Optical absorption and fluorescent behaviour of selenium in ternary silicate glasses

Abstract

Optical absorption and fluorescent behaviour of selenium in the ternary soda-lime-silica, soda-strontia-silica and soda-baria-silica glasses having molar composition 20Na2O·10RO·70SiO2 (where R = Ca, Sr and Ba) were studied systematically. Selenium in its elemental form was found to produce a variety of pink colour shades in soda-lime-silica and soda-strontia-silica glasses by optical absorption measurements whereas the infrared transmission studies detected the presence of selenium as selenite (SeO32-) and selenate (SeO42-) ions which did not produce any color in glass. The results of optical measurements in the glass containing Se ⇌ SeO32- ⇌ SeO 42- species were discussed in the light of the general principles of spectroscopy. The molar extinction coefficient of selenium was calculated and found to be around 20 and 80 1 · mol-1 · cm-1, respectively, in soda-lime-silica and soda-strontia-silica glasses at their wavelength maxima at around 485 and 500 nm, which dictated the intensity of the broad absorption bands marked due to selenium in the glass. However, the selenium was found to produce a golden yellow color in soda-baria-silica glass. This is due to the shift of the valence state of selenium towards the selenite (SeO32-) and selenate (SeO42-) state with increasing basicity of the glass. The values of the emission cross-section obtained for selenium based on the fluorescence spectral studies showed that the soda-lime-silica glass emitted more intense fluorescence than the rest of the silicate glasses.