Changes in luminescent properties of vitrified films of terbium(III) β-diketonate complex upon UV laser irradiation

Structural modifications following long-term UV irradiation with a pulsed nitrogen laser led to a decrease/increase in the luminescence intensities of vitrified films with the thickness of 8/20 µm, respectively. The films were prepared from a terbium(III) β-diketonate complex. Optical spectroscopic studies revealed that these features are associated with different structures of the films. The 20 µm film includes the aggregates hindering the non-radiative relaxation of the T1 states of ligands. Such a phenomenon is not observed in the 8 µm film. A comparative analysis of the luminescent data indicates that the redistribution of the T1 energies of the ligands under UV modification is the predominant reason for the changes of the luminescent properties of the films.