X‐ray K emission spectra of vanadium in various oxidation states

Yasuda, Seiji; Kakiyama, Hitoo

doi:10.1002/xrs.1300070108

Cited by 19 publications

(24 citation statements)

References 6 publications

(1 reference statement)

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“…This is consistent with the previous measurements of photoinduced x-ray fluorescence spectra measured by Kawai et al 17 Also, available data for Cr, V and Mn compounds confirm that the measured K˛shifts are generally less than about 0.5 eV. 3,6,9 For the CuO and Cu 2 O oxides, energy shifts of 0.11 and 0.13 eV have been reported, 18 whereas maximum energy shifts up to š0.2 eV have been measured for many Ni intermetallic compounds and alloys. 19 This trend of small K˛energy shifts for the 3d transition and late transition elements has therefore been also confirmed by our experiment.…”

Section: The Case Of Tisupporting

confidence: 92%

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Chemical state analysis employing sub‐natural linewidth resolution PIXE measurements of Kα diagram lines

2005

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A high-energy resolution crystal spectrometer in Johansson geometry, which allows energy resolution below the natural linewidth of the Ka diagram lines, was employed in the measurements of proton-induced Ka x-ray emission spectra of titanium and sulfur pure and compound targets. The results demonstrate a clear dependence of the Ka energy shifts on the chemical state of the element in the sample. This dependence permits the chemical state speciation of low-Z elements in an unknown sample by employing high-resolution PIXE measurements of the Ka line. The potential of the technique in speciation studies is demonstrated in the case of an aerosol sample. The analysis of the Ka line obtained from the high-energy resolution proton-induced S Ka x-ray spectrum allowed the identification of sulfur in the aerosol sample as sulfate ([SO 4 ] 2− ).

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Section: The Case Of Tisupporting

confidence: 92%

“…Therefore, it seems more appropriate that for the 3d transition elements chemical speciation has to be carried out via the Kˇ1 ,3 emission lines, where the observed energy shifts range from about 0.4 eV up to more than 1 eV, or through other characteristics of the emission spectra than energy shifts. 1,3,6…”

Section: The Case Of Timentioning

confidence: 99%

Chemical state analysis employing sub‐natural linewidth resolution PIXE measurements of Kα diagram lines

2005

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“…The chemical shifts with respect to V metal were reported to À0:1, À0:3-À0:4, and À0:5-À0:6 eV for V III , V IV , and V V compounds, respectively. 10 Figure 2 shows the normalized V K-edge XANES spectra. In the case of V/TiO 2 (a and b), the rising edge appeared at 5480.8-5481.1 eV.…”

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confidence: 99%

0.6–3.0 wt% of Vanadium on/in Titania Monitored by X-ray Absorption Fine Structure Combined with Fluorescence Spectrometry

