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in a cell with kapton windows in order to avoid contact with air. Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) experiments were performed at the Pt L 3 and Ge K edges. Three ion chambers were

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Akiyama, K. Sueki, H. Haba, K. Tsukada, M. Asai, T. Yaita, Y. Nagame, K. Kikuchi, M. Katada, and H. Nakahara

Abstract  

We have, previously, reported on the HPLC elution behavior of the Th, Pa, U, Np, and Am metallofullerenes and the UV/vis/NIR absorption spectra of the Th@C84 and U@C82 species. In this paper, the followings are reported: (1) Pu metallofullerenes were produced and their HPLC elution behavior was investigated using a radiotracer technique. The HPLC chromatogram of this metallofullerene was found to be almost the same as that of the Np and Am metallofullerenes. (2) The oxidation states of Th@C84 and U@C82 produced in macroscopic quantities were examined by XANES (X-ray absorption near edge structure) measurements. The oxidation state of the U atom in the C82 fullerene cage was estimated to be 3+ with the formal charge of the ionic molecule being U3+@C82 3-.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Yinsong Wang, Aiguo Li, Yuanxun Zhan, Lun Wei, Yan Li, Guilin Zhang, Yaning Xie, Jing Zhang, Yuanmao Zhang, and Zuci Shan

Abstract  

The atmospheric particulate matter samples were collected in Shanghai, China. The X-ray absorption near-edge structure (XANES) spectra of Cr, Mn, Cu and Zn were measured. The XANES spectroscopy was used as a fingerprint to compare with that of reference materials to obtain speciation information. The oxidation state of these elements and main chemical components in the samples were described using the method. The results show that in our samples the oxidation state of Cr is trivalent, Mn mainly exists in the divalent state, Cu also exists in the divalent state, and Zn mainly exists in the zinc sulfate. For the XANES spectra of samples with different particle size and from different sampling site, we did not find their obvious differences. When we compared the XANES spectra of our samples with those of standard reference material SRM 1648, we found that they are similar in regards to the determined elements. The elemental concentrations in the samples were determined by proton induced X-ray emission (PIXE). The difference of elemental concentrations was observed in the different samples.

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Summary  

A method has been developed for analyzing pyrite quantitatively in the sediments of Erhai Lake in southwest China using 57Fe Mössbauer spectroscopy combined with a series of acidic pre-treatments. Following a washing with an alkaline solution (0.1N NaOH), the sediment samples were successively treated using HCl, HF, and then HCl (65 °C). The residues thus prepared were analyzed for pyrite using 57Fe Mössbauer spectrometry. The presence of pyrite was also confirmed in the acidic residues of the sediments using sulfur K-edge X-ray absorption near edge structure. This method can be used to measure pyrite in aquatic sediments, especially when the concentration of pyrite is very low and the particles of pyrite are small or the crystallinity is low, and even in amorphous status. In addition, vertical variations of pyrite contents are positively correlated with organic matter and negatively correlated with hematite, superfine paramagnetic ferric iron and sedimentation rate in the cored sediment from the Erhai Lake. All these geochemical indicators may also reflect environmental changes in sedimentation conditions and diagenesis.

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Abstract  

Two complimentary spectroscopic techniques, X-ray absorption and fluorescence spectroscopy have been conducted at spatial scales of 1 to 25 μm on uranium contaminated soil sediments collected from two former nuclear materials processing facilities of the DOE: Fernald, OH and Savannah River Site, SC. A method of imbedding particles in a non-reactive Si polymer was developed such that individual particles could be examined before and after extraction with a wide range of chemicals typically used in sequential extraction techniques and others proposed forex situ chemical intervention technologies. Using both the micro-X-ray fluorescence (XRF) and micro-X-ray Absorption Near Edge Structure (XANES) techniques, both elemental and oxidation state distribution maps were generated on individual particles before and following chemical extraction. XANES can determine the relative proportion of U(VI) and U(IV) in phases comprising individual particles before and after extraction and showed that greater than 85% of the uranium existed as hexavalent U(VI). Fluorescence spectra of contaminated particles containing mainly U(VI) revealed populations of uranyl hydroxide phases and demonstrated the relative efficacy and specificity of each extraction method. Correlation of XAS and fluorescence data at micron scales provides information of U oxidation state as well as chemical form in heterogeneous samples.

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Abstract  

XANES has been recently used for the determination of oxidation states of actinides in environmental samples. To obtain reliable results, however, a sufficiently long counting time at every probing energy and a large number of experimental points per XANES spectrum are required, due to the complex mathematical model used to fit the measured spectrum. This makes micro-mapping difficult, since the time required for data collection becomes unacceptably long. A simplified model for data collection and evaluation is presented. Its effectiveness has been tested by measuring the distribution of Pu oxidation states in a “hot” particle coming from a nuclear weapon test site.

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can apply other methods, such as X-ray absorption near edge structure (XANES) measurements [ 14 ], or thermogravimetric (TG) measurements, as well as the method based on balancing components estimated in the XRF. These methods can be used also for

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Journal of Thermal Analysis and Calorimetry
Authors: Hermi F. Brito, Jukka Hassinen, Jorma Hölsä, Högne Jungner, Taneli Laamanen, Mika Lastusaari, Marja Malkamäki, Janne Niittykoski, Pavel Novák, and Lucas C. V. Rodrigues

been proven by the observation of defect-related luminescence from non-doped Sr 2 MgSi 2 O 7 at 10 K [ 22 ]. Also, XANES (X-ray Absorption Near Edge Structure) measurements have shown that the co-dopants are always trivalent in the Sr 2 MgSi 2 O 7 :Eu

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. 24. Bolis , V , Maggiorini , S , Meda , L , D’Acapito , F , Palomino , GT , Bordiga , S et al. 2000 X-ray photoelectron spectroscopy and X-ray absorption near edge structure study of copper sites hosted at the

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