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Luminescence properties of calcium tungstate activated by lanthanide(Ⅲ) ions

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Journal of Rare Earths 2014年第3期32卷 221-225页

作者： Z.Piskula J.Czajka k.staninski S.Lis Faculty of Chemistry Adam Mickiewicz University Faculty of Chemical Technology and Engineering University of Technology and Life Sciences in Bydgoszcz

Calcium tungstate phosphors activated by the Ln3＋ ions （Ln-Pr, Nd, Tb, Yb） were synthesized by a traditional high-temperature solid-state method. The crystal structures and morphologies of the products were characterized by scanning electron microscopy （SEM）, X-ray powders diffraction （XRD） and infrared spectra （FT-1R）. The samples were fotmd to show luminescence properties （down-conversion, DC, at excitation wavelength 254 nm and up-conversion, UC, at excitation wavelength 980 nm）. CaWO4 doped with Tb3＋/yb3＋ showed green DC and UC luminescence characteristic of Tb（Ⅲ） ion in the range of 470-660 nm, cor- responding to the 5D4→7F6,5,4,3,2 electronic transition. CaWO4 doped with Pr3＋/Yb3＋ showed week blue, green and red （DC and UC） luminescence of Pr（Ⅲ） ion, in the wavelength region of 450-700 nm. Emission peaks were ascribed to the 3P1→3H4,5,6, 3P0→3H4,5,6, 3P1→3F2 and 3P0→3F2 transitions, respectively. CaWO4 doped with Nd3＋/yb3＋ phosphor emitted orange UC luminescence at 450-690 nm （2p3/2→4I15/2, 4G7/2→419/2,11/2,13/2） and strong near-infrared UC luminescence at 720-900 nm （4F7/2＋4S3/2→4419/2, 4F5/2＋2H3/2→419/2, 4F3/2→4I9/2） which is the characteristic of Nd（Ⅲ） ion.

关键词： lanthanides calcium tungstate up-conversion luminescence rare earths

Spectral analysis in ultraweak emissions of chemi-and electrochemiluminescence systems

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Journal of Rare Earths 2009年第4期27卷 593-597页

作者： k.staninski M.kaczmarek S.Lis D.komar A.Szyczewski Faculty of Chemistry Adam Mickiewicz University Faculty of Physics Adam Mickiewicz University

Investigation of ultraweak emissions in the processes of chemiluminescence, CL, and electrochemiluminesce, ECL, requires special techniques of their recording and spectral analysis. From among the hitherto proposed methods of detection of the emission spectra of these processes, that of the cut-off filter was most sensitive. The usefulness of this method in interpretation of the CL and ECL systems of the quantum yields in the range 1×10^-9-1×10^-11 containing ions and complexes of Eu（Ⅲ）, Tb（Ⅲ） and Dy0ID was shown. Exceptional character of the emission bands of lanthanide ions, being a result of the f-f electron transitions and in particular their low FWHM, permitted the appli- cation of the cut-off filter method to their analysis. The results obtained for CL and ECL on the basis of analysis of ultraweak emission proved to be successful in analytical applications. The systems containing Eu（Ⅲ） ions hydrated or complexed with organic ligands enabled inferring changes in the coordination sphere of the ions.

关键词： chemiluminescence electrochemiluminescence cut-off fdter method lanthanide rare earths

Photoluminescence and electrochemiluminescence studies of chosen rare earths systems

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Journal of Rare Earths 2008年第2期26卷 192-197页

作者： Stefan Lis Slawomir But krzysztof staninski Monika Jesiolowska Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University Grunwaldzka 6

Eu（Ⅲ） complexes with chosen keggin polyoxomatalates, POM, containing organic counter cations （tetrabutylarnmonium, tetrabutylphosphonium, triphenylethylphosphonium）, were synthesized, and their photophysical properties were studied. The synthesized complexes had the general formula of XnH5-n[EuSiW11O39], formulated based on the results of elemental and thermogravimetric analysis and FTIR spectroscopy. The photophysical properties of the obtained compounds were investigated using photoluminescence and electrochemiluminescence, ECL, methods in solutions and solids. The most intense luminescence of Eu（Ⅲ） was observed for the complexes with tetrabutylarnmonium cations. After the addition of phenanthroline to the XnH5-n[EuSiW11O39] solutions, a large increase in the Eu（Ⅲ） luminescence intensity and a lengthening of its luminescence lifetime were observed as a result of the formation of ternary complexes. Attempts to apply ECL as a method of light emission by generating species capable of forming excited states in Ln/POMs, i.e., Tb（Ⅲ） and Eu（Ⅲ） in the Na9EuW10O36 and Na9TbW10O36 complexes, were made. The influence of the POM complexes on the ECL was also tested using the Tb/EDDHA （EDDA=ethylenediamine di（o-hydroxyphenylacetic acid）） complex, which is effective in generating ECL.

