Excimer luminescence of 2,2′-bipyridine in the silica gel glass

Abstract

In this paper, 2,2′-bipyridine molecules are doped into silica gel glass by a sol–gel process. The luminescence properties of 2,2′-bipyridine are studied with the luminescence decay curve and photoluminescence (PL) spectra measured at room temperature and various temperatures. Two broad emission bands at around 400 and 454 nm, respectively, are observed for 2,2′-bipyridine in the no heat treatment silica gel glass. The 454-nm band still shows a broad structureless emission even if measured by a higher resolution measuring system and at lower temperatures, and has the similar temperature dependence of the emission intensity as the observation made by Döller et al., which is an indication that the broad structureless band is an excimer fluorescence of 2,2′-bipyridine. The excimer cannot be formed and the emission disappears after the doped gel glass is heat-treated at 200 °C for 24 h.