F<sub>2</sub> excimer-laser irradiation induces two major changes in SiO<sub>2</sub>: OH glass impregnated with H<sub>2</sub> molecules. First, the vacuum–UV optical absorption edge is bleached, and the absorption at 157 nm decreases from 0.95 to 0.68 cm<sup>-1</sup> . Second, preexisting free SiOH groups and interstitial H<sub>2</sub> are photochemically converted to hydrogen-bonded hydroxyl groups. It is suggested that the bleaching of the UV-absorption edge is caused by a change of OH groups from a free to a hydrogen-bonded state and by photolysis of distorted Si—O bonds that are absorbing in the edge region.
© 1999 Optical Society of America
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.2180) Lasers and laser optics : Excimer lasers
(140.3330) Lasers and laser optics : Laser damage
(160.6030) Materials : Silica
Masafumi Mizuguchi, Linards Skuja, *Hideo Hosono, and Tohru Ogawa, "Photochemical processes induced by 157-nm light in H2-impregnated glassy SiO2:OH," Opt. Lett. 24, 863-865 (1999)