UV laser-induced enhancement of photoluminescence intensity in vitrified terbium(III) β-diketonate complex film in air

We report on a novel 5 mu m thick vitrified film prepared from the amorphous powder of the mesogenic terbium (III) beta-diketonate complex and supported on a quartz plate through melt-processing technique. For the first time a 16-fold increase in the mean photoluminescence intensity of Tb3+ ions in the film was observed after a prolonged irradiation of the film by 337 nm pulsed nitrogen laser in air at room temperature. The analysis of optical spectroscopy data has shown that the main reason responsible for the observed phenomenon was a change in the inner coordination spheres of Tb3+ ions. It resulted in an increase in energy gaps between the emitting D-5(4) level of the Tb3+ ions and triplet states of ligands. In this way the efficiency of the energy back transfer from the D-5(4) level of the Tb3+ ions to the triplet state of the ligands was decreased and the mean photoluminescence intensity of the Tb3+ ions in the film was enhanced.