction, as high as a few parts in 10−5, is identified as the source of the birefringence and index change. It has been further observed that E′ centers can be photobleached.
Rothschild et al. (Mon,) studied this question.