611 resultados para EU3
Resumo:
VUV-UV and Eu-L-3 edge XANES spectra were measured for europium-doped strontium tetraborate prepared by solid state reaction at high temperature in air. The VUV-UV spectra show that the host absorption band of (SrBO7)-O-4 appears below 170 nm. The charge transfer band of Eu3+ doped in SrB4O7 is peaked at 272 nm. The 4f-5d transitions of Eu2+ consist of a band peaked at 310 nm with a shoulder at 280 nm and also include the bands peaked at 238 (weak) and 203 (strong) nm. The result of XANES spectrum at Eu-L3 edge of the synthesized sample indicates that Eu3+ and Eu2+ coexist in SrB4O7:Eu prepared in air, which is consistent with the results of the VUV-UV spectra.
Resumo:
RE3+ (Eu3+, Tb3+) complexes with carboxylic acid (salicylic acid and benzoic acid) were introduced into the sol, which was prepared by the hydrolysis of tetraethoxysilane (TEOS). A sol-gel luminescent thin film (SG-LTF) was then prepared by dispersing the sol onto a silica substrate by a spin coating method. Multi-layer luminescent thin films were prepared by repeating the same process. The luminescent spectra, fluorescence lifetime and thermal stability of the SG-LTFs were investigated. For the reason of comparison polyvinylbutyral (PVB) was added into a N,N-dimethylformamide (DMF) solution in which the comparative RE3+ carboxylic acid complexes were previously dissolved to form the DMF/PVB solution and the PVB luminescent thin film (PVB-LTF) was prepared. The results show that a broad excitation band indicates the formation of RE complexes in the solid SG-LTFs. RE ions, which are restrained in the silica matrix, present longer lifetimes and higher thermal stability than that in the PVB-LTF containing the corresponding pure complexes. The different doping concentration of RE (III) complexes in the SG-LTFs and the different change of the emission intensities with the heat treatment temperature in the sol-gel thin film and the sol-gel bulk gel were also discussed in this paper.
Resumo:
The local structure and the valences of europium in SrBPO5:Eu prepared in air were checked by means of XAFS at Eu-L-3 edge. From the EXAFS results, it was discovered that the doped europium atoms were nine-coordinated by oxygen atoms and the distances of bond Eu-O were 2.42 Angstrom in the host. From the XANES data, it was found that the divalent and trivalent europium coexisted in the matrix. The emission spectra excited by VUV or UV exhibited a prominent broad band due to the 4f(6)5d-4f(7) transition of Eu2+ ions, which indicated that the trivalent europium ions were reduced in air in the matrix at high temperature by the defects [V-Sr]" formed by aliovalent substitution between Sr2+ and Eu3+ ions. The VUV excitation spectra in 100-200 nm range showed that the matrix had absorption bands with the maxima at about 130 and 150 nm, respectively.
Resumo:
Ultrathin multilayer films consisting of the polyoxotungstoeuropate cluster K-12[EuP5W30O110] (EuP5W30) and poly( allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer self-assembly method. The (EuP5W30 /PAH) multilayer films have been characterized by small-angle X-ray reflectivity measurements, X-ray photoelectron spectra, and atomic force microscopy (AFM). From the AFM images, the thickness of the {PEI/PSS/PAH(EuW30/PAH)} multilayer film was estimated to be 6.5 nm, corresponding to an average thickness of ca. 1.1 nm for a EuW30/PAH layer pair. The photoluminescent behavior of the film at room temperature was investigated to show the characteristic Eu3+ emission pattern of D-5(0)-->F-7(J). The fluorescence behavior of the multilayer film is essentially identical to that of H-n[EuP5W30O110]((12-n)-) in a concentrated aqueous solution, except for the relative intensities and peak bandwidths. The occurence of photoluminescent activity confirms the potential for creating luminescent multilayers with polyoxometalates (see ref. 23).
Resumo:
XAFS (EXAFS and XANES) at Eu-L-3 edge were used to determine the local structure and the valences of europium in CaBPO5:Eu prepared in air. The results of EXAFS showed that the doped europium atoms were nine-coordinated by oxygen atoms and the distances of bond Eu-O were 2.39 Angstrom in the host lattice. XANES at Eu-L-3 edge exhibited that Eu2+ and Eu3+ coexisted in the matrix. The luminescent spectrum of the material excited by VUV at 147 nm presented a similar spectrum with that excited by f-f transition of Eu2+ at 396 nm and f-d transition of Eu2+ at 312 nm. The broad emission band due to both 4f(6)5d - 4f(7) transition of EU2+ and f - f transition of Eu3+ could be observed in emission spectra, which indicated that the trivalent europium ions were reduced in air in the matrix at high temperature by the defects [V-Cn]" formed by aliovalent substitution between Ca2+ and Eu3+ ions. The UV excitation spectrum showed the typical f-f transition of Eu3+ and f-d transition of Eu2+. The bands with the maxima at about 113 and 158 nm in VUV excitation spectrum were assigned to originate from the absorption of the host lattice.