Izumi¹,

Kiyotaki²,

Yoshitake³

et al. 2002

Chemistry Letters

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Selective XAFS measurements of 0.6-3.0 wt% V sites on/in TiO 2 were enabled utilizing a fluorescence spectrometer. The V sites were V IV species in the case of high-surface-area V-TiO 2 in contrast to V V species in the case of conventional V/TiO 2 catalysts, V supported on HSA-TiO 2 , and V-TiO 2 prepared in the absence of dodecylamine (general sol-gel method).Vanadium catalysts are used for the reduction of nitric oxide with ammonia, 1 the oxidation of naphthalene/o-xylene to phthalic anhydride, and the oxidation of butane to maleic anhydride. 2 The optimal catalytic performance in these applications has been reported to correspond to concentrations of V of less than a monolayer, dispersed on TiO 2 . When the concentration of V corresponds to monolayer levels, major V species has been proposed to be a monomeric monooxo 3 or dioxo vanadate, 4 polyvanadates 3 such as decavanadate ([V 10 O 28 ] 6À ), 5 or to an epitaxial V 2 O 5 (010) layer over TiO 2 6 by Raman, 51 V NMR, UVvisible, etc.XAFS directly determines the local structure of non-crystalline materials. However, exceptionally it is very difficult to measure XAFS data for low concentrations of V in the TiO 2 matrix. When 0.6 wt% of V (1.1 wt% V 2 O 5 ) is mixed with TiO 2 , the V K-edge jump is only 0.037 compared to a total absorption of 4 in transmission mode. The photon number ratio of V K 1 /Ti K 1 is only 0.012 in fluorescence mode. When a solid-state detector (SSD; ÁE % 100 eV) is used, the V K 1 (4952.2 eV) peak can be separated from the Ti K 1 (4510.8 eV) peak. However, the Ti K 1;3 (4931.8 eV) still overlaps the V K 1 . The ratio of V K 1 /Ti K 1;3 is 0.058. The selective detection of V K 1;3 (5427.3 eV) is difficult using the SSD because scattered X-rays overlap. Auger or secondary photoelectrons derived from V are selectively monitored using an electron energy analyzer. However, these experiments need ultra-high vacuum, and in-situ measurements are impossible. In this Letter, XAFS combined with fluorescence spectrometry 7;8 was applied to selectively monitor low concentrations of V on/in TiO 2 .TiO 2 (P25, 60 m 2 g À1 ) was impregnated with V triisopropoxide oxide (1) in isopropanol solution (V/TiO 2 ). A high surface area (HSA; 1200 m 2 g À1 ) V-TiO 2 was prepared from compound 1, Ti tetraisopropoxide (2), and dodecylamine. 9 An aqueous solution was kept at 333 K for six days, and filtered. The obtained powder was heated at 453 K for ten days, and then washed by p-toluenesulfonic acid/ethanol. HSA-TiO 2 prepared in a similar procedure was impregnated with compound 1 (V/HSA-TiO 2 ). V-TiO 2 was prepared from compounds 1 and 2 in the absence of docecylamine in a similar manner to the case of HSA V-TiO 2 . In all cases, the dried powder was heated in air at 473 K and pressed into a disk in ambient air.The XAFS spectra were measured at KEK-PF 7C. The storage ring energy was 2.5 GeV, and the current was 390-270 mA. A Si(111) double crystal monochromator was used. The beam was focused and fully tuned. The X-ray fluorescence from the sample was analyze...

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“…All numerical values used for parametrization are presented in Table 2 12 JON for Jones and Urch, 53 BES for Best, 50 TIR for Tirao et al, 43 TOR for Torres Deluigi et al, 44 UR S for Ur si c et al, 51 BER for Bergmann et al, 37 MUK for Mukoyama et al, 21 ASA for Asada et al, 67 IIH for Iihara et al, 52 TSU for Tsutsumi et al, 9 and YAS for Yasuda and Kakiyama. 68 ODB stands for ''our database''.…”

Section: Relative Intensitiesmentioning

confidence: 99%

Parametrization of Kβ′′ and Kβ2,5 X-ray contributions in Kβ spectra of 3d transition metal compounds

Fazinić

Mandić

Kavčič

et al. 2011

J. Anal. At. Spectrom.

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Large database of high resolution Kb X-ray emission spectra of selected 3d metal (Ti, V, Cr, Mn) compounds obtained after excitation by 2 and 3 MeV proton beams have been built. Analysis of (relative) positions and intensities of Kb 00 and Kb 2,5 X-ray contributions as a function of chemical and structural properties of analyzed 3d metal compounds have been performed. Two independent experiments employing wavelength dispersive spectrometers with different experimental resolutions (8.1 eV versus 2.8 eV for the case of Cr Kb 1,3 line FWHM) were performed in order to exclude any possible effect of the experimental resolution on the extracted values. A simple parametrization of Kb 00 and Kb 2,5 X-rays' relative positions and intensities over the range of 3d metal compounds with various oxidation states, a wide range of metal-ligand bond lengths, and selected 3d metals, was performed. Results of our parametrization were compared critically with other experimental and theoretical values available in the literature. The parametrization obtained in this work could be used for chemical and structural speciation of 3d metal compounds and for improved interpretation of K X-ray spectra of 3d transition metal compounds measured by solid state detectors.

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X‐ray K emission spectra of vanadium in various oxidation states

Cited by 19 publications

References 6 publications

Chemical state analysis employing sub‐natural linewidth resolution PIXE measurements of Kα diagram lines

Chemical state analysis employing sub‐natural linewidth resolution PIXE measurements of Kα diagram lines

0.6–3.0 wt% of Vanadium on/in Titania Monitored by X-ray Absorption Fine Structure Combined with Fluorescence Spectrometry

Parametrization of Kβ′′ and Kβ2,5 X-ray contributions in Kβ spectra of 3d transition metal compounds

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