Quenching of the Eu3+ Luminescence by Cu2+ Ions in the Nanosized Hydroxyapatite Designed for Future Bio-Detection

The hydroxyapatite nanopowders of the Eu3+-doped, Cu2+-doped, and Eu3+/Cu2+-co-doped Ca10(PO4)6(OH)2 were prepared by a microwave-assisted hydrothermal method. The structural and morphological properties of the products were investigated by X-ray powder diffraction (XRD), transmission electron microscopy techniques (TEM), and infrared spectroscopy (FT-IR). The average crystal size and the unit cell parameters were calculated by a Rietveld refinement tool. The absorption, emission excitation, emission, and luminescence decay time were recorded and studied in detail. The 5D0 → 7F2 transition is the most intense transition. The Eu3+ ions occupied two independent crystallographic sites in these materials exhibited in emission spectra: one Ca(1) site with C3 symmetry and one Ca(2) sites with Cs symmetry. The Eu3+ emission is strongly quenched by Cu2+ ions, and the luminescence decay time is much shorter in the case of Eu3+/Cu2+ co-doped materials than in Eu3+-doped materials. The luminescence quenching mechanism as well as the schematic energy level diagram showing the Eu3+ emission quenching mechanism using Cu2+ ions are proposed. The electron paramagnetic resonance (EPR) technique revealed the existence of at least two different coordination environments for copper(II) ion.

Time response of water-based liquid scintillator from X-ray excitation

The impact of PPO concentration in LAB micelles on the luminescence decay time is determined.

Rigidly linking cyclometallated Ir(iii) and Pt(ii) centres: an efficient approach to strongly absorbing and highly phosphorescent red emitters

Appending a cyclometallated platinum unit onto each of the three ligands of the archetypal fac-Ir(ppy)3 complex leads to a highly efficient red emitter with a short luminescence decay time.

The Luminescent Centra in thin Films of β–Ga2O3 and (Y0.06Ga0.94)2O3

Photoexcitation and photoluminescence spectra of b–Ga2O3 and (Y0.06Ga0.94)2O3 thin films obtained by high-frequency ion-plasmous sputtering was investigated. Luminescence spectra were factorized on ultimate constituents using Alentsev-Fock method. The nature of two intensive luminescent band with maxima in region 3.00 and 3.15 eV and two faint intensive luminescent band with maxima in region 4.00 and 4.25 eV was discussion. Luminescence decay time for band with maximum in region 3.00 and 3.15 eV in different types of b–Ga2O3 and (Y0.06Ga0.94)2O3 thin films was established.

Photoluminescence and photocatalytic activity of zinc tungstate powders

ZnWO4 powders with grain size in range 20 nm–10 µm have been synthesized by a simple combustion method and subsequent calcinations. The photocatalytic activities of powders were tested by degradation of methylene blue solution under UV light. The luminescence spectra and luminescence decay kinetics were studied and luminescence decay time dependence on average powder-grain size was obtained. The correlation between self-trapped exciton luminescence decay time and photocatalytic activity of ZnWO4 powders was shown. A model explaining the excitonic luminescence decay time correlation with photocatalytic activity was proposed.