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1

X-Ray Absorption Near Edge Structure and Mössbauer Spectroscopy in Study of Iron Valence States in Tissues

100%

Dziedzic-Kocurek K., Banaś A., Kwiatek W., Stanek J.

Acta Physica Polonica A

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2006

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vol. 109

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issue 3

341-345

EN

X-ray absorption near edge structure Fe K-edge spectra and ^{57}Fe Mössbauer spectra of selected standard compounds were recorded at room temperature. Valence and spin states of Fe in these samples known from Mössbauer spectroscopy were correlated with the shapes of X-ray absorption near edge structure spectra in search of possible application of X-ray absorption near edge structure spectroscopy as analytical tool determining local electronic states of iron in tissues. As an example, the X-ray absorption near edge structure spectra of healthy and cancerous tissues of prostate are shown, suggesting Fe^{3+} in cancerous tissues.

2

XANES Study of La_{0.75-x}Gd_xCa_{0.25}MnO_{3-δ} Solid Solutions

100%

Drozd V., Pęka̶a M., Liu R., Lee J., Chen J.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

583-589

EN

A series of solid solutions La_{0. 75-x}Gd_xCa_{0.25}MnO_{3-δ} with 0.0≤x≤0.75 was prepared via carbonate precursor precipitation method. Final sintering was performed at 1250ºC in oxygen flow atmosphere. The samples obtained were characterized by scanning electron microscope, X-ray diffraction measurements. Oxygen stoichiometry was analyzed by iodometric titration method. X-ray absorption spectroscopic methods of Mn L-edge and Mn K-edge X-ray absorption near edge structure were used to study oxidation state of manganese in the solid solutions and elucidate features of their local crystal structure. Orthorhombic crystal structure characteristics of the solid solutions were refined by Rietveld method. An increase in oxygen deficiency and average manganese oxidation state were found to accompany Gd concentration increase in La_{0.75-x}Gd_xCa_{0.25}MnO_{3-δ}. These results are consistent with Mn L-edge X-ray absorption near edge structure spectra, where a gradual change of Mn oxidation state with Gd concentration increase was detected. Origins of oxygen deficiency La_{0.75- x}Gd_xCa_{0.25}MnO_{3-δ} are discussed in terms of structural disorder caused by Gd substitution for La.

3

C_{60}FeC_{60} Complexes in Fe Intercalated Fullerite Studied by X-Ray Absorption

80%

Sobczak E., Traverse A., Nietubyć R., Swilem Y., Byszewski P., Żymierska D.

Acta Physica Polonica A

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1997

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vol. 91

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issue 5

877-881

EN

The aim of Fe K edge XANES and EXAFS studies is to reveal the local structure around Fe ions in C_{60}Fe_{x} intercalated fullerites. The measurements are performed in transmission mode at LN_{2} temperature for C_{60}Fe_{x} powder samples and other materials: ferrocene Fe(C_{5}H_{5})_{2}, Fe metal foil and α-Fe_{2}O_{3}. The main result is that the XAFS spectra of the C_{60}Fe_{2} intercalate is almost identical to that of ferrocene and very different from α-Fe and α-Fe_{2}O_{3}. The results support opinion that in the C_{60}Fe_{x} intercalates the ferrocene-like bonds in complexes C_{60}FeC_{60} are formed. Additionally, the XAFS spectra showed that neither remarkable amount of Fe metallic clusters nor oxidized iron particles are present in the C_{60}Fe_{x} sample.

4

X-Ray Absorption Studies of Fe_{73.5}Cu_{1}Nb_{3}Si_{15.5}B_{7} Amorphous and Nanocrystalline Alloys

80%

Swilem Y., Sobczak E., Nietubyć R., Ślawska-Waniewska A., Dynowska E.

Acta Physica Polonica A

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1997

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vol. 91

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issue 5

883-886

EN

The nanocrystalline state of the formally amorphous alloy Fe_{73.5}Cu_{1}Nb_{3}Si_{15.5}B_{7} is achieved by a heat treatment at temperatures between 500°C and 600°C. The XANES and EXAFS methods were applied for investigation of local structure and chemical bonding around Fe atoms in amorphous and nanocrystalline alloys. The Fe K absorption spectra were measured in the transmission mode at room temperature for Fe_{73.5}Cu_{1}Nb_{3}Si_{15.5}B_{7} amorphous and nanocrystalline alloys and compared with the spectra for Fe metallic foil and Fe_{3}Si polycrystalline samples.

