Fluorescence MDR features of Eu3+ doped sol–gel TiO2 hydrate microspheres

Single particle fluorescence of Eu3+-doped TiO2 hydrate microsphere formed in sol–gel process has been studied, where TiO2 hydrate spheres are characterized by the relatively high refractive index of 1.8. Observed fluorescence spectra display a structure that consists of narrow peaks of varying height superimposed on the familiar broadband emission from europium ions. Such emission peaks result from spherical cavity resonances, and resonance mode positions were assigned from Lorenz–Mie theory calculation. We have also directly measured the lifetime of the MDR peaks of the fluorescence spectra from 8-μm diameter Eu3+ doped TiO2 hydrate microsphere.