Post UV irradiation annealing of E′ centers in silica controlled by H2 diffusion

Cannas, Marco; Costa, Sı́lvia M. B.; Boscaino, R.; Gelardi, F. M.

doi:10.1016/j.jnoncrysol.2004.03.111

Cited by 19 publications

(39 citation statements)

References 29 publications

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“…Consistently, in natural silica also the E' centers repeat the same annealing kinetics many times after each high dose re-irradiation [14]. The combination of the two results suggests that in a long exposure the concentrations of E', H(II) and hydrogen reach some equilibrium values regardless of the previous history of the sample, so leading to repeatability of the post-irradiation kinetics.…”

supporting

confidence: 64%

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H(II) Centers in natural silica under repeated UV laser irradiations

Messina

Cannas

Boscaino

2005

Journal of Non-Crystalline Solids

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Abstract:We investigated the kinetics of H(II) centers (=Ge • -H) in natural silica under repeated 266nm UV irradiations performed by a Nd:YAG pulsed laser. UV photons temporarily destroy these paramagnetic defects, their reduction being complete within 250 pulses. After re-irradiation, H(II) centers grow again, and the observed recovery kinetics depends on the irradiation dose; multiple 2000 pulses re-irradiations induce the same post-irradiation kinetics of H(II) centers after each exposure cycle. The analysis of these effects allows us to achieve a deeper understanding of the dynamics of the centers during and after laser irradiation.

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confidence: 64%

“…Apart from =Ge •• , we recall the fundamental role played by the E' centers. In fact, the atomic hydrogen needed to form H(II) center by reaction (1) is made available by the breaking of H 2 at E' centers [8,14]:…”

mentioning

confidence: 99%

H(II) Centers in natural silica under repeated UV laser irradiations

Messina

Cannas

Boscaino

2005

Journal of Non-Crystalline Solids

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“…Several studies have pointed out that the generation of E' center upon laser exposure is associated with the transformation of native precursor center via different mechanisms controlled by one-or two-photons absorption [5][6][7][8][9]. On the other side, in a recent work based on room temperature isothermal annealing experiments, we evidenced that a fraction of photoinduced E' centers in natural silica are passivated in the post irradiation stage through diffusion-limited reactions with molecular hydrogen H 2 [10].…”

Section: Introductionmentioning

confidence: 58%

“…The validity of this model has been recently proved by isothermal annealing OA and ESR experiments performed on UV-irradiated natural silica, in which one observes that the E' center passivation is the main channel reducing the hydrogen content [10,18]. Then, the total and hydrogen are produced approximately in the same amount.…”

Section: Discussionmentioning

confidence: 88%

Nd:YAG laser induced E′ centers probed by in situ absorption measurements

Cannas

Messina

2005

Journal of Non-Crystalline Solids

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We investigated various types of commercial silica irradiated with a pulsed Nd:YAG laser radiation (4.66 eV), with exposure time ranging up to 10000 s. Transient E' centers were probed in situ by measuring the amplitude of the optical absorption band at 5.8 eV (due to E' centers) both during and after irradiation. The laser-induced absorption is observed only in natural samples, whereas the synthetic materials exhibit high toughness to radiation effect. The reported results evidence that the kinetics of E' centers is influenced by their reaction with diffusing molecular hydrogen H 2 made available by dimerization of radiolytic H 0 .

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“…24 Hydrogen is of photolytic origin, produced from Si-H or O-H groups and subsequent dimerization. 25 The attribution of the post-irradiation kinetics of E' and H(II) to diffusion and reaction of H 2 was made on the basis of a semi-quantitative comparison of the typical time scale of the processes with the diffusion parameters of the mobile specie.…”

Section: Introductionmentioning

confidence: 99%