5

Fe Clusters in Fe Intercalated Fullerite

80%

Sobczak E., Żymierska D., Byszewski P., Traverse A.

Acta Physica Polonica A

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1997

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vol. 91

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issue 2

447-450

EN

The local structure around Fe ions in the C_{60}Fe_{2} fullerites before and after heat treatment in temperature of 850 K was investigated by means of Fe K edge X-ray absorption near edge structure and extended X-ray absorption near edge structure methods. The X-ray absorption measurements were performed at liquid nitrogen temperature using synchrotron radiation in transmission mode. The X-ray absorption near edge structure and extended X-ray absorption near edge structure studies showed that the heat treatment of the C_{60}Fe_{2} fullerite at temperature 850 K causing an irreversible transition from monoclinic to fcc structure is accompanied with changes in the state of Fe ions, part of them forms clusters in bcc structure, while others turn to Fe^{3+} ions bonded to fullerenes.

6

Laboratory Dispersive EXAFS Spectrometer

80%

Mosset A., Lecante P., Baules P., Jaud J., Galy J., Burian A.

Acta Physica Polonica A

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1997

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vol. 91

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issue 4

825-828

EN

We report on a laboratory EXAFS spectrometer optimized for transmission dispersive mode. Absorption edges ranging from 6 to 20keV can be studied. Factors determining energy range and resolution are detailed. A new asymmetric geometry which allows to use all the lattice planes of the dispersing crystal is described and the choice of the best plane analysed. EXAFS spectra of Cu metal and Cu acetate, obtained on this laboratory facility, are compared to the corresponding spectra recorded on the French synchrotron facility (LURE).

7

Optical Investigation of ZnO Nanowires

80%

Martínez-Criado G., Hernández-Vélez M., Letard I., Cros A., Cantarero A., Mínguez-Bacho I., Susini J., Tucoulou R., Sans J., Sanz R., Vázquez M.

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issue 2

369-373

EN

In this study we report the application of synchrotron X-ray fluorescence, photoluminescence and Raman scattering techniques to the analysis of the incorporation of impurities in unintentionally doped ZnO nanowires. Highly ordered one-dimensional ZnO arrays were fabricated by an oxidation process of Zn metal electrodeposited in nanoporous anodic alumina template. X-ray fluorescence data show the contribution of residual elements into the ZnO nanowires growth. A rough analytical quantification of the main light and heavy chemical contents derives impurity concentrations below 1%. The optical efficiency of ZnO nanowires is strongly affected by non-radiative centers up to temperatures as low as 100 K. The photoluminescence was found to be totally dominated by optical transitions associated with the anodic alumina template. Finally, the Raman scattering provides no evidence of local vibrational modes or secondary phases, but it shows the unambiguous signature of the ZnO hexagonal phase.

8

Solid State Ion Exchange Reactions of Co with Zeolites

61%

Jentys A., Lugstein A., Vinek H.

Acta Physica Polonica A

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1997

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vol. 91

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issue 5

969-974

EN

Co cations were introduced into ZSM5 and faujasite type zeolites by solid state ion exchange. On both types of zeolites the solid state reaction led to an exchange of all protons. On ZSM5 one proton was exchanged with one Co^{2+} cation, while on the faujasite samples two protons were exchanged with one Co^{2+} cation. After the incorporation of cobalt two new Lewis acid sites were observed on the CoZSM5 and CoY samples.

Refine search results

X-Ray Absorption Near Edge Structure and Mössbauer Spectroscopy in Study of Iron Valence States in Tissues

XANES Study of La_{0.75-x}Gd_xCa_{0.25}MnO_{3-δ} Solid Solutions

C_{60}FeC_{60} Complexes in Fe Intercalated Fullerite Studied by X-Ray Absorption

X-Ray Absorption Studies of Fe_{73.5}Cu_{1}Nb_{3}Si_{15.5}B_{7} Amorphous and Nanocrystalline Alloys

Fe Clusters in Fe Intercalated Fullerite

Laboratory Dispersive EXAFS Spectrometer

Optical Investigation of ZnO Nanowires

Solid State Ion Exchange Reactions of Co with Zeolites