Resumo:
Rare-earth and lead ions (Eu3+, Tb3+, Dy3+, Pb2+) doped Ca2Y8 (SiO4)(6)O-2 and Ca2Gd8(SiO4)(6)O-2 thin films have been dip- coated on silicon and quartz glass substrates through the sol- gel route. X- Ray diffraction (XRD), TG- DTA, scanning electron microscopy (SEM), atomic force microscopy (AFM), FT- IR and luminescence excitation and emission spectra as well as luminescence decays were used to characterize the resulting films. The results of XRD reveal that these films remain amorphous below 700 degreesC, begin to crystallize at 800 degreesC and crystallize completely around 1000 degreesC with an oxyapatite structure. The grain structure of the film can be seen clearly from SEM and AFM micrographs, where particles with various shapes and average size of 250 nm can be resolved. Eu3+ and Tb3+ show their characteristic red (D-5(0)-F-7(2)) and green (D-5(4) - F-7(5)) emission in the films with a quenching concentration of 10 and 6 mol% (of Y3+), respectively. The lifetime and emission intensity of Eu3+ increase with the temperature treatment from 700 to 1100 degreesC, while those of Tb3+ show a maximum at 800 degreesC. Energy transfer phenomena have been observed by activating the oxyapatite film host- lattice Ca2Gd8(SiO4)(6)O-2 with Tb3+ (Dy3+). In addition, Pb2+ can sensitize the Gd3+ sublattice in Ca2Gd8(SiO4)(6)O-2.
Resumo:
La2CaB10O19Eu3+UV VUV,Eu3+,Eu3+O2-La3+,Eu3+O2-Ca2+,Eu3+(CTB)244nm,130170nmEu3+f d
Resumo:
Pechini Y2O3Eu3+,,560mY2O3Eu3+X(XRD) (FT IR)(AFM),(PL)XRD500,900,(50%)Y2O3Eu3+,Eu3+5D0 7FJ(J=0,1,2,3,4),
Resumo:
ZnGa2 O4ZnGa2 O4Mn2 + /Eu3 + ,X(XRD) (TG DTA)ZnGa2 O4ZnGa2 O4Mn2 + /Eu3 + XRD , 5 0 0 , 70 0ZnGa2 O4 , 5 0 0ZnGa2 O4Mn2 + 4 5 0nm 5 0 6nm ,ZnGa2 O4 ,Mn2 + 4T16A1ZnGa2 O4Eu3 + Eu3 + , 6 13nm ,Eu3 + 5D0 7F2 ZnGa2 O4Mn2 + /Eu3 + ,
Resumo:
,(TRFIA).(DTPAA).Eu3+(RAH)IgG,(DELFIA),Eu3+-(-NTA),,,110-7110-11 gmL-1,110-13 gmL-1,6.4%.TRFIA,(Anti-HCV).(ELISA).TRFIAELISA.
Resumo:
-..Eu3+;H2S;TEM..
Resumo:
Y2 O3Eu3+ 0 .0 5,A+ 0 .0 2 (A =LiNaK)Y2 O3Eu3+ 0 .0 5,B2 + 0 .0 2 (B =MgCaSrBa) :Y2 O3Eu3+ Y2 O3Eu3+ (611nm) ,Eu3+ 5D0 7F2 ;Y2 O3Eu3+ ,Y2 O3Eu3+ ,A+ (A =LiNaK) ,Y2 O3Eu3+ B2 + (B =MgCaSrBa)CaSrBaMg , ,Y2 O3Eu3+ ,A+ 175 , 0 .966eV ;Y2 O3Eu3+ ,B2 + 192 (Ca)164 (Sr)1...
Resumo:
Eu3+ ,Zn2 + ,Cd2 + ,Co2 + ,Ni2 + ,Cu2 + ,Mn2 + ,Mg2 + , , , . , , Eu3+ , Co2 + Ni2 + ,Zn2 + Cd2 +
Resumo:
(La3 + ,Eu3 + ,Dy3 + ,Yb3 + ) - , - ( )Tb -A2 . <3mol/LA2 , 5 mol/L ;Ca2 + , ; ;Tb - 10 mol/L
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(Eu3+Tb3+)1,10 ,,,,,,,64
