Synthesis and Photoluminescence Properties of Doped Europium Complexes with 2-Pyrazinecarboxylate

2011 ◽  
Vol 399-401 ◽  
pp. 963-966
Author(s):  
Hai Xia Zhang ◽  
Rui Jun Ma ◽  
Hai Bin Chu ◽  
Ming Yan Zhao ◽  
Ying Nan Chen ◽  
...  

Seven europium complexes of 2-pyrazinecarboxylate (pyca) doped with inert fluorescent lanthanide ions (La3+, Y3+) have been synthesized. Elemental analysis, IR spectroscopy, absorption spectroscopy and TG-DSC analysis showed that the complexes have the formulas of Eu(pyca)3•3H2O and EuxRE1-x(pyca)3•3H2O (RE=La, Y; x = 0.7,0.5,0.3), respectively. The lanthanide ions coordinated with carboxylic oxygen atoms and nitrogen atoms of pyca. Luminescence spectra and luminescence life-times of the complexes have been measured and their quantum yields were calculated. The results showed that the existence of La3+and Y3+ions could enhance the luminescence intensity and quantum yield of the europium complexes, which may arise from the intramolecular energy transfer between the inert fluorescent lanthanide ions and Eu3+ion. Those doped complexes have the advantages of strong luminescence, low cost and practical application value.

2012 ◽  
Vol 271-272 ◽  
pp. 55-59
Author(s):  
Ming Yan Zhao ◽  
Rui Jun Ma ◽  
Ying Nan Chen ◽  
Hai Xia Zhang ◽  
Kai Kong ◽  
...  

Nine europium complexes with 2-pyrazinecarboxylic acid (Hpyca) and butanedioic acid (HBDA) were synthesized and characterized by elemental, IR, EDTA titration, ICP, and TG-DSC analyses. The results show that the complexes have the compositions of Eu(Pyca)(BDA)•2H2O, Eu0.7La0.3(Pyca)(BDA)•2H2O, Eu0.6La0.4(pyca)(BDA)•3H2O, Eu0.5La0.5(pyca)(BDA)•4H2O, Eu0.7Y0.3(Pyca)(BDA)•3H2O, Eu0.6Y0.4 (Pyca)(BDA)•2H2O, Eu0.5Y0.5(Pyca)(BDA)•3H2O, Eu0.7Gd0.3(Pyca)(BDA)•2H2O and Eu0.5Gd0.5(Pyca)(BDA)•2H2O. IR spectra indicate that lanthanide ions coordinate with the carboxylic oxygen atoms and nitrogen atoms of Hpyca and oxygen atoms of HBDA. Luminescence spectra show that the introduction of La3+, Y3+ or Gd3+ in the complexes does not change the luminescence peak position, but remarkably increases luminescent intensity of the europium complexes. The quantum yields of the complexes doped with inert lanthanide ions (La3+, Y3+ or Gd3+) are higher than that of the undoped europium complex. Furthermore, doping the inert lanthanide ions in right proportion can increase the luminescence lifetimes of complexes. Those complexes are of strong luminescence, low cost and practical value.


2013 ◽  
Vol 750-752 ◽  
pp. 1007-1010
Author(s):  
Ai Ling Wang ◽  
Hai Xia Zhang ◽  
Kai Kong ◽  
Huan Huan Li ◽  
Hua Wang ◽  
...  

Ten kinds of terbium doped inert yttrium complexes with 2,3-pyrazinedicarboxylate (2,3-pzdc2-) have been synthesized. Characterization results indicate that the complexes have the compositions of Tb (pzdc)1.55H2O and TbxYy(pzdc)1.55H2O (x:y=0.10:0.90; 0.20:0.80; 0.30:0.70; 0.40:0.60; 0.60:0.40; 0.70:0.30; 0.80:0.20; 0.90:0.10). IR spectra show that the lanthanide ions coordinate with the carboxylic oxygen atoms and nitrogen atoms of the ligands. Luminescence spectra show that the Y(III) ions can remarkably increase the luminescent intensities of terbium complexes. And Tb0.7Y0.3(pzdc)1.55H2O exhibits the strongest luminescent emission. Furthermore, the doped lanthanide complexes show longer luminescence lifetimes and higher quantum yields. The enhanced luminescence efficiencies of Tb3+ions in the doped complexes may result from intramolecular energy transfer as well as the decrease of the self-quench of the Tb3+ions induced by the doped Y(III) ions.


