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

The possible mechanisms responsible for the electronic transitions and exci tation energy migration of the Eu(BTA)(3).2H(2)O (BTA = benzoyltrifluoroace tone) complex synthesized in situ in the vinyltriethoxysilane (VTES)-derive d ORMOSIL and the effective site symmetry of the Eu3+ ion in this complex a re discussed in comparison to that in ethanol. The measurement of the stead y-state photoluminescence (PL) spectrum at 10 K was employed, and the fluor escence decay curves of the Eu(BTA)(3).2H(2)O complex synthesized in situ i n the ORMOSIL and comparatively the complex polycrystalline powder dissolve d in ethanol solution were studied at room temperature. For the Eu(BTA), 2H 20 complex synthesized in situ in the ORMOSIL, thermal reactivation probabi lity from the 5D(0) level to the 5D(1) level and the non-radiative transiti on probability from the D-5(0) level to the F-7(J) levels are reduced as a result of a rigid environment around the complex. A relatively shorter life time of the 5D1 level and larger lifetime of the D-5(0) level of the Eu3+ i ons than those in the complex dissolved in ethanol are observed, indicating an enhancement of the emission yield from the D-5(0) level. The number of sublevels and bands induced by Stark splitting of the 7FJ levels of the Eu3 + ions as a result of the ligand perturbation suggests that the site symmet ry of the Eu3+ ion in the Eu(BTA)(3).2H(2)O complex synthesized in situ in the ORMOSIL is C-1 or C-2 or C-S. (C) 2001 Elsevier Science B.V. All rights reserved.