Spectroscopic studies on the Eu(BTA) 3·2H 2O complex in situ synthesized in the vinyl modified silicate

Abstract

The possible mechanisms responsible for the electronic transitions and excitation energy migration of the Eu(BTA) 3·2H 2O (BTA = benzoyltrifluoroacetone) complex synthesized in situ in the vinyltriethoxysilane (VTES)-derived ORMOSIL and the effective site symmetry of the Eu 3+ ion in this complex are discussed in comparison to that in ethanol. The measurement of the steady-state photoluminescence (PL) spectrum at 10 K was employed, and the fluorescence decay curves of the Eu(BTA) 3·2H 2O complex synthesized in situ in the ORMOSIL and comparatively the complex polycrystalline powder dissolved in ethanol solution were studied at room temperature. For the Eu(BTA) 3·2H 2O complex synthesized in situ in the ORMOSIL, thermal reactivation probability from the 5 D 0 level to the 5 D 1 level and the non-radiative transition probability from the 5 D 0 level to the 7 F J levels are reduced as a result of a rigid environment around the complex. A relatively shorter lifetime of the 5 D 1 level and larger lifetime of the 5 D 0 level of the Eu 3+ ions than those in the complex dissolved in ethanol are observed, indicating an enhancement of the emission yield from the 5 D 0 level. The number of sublevels and bands induced by Stark splitting of the 7 F J levels of the Eu 3+ ions as a result of the ligand perturbation suggests that the site symmetry of the Eu 3+ ion in the Eu(BTA) 3·2H 2O complex synthesized in situ in the ORMOSIL is C 1 or C 2 or C S.