2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>


2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>


2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>


2020 ◽  
Author(s):  
Xiaojing Xia ◽  
Anupum Pant ◽  
Xuezhe Zhou ◽  
Elena Dobretsova ◽  
Alex Bard ◽  
...  

Fluoride crystals, due to their low phonon energies, are attractive hosts of trivalent lanthanide ions for applications in upconverting phosphors, quantum information science, and solid-state laser refrigeration. In this article, we report the rapid, low-cost hydrothermal synthesis of potassium lutetium fluoride (KLF) microcrystals for applications in solid-state laser refrigeration. Four crystalline phases were synthesized, namely orthorhombic K<sub>2</sub>LuF<sub>5</sub> (Pnma), trigonal KLuF<sub>4</sub> (P3<sub>1</sub>21), orthorhombic KLu<sub>2</sub>F<sub>7</sub> (Pna2<sub>1</sub>), and cubic KLu<sub>3</sub>F<sub>10</sub> (Fm3m), with each phase exhibiting unique microcrystalline morphologies. Luminescence spectra and emission lifetimes of the four crystalline phases were characterized based on the point-group symmetry of trivalent cations. Laser refrigeration was measured by observing both the optomechanical eigenfrequencies of microcrystals on cantilevers in vacuum, and also the Brownian dynamics of optically trapped microcrystals in water. Among all four crystalline phases, the most significant cooling was observed for 10%Yb:KLuF<sub>4</sub> with cooling of 8.6 $\pm$ 2.1 K below room temperature. Reduced heating was observed with 10%Yb:K<sub>2</sub>LuF<sub>5</sub>


2021 ◽  
Author(s):  
Jingjing Yu ◽  
Bihao Hu ◽  
Chuanlan Xu ◽  
Jiazhi Meng ◽  
Shu Yang ◽  
...  

Nickel is widely researched in the electrooxidation of borohydride due to its low cost and abundant reserves, but it’s catalytic activity and stability need to be improved for practical application....


2018 ◽  
Vol 57 (13) ◽  
pp. 7512-7515 ◽  
Author(s):  
Chen Wei ◽  
Boxun Sun ◽  
Zelun Cai ◽  
Zifeng Zhao ◽  
Yu Tan ◽  
...  

1996 ◽  
Vol 422 ◽  
Author(s):  
H. Horiguchi ◽  
T. Kinone ◽  
R. Saito ◽  
T. Kimura ◽  
T. Ikoma

AbstractErbium films are evaporated on crystalline silicon substrates and are thermally diffused into silicon in an Ar+02 or H2 flow. Very sharp Er3+-related luminescence peaks are observed around 1.54 μ m.The main peak as well as the fine structures of the luminescence spectra depend on the annealing atmosphere, suggesting different luminescence centers. The full width at half maximum (FWHM) of the main peaks is ≤ 0.5nm at 20K. Thermal diffusion with Al films on top of the Er films is found to increase the intensity of the Er3+-related peaks greatly. The temperature dependence between 20 K and room temperature is relatively small, and a strong luminescence is obtained at room temperature.


2016 ◽  
Vol 12 ◽  
pp. 825-834 ◽  
Author(s):  
Andreea Petronela Diac ◽  
Ana-Maria Ţepeş ◽  
Albert Soran ◽  
Ion Grosu ◽  
Anamaria Terec ◽  
...  

New indeno[1,2-c]pyran-3-ones bearing different substituents at the pyran moiety were synthesized and their photophysical properties were investigated. In solution all compounds were found to be blue emitters and the trans isomers exhibited significantly higher fluorescence quantum yields (relative to 9,10-diphenylanthracene) as compared to the corresponding cis isomers. The solid-state fluorescence spectra revealed an important red shift of λmax due to intermolecular interactions in the lattice, along with an emission-band broadening, as compared to the solution fluorescence spectra.


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