Photochromic Behavior in the Fluorescence Spectra of 9-Anthrol Encapsulated in Si−Al Glasses Prepared by the Sol−Gel Method

Abstract

The fluorescence spectra of 9-anthrol during the sol−gel−xerogel transitions of 13 systems containing different silicon and aluminum ratios and catalysts have been observed at a constant temperature (300 K) as a function of the sol−gel reaction time. Fluorescence decay curves for typical xerogel samples also have been observed. 9-Anthrol in the sol−gel systems showed four different fluorescence bands originating from the hydrogen-bonded, the complex, the ion pair, and the anion form species. Continuous light irradiation of the xerogels at 360 nm led to an increase in the fluorescence at 480 nm. These findings indicate that anthrone transforms to 9-anthrol by the photoinduced intermolecular proton transfer in these matrixes. The most effective and remarkable tautomerization occurred in the Si:Al = 90:10 system, and it was concluded that this photochromic behavior occurs by the photoinduced proton transfer from a proton at the surface Brønsted acid site on the −O−Si−O−Al−O− network to the anthrone molecule.

Luminescence properties of a Tb3+ activated long-afterglow phosphor

“…Two decay parameters, 1 = 4.63 × 10 −4 s and host. This double-exponential decay behavior is frequently observed when the excitation energy is transferred from the donor [14,15]. An important result of the present work is that we have observed intense green-light-emitting long-afterglow in these CaZnGe 2 O 6 :Tb 3+ system.…”

Synthesis and characterization of spherical Sr2CeO4 phosphors by spray pyrolysis for field emission displays

“…The double-exponential decay behavior of the as-prepared Sr 2 CeO 4 particles is consistent with the existence of two different charge-transfer transitions in Sr 2 CeO 4 [5]. The average lifetime for the Sr 2 CeO 4 particles, defined as t ¼ 18], is determined to be 37.4 ms, which is of the same order of magnitude as reported in Ref. [8].…”

Luminescence properties of Eu2+ and Eu3+ doped calcium-deficient hydroxyapatite prepared in air

“…This indicates a possible site-tosite energy transfer. Non-exponential decay curve usually indicated energy transfer from a donor to an acceptor [24]. For example, in the Eu 3+ -doped strontium fluoroapatites, the Eu 3+ predominantly occupied Sr-II site (C S symmetry) and the intense resonant energy transfer from Eu 3+ (Sr-I) to Eu 3+ (Sr-II) made the emission from Sr-I site very weak [25].…”