2 research outputs found
Stability of E' centers induced by 4.7eV laser radiation in SiO2
The kinetics of E' centers (silicon dangling bonds) induced by 4.7eV pulsed
laser irradiation in dry fused silica was investigated by in situ optical
absorption spectroscopy. The stability of the defects, conditioned by reaction
with mobile hydrogen of radiolytic origin, is discussed and compared to results
of similar experiments performed on wet fused silica. A portion of E' and
hydrogen are most likely generated by laser-induced breaking of Si-H
precursors, while an additional fraction of the paramagnetic centers arise from
another formation mechanism. Both typologies of E' participate to the reaction
with H_2 leading to the post-irradiation decay of the defects. This annealing
process is slowed down on decreasing temperature and is frozen at T=200K,
consistently with the diffusion properties of H_2 in silica.Comment: 12 pages, 3 figures, in press on J. Non cryst. solids (2007