The role of silver in the radiophotoluminescent properties in silver-activated phosphate glass and sodium chloride crystal

Abstract

We have systematically investigated the X-ray-induced radiophotoluminescence (RPL) bands in a silver-activated phosphate glass (PG:Ag), and we have ascribed these bands to Ag 0 , Ag 2+and Ag 2 + centres, using optical characterisation such as absorption, excitation, emission and lifetime measurements. The absorption spectrum of PG:Ag irradiated with X-rays was decomposed into six Gaussian bands on the basis of its strong analogy with irradiated silver-activated sodium chloride (NaCl:Ag). We confirmed that blue emission peaking at 450 nm was connected with the 270 and 345 nm bands of the excitation spectrum, while orange emission peaking at 560 nm was associated with the 308 nm excitation band. Each band of the excitation spectrum was in turn attributed to an Ag 2 + , Ag 0 or Ag 2+ centre by analogy with the RPL of NaCl:Ag. The excited-state lifetimes for each emissive process were also determined for different X-ray doses. In conclusion, we determined that both blue and orange emissions result from radiation-induced (rather than intrinsic) properties in the range of 1.22 -24.5 Gy.

Formation and assignment of silver defect centres in phosphate glass induced by femtosecond laser pulses

“…The former corresponds to the decomposed 307 nm Gaussian band, while the latter corresponds to the decomposed 270 and 354 nm bands, respectively. The blue emission with some portion of the orange emission are strongly related to the 270 and 345 nm excitation bands, which is completely analogous to the blue emission of NaCl:Ag associated with bands "B" and "C" (Kurobori et al, 2010), respectively.…”

“…The absorption spectrum is obviously due to the superposition of a number of individual absorption bands corresponding to the different colour centres. Therefore, the peak fitting analysis was carried out on the basis of the strong analogy with X-ray-irradiated silver-doped sodium chloride (NaCl:Ag) (Kurobori et al, 2010). The absorption spectrum could be decomposed into the sum of separate Gaussian bands (indicated by a dashed line) from "A" to "F", peaking at 225, 252, 270, 307, 354 and 424 nm, respectively.…”

“…Recently, we have systematically investigated the assignments and optical properties of X-ray-induced silver-related species of PG:Ag by means of various optical measurements such as RPL decay curve analysis, peak fitting analysis and heat treatments (Kurobori et al, 2010;Zheng and Kurobori, 2011). It was established from these results that the decomposed six Gaussian bands induced by X-ray irradiation in PG:Ag were, in turn, attributed to Ag + , Ag 3 + or Ag 3 2+ , Ag 2 + , Ag 2+ , Ag 0 and hole-trap centres, respectively.…”

A three-dimensional imaging detector based on nano-scale silver-related defects in X- and gamma-ray-irradiated glasses

“…Typical excitation spectra consist of two different bands. One spectrum peaks at 310 nm for an emission at 560 nm attributed to the hole-trapped Ag 2+ centres, and the other peaks at 270 and 340 nm for an emission at 460 nm attributed to the Ag2 + (reaction: Ag + + Ag 0 → Ag2 + ) and electron-trapped Ag 0 centres, 13,14) respectively. Moreover, the corresponding RPL spectra excited by the commercially available laser lines, indicated by arrows, at 337 nm (a pulsed N2 laser), 349 nm (a Q-switched Nd:YLF laser), 375 nm (a cw laser diode) and 405 nm (a cw laser diode), as well as at a 310 nm peak of the excitation spectra for an X-ray irradiated sample, are also shown.…”

“…The reasons are as follows: the decay time of the blue RPL is much shorter than that of the orange RPL. 13) The Ag 0 and Ag 2+ CCs emitting the blue and orange RPL in Ag-activated phosphate glass will never disappear unless the glasses are annealed at a high temperature of about 400 °C. 15) Therefore, under the steady-state time scale the integrated orange RPL intensity with the long decay lifetime is enhanced in comparison with the integrated blue RPL intensity with the short decay lifetime.…”