Luminescence lifetime of lanthanide(III) ions in aqueous solution containing azide ion

Abstract

Luminescent lanthanide ions have been studied using Time-Resolved Laser-induced Luminescence Spectroscopy. The luminescence lifetimes, τ, of excited states of several trivalent lanthanide (Ln 3+) ions (Ln=Nd, Sm, Eu, Gd, Tb and Dy) in aqueous solution, containing azide ion (N 3 −), have been measured to evaluate the quenching effect of N 3 −. The luminescence decay constants k obs of Ln 3+ (Ln=Nd, Sm, Eu, Gd, Tb and Dy) were measured in H 2O solution, and in the case of Eu 3+ also in D 2O solution. The calculated values of the decay constants indicate that, under the conditions of this work, N 3 − strongly quenches the excited states of Gd 3+, Eu 3+ and Tb 3+. The order of the energy gap, Δ E, between the emitting and the ground state of the Ln 3+ ion is Gd>Tb>Eu, while that of the quenching rate constants by azide, k N3, show the following order: Gd>Eu>Tb. In the case of Nd 3+, Sm 3+ and Dy 3+ no quenching effect was observed.