New insights into UV laser irradiation effect on luminescent behavior of vitrified films based on mesogenic lanthanide(III) β-diketonate complexes

Abstract

We revealed the effect of the prolonged UV laser irradiation on luminescent behavior of photonic materials based on mesogenic lanthanide(III) β-diketonate complexes by using a novel 3 μm vitrified film of an europium(III) β-diketonate complex. We used the Eu3+ ions to monitor the UV laser-induced photophysical processes in the film. Despite the fact that usually prolonged UV irradiation leads to irreversible photofragmentation of ligands, we had observed no photodecomposition of the complexes after the irradiation of the film with the 337 nm laser for 5 h. The spectroscopic study revealed (i) a 16.5-fold luminescence intensity decrease due to laser-induced changes in inner coordination spheres of the Eu3+ ions and (ii) the main channel of non-radiative energy losses from the Eu3+ ions through the multiphonon relaxation. These features open up new possibilities for designing advanced photonics materials with excellent photostability and luminescent properties controlled during operation.