Potochemistry of NaI Doped Sodiumsilicate Glasses

Abstract

There have been very extensive studies on the photochemistry of transition elements in various glasses by many authors, but very few, of non-metallic anions dissolved in glasses. Therefore, the photochemistry of NaI containing sodiumsilicate glasses was investigated by the writers. The reason the writers took NaI as the reagent was that the photochemistry of iodine in some solvents and it's electronic state had been fairly well known. The samples used in this study are shown in Table 1. The increases of absorption spectra after X-and UV irradiation, photo and thermal fading of their induced absorption were studied.The increases of optical absorption in UV or X-ray irradiated glasses are shown in Fig. 1 and 2. Fig. 3 shows, how the induced absorption in the same glass after UV irradiation is affected by water.Photo and thermal fading of these induced absorption bands are shown in Fig. 4-8.As the result of examining of such absorption changes, it became clear that the induced absorption bands after X-or UV irradiation were 250-270mμ, 290mμ, 350mμ, 380mμ, and 715mμ and in the case of dilute NaI containing glasses, moreover some weakend color centers of sodium silicate glasses in itself were overlapped on these induced bands, namely, iodine ion has a suppression effect on the growth of glass color centers by X-ray or UV irradiation.Conversely 570mμ band (electron trapping center in reduced Na2O-3SiO2 glass) was strengthened by photochemistry of NaT as shown in Fig. 12, but was very unstable.Considering on the above results, the photochemistry of NaI containing glass is the photo-oxidation of I- in the glass.Assignments of induced bands after the irradiation are as follows; 250-270mμ band depends on a electron trapping center in glass matrix, 290, 350mμ and 380, 715mμ depend upon I3- and I2- respectively.The more basic is the glass, the absorptions of I3- and I2- are the more unstable, and moreover they causes thermal fading at the lower temperature.