关键词： Ln(Ⅲ) luminescence electrochemiluminescence polyoxometalates complexes rare earths

kinetic and spectral studies of EHPG systems using chemi-and electrochemiluminescence methods

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Journal of Rare Earths 2010年第6期28卷 868-873页

作者： S. Lis M. kaczmarek k. staninski S. krompiec N. kuznik Faculty of Chemistry Adam Mickiewicz University Institute of Chemistry University of Silesia Faculty of Chemistry Silesian Technical University

The systems containing EHPG, EHPG-OCH3 and EHPG-NH-Ac and Tb(Ⅲ) ions were used to study chemiluminescence (CL) and electrochemiluminescence (ECL) processes. In the CL studies the Fenton system (Fe(Ⅱ)/(Ⅲ)-H2O2) was used as a source of reactive oxygen species (ROS). kinetic CL curves and CL spectral distributions were recorded. On the basis of the results obtained, it was demonstrated that Tb(Ⅲ) acted as a sensitizer. Similarly obtained CL decays in the systems of Fe(Ⅱ)/(Ⅲ)-EHPG (or its derivatives)-H2O2 and Fe(Ⅱ)/(Ⅲ)-EHPG (or its derivatives)-Tb(Ⅲ)-H2O2, independently on the Tb(Ⅲ) concentration, showed that the lanthanide ions did not influence the kinetics of the oxidation of EHPG (or its derivatives) in the Fenton systems. The CL intensity increased with the increasing concentration of Tb(Ⅲ) ions, which were the main emitters in the reaction systems. Spectrophotometric and luminescent studies of the systems before and after the additions of hydrogen peroxide proved that the excitation of the lanthanide ion was a result of energy transfer from the excited products of the oxidation of EHPG or its derivatives to the uncomplexed Tb(Ⅲ) ions. ECL was generated on the surface of a nonstructural modified aluminum electrode with the use of k2S2O8, H2O2 or kN3 as coreactants in aqueous solution. In these studies we employed Al electrodes covered with a 2-4 nm layer of Al2O3 doted with Tb(Ⅲ) or Dy(Ⅲ) ions. The electrodes were polarized using cathodic and anodic pulses of various amplitude and frequency. The relative ECL efficiencies were determined as a function of electric pulse parameters, electrolyte compositions and the thickness of barrier or porous layer of the Al2O3 electrode.

关键词： chemiluminescence lanthanides EHPG complexes rare earths

Luminescence study of europium(III) tris(β-diketonato)/phosphonate complexes in chloroform

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Journal of Rare Earths 2008年第2期26卷 185-191页

作者： Stefan Lis Zbigniew Piskula krzysztof staninski Sayaka Tamaki Masayuki Inoue Yuko Hasegawa Department of Rare Earths Faculty of Chemistry Adam Mickiewicz University Grunwaldzka 6 Department of Chemistry Faculty of Science Science University of Tokyo

The extraction of Eu（Ⅲ） with β-diketone, HA, and monodentate or bidentate Lewis bases, B, into chloroform and the luminescence properties of the extracted species were studied. Pivaloyltrifluoroacetone, Hpta, and 2-thenoyltfifluoroacetone, Htta, were used as the β-diketones. The Lewis bases, B, were tetraethyl methylene diphosphonate, POPO, which was bidentate, and diethyl benzylphosphonate, PhPO which was monodentate. Based on the extraction data, the stability constants, log β, of the first complexes between tfis（β-diketonato）Eu（Ⅲ） and the phosphonate, EuA3B, were determined to be 6.0 for the POPO complex and 3.40 for the PhPO complex. The Eu（Ⅲ） luminescence intensity in the EuA3POPO was larger than EuA3 where A was either pta or tta at similar concentrations of Eu（Ⅲ）, while that in Eu（pta）3PhPO was stronger than EuA3; however, in Eu（tta）3PhPO, it was weaker than Eu（tta）3. The POPO functions as a sensitizer, and the PhPO functions as a quencher for the tta chelate and as a sensitizer for the pta chelate. From the lifetime and quantum yield, φ, of the Eu（Ⅲ） luminescence in the complexes as well as the observation of the extractability of Eu（Ⅲ） with the Hpta and the phosphonates and of the luminescence spectra of the complexes, it was confirmed that the extraction of Eu（Ⅲ） was remarkably enhanced with a β-diketonate and a strong Lewis base, and also the ternary complex that was formed as the extracted species, showed luminescence enhancement. This phenomenon may be due the formation of a strong bond between the Eu（Ⅲ） and the strong Lewis base leading to more hydrophobicity in the extracted species and also to more effective energy transfer from the Lewis base to the Eu（Ⅲ）. It was not significant whether the donor atoms were N or O.

关键词： tris(β-diketonato)Eu(Ⅲ) extraction luminescence phosphonate ligands rare earths