Interstitial oxygen molecules in amorphous SiO2. II. The influence of common dopants (SiOH, SiF, and SiCl groups) and fictive temperature on the decay of singlet photoluminescence

Abstract

Time decay of photoluminescence due to interstitial oxygen molecules (O2) in synthetic amorphous SiO2(a-SiO2) was studied by varying the fictive temperature and the concentrations of common dopants (SiOH, SiCl, and SiF groups). The decay constant is insensitive to the fictive temperature, but strongly depends on the type of dopants: it is reduced by the nonradiative decay via an energy transfer from O2 to the vibrational modes of the dopants. The increases in the nonradiative decay rate due to SiOH, SiF, and SiCl groups are strong, slight, and negligible, respectively, which correlates with their vibrational energies. The quantum yield decreases by ∼20% as the SiOH content increases from 1017 to 1020cm−3. The deviation from the single exponential decay is due to the shape variation in the a-SiO2 network cages that surround O2, and to the distance distribution between O2 and SiOH groups.

Properties of HO 2 • radicals induced by γ-ray irradiation in silica nanoparticles

“…The proportionality factor between the O 2 concentration and the PL intensity I PL just defined is equal to the ratio between α, a quantity assumed independent of the type of nanoparticle considered [18,19], and the PL lifetimes. Taking advantage of this consideration it is possible to define I PLrevised :…”

“…We can express the factor K i as the ratio between a quantity α (here considered indipendent from the features of the nanoparticles [17][18][19]22]) and the O 2 PL life time τ i :…”

“…In fact, to detect and evaluate the amount of interstitial O 2 one can make use of the electronic transition in O 2 from the first excited state 1 Δ g to the ground state 3 Σ g − . This transition gives rise to an infrared (IR) photoluminescence (PL) band at~1272 nm that a Raman spectrometer equipped with a Nd:YAG laser source at 1064 nm can detect [8,[16][17][18][19][20].…”

Near infrared radio-luminescence of O2 loaded radiation hardened silica optical fibers: A candidate dosimeter for harsh environments

“…7 The infrared photoluminescence of O 2 enclosed in silica was investigated by several authors. [8][9][10] The interstitial molecular oxygen exhibits an emission band centered at 1272 nm (0.975 eV), excitable in the visible and NIR, arising from its first excited singlet state, with a Full Width at Half Maximum (FWHM) of $16 nm (0.011 eV) and decay time as long as $0.8 seconds for silica glasses with low-OH content. 9 The same NIR emission was also detected in silica optical fibers exposed to fission reactor radiation conditions, where both neutrons and c-rays are present.…”

“…[8][9][10] The interstitial molecular oxygen exhibits an emission band centered at 1272 nm (0.975 eV), excitable in the visible and NIR, arising from its first excited singlet state, with a Full Width at Half Maximum (FWHM) of $16 nm (0.011 eV) and decay time as long as $0.8 seconds for silica glasses with low-OH content. 9 The same NIR emission was also detected in silica optical fibers exposed to fission reactor radiation conditions, where both neutrons and c-rays are present. 11,12 Therefore, such OFs must have contained a certain amount of O 2 , either generated by the irradiation or left over from the production process of the OFs.…”