Fluorescence spectra and lifetime measurements of a formato complex of europium(III) in HCOOH-HCOONa buffer solution

Abstract

The photophysical properties of the Eu 3+ ion in HCOOH-HCOONa buffer solution were studied. The high resolution emission spectrum is consistent with the presence of only one Eu 3+ containing species of C 2 v symmetry. The emission quantum yield in D 2O solution is 0.17 upon excitation at 394 nm in the 5L 6 absorption band. Luminescence decay measurements in H 2O (τ = 140 ns) and D 2O (τ = 2.50 ms) solutions show that the formato complex contains seven water molecules in the first coordination sphere. The most likely formulation of the formato complex ion in solution is Eu(HCOO) 2(H 2O) 7 +, where the formate ion plays the role of a monodentate ligand.