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1Author    Hiroyuki Ishida, Hironobu Maeda, Akiko Hirano, Tamotsu Fujimoto, Yoshihiro Kubozono, Setsuo Kashino, Shuichi EmuraRequires cookie*
 Title    E X A F S S tu d y o n th e P h a s e T r a n s itio n ( P h a s e a ' -5) in C H 3 N H 3 I  
 Abstract    The local structure of CH3NH3I around the I" ion in Phase a 'and 8 was studied by iodine K-edge EXAFS. The crystal structure in Phase a ' was redetermined by single crystal X-ray diffraction. The Debye-Waller factor <r(2) derived from EXAFS spectra shows an anomalous behavior around the order-disorder transition temperature from Phase 8 to a '. The phase transition has been interpreted as the disordering process which involves not only the H atoms but also the C atoms in the cation. 
  Reference    Z. Naturforsch. 50a, 876—880 (1995); received June 16 1995 
  Published    1995 
  Keywords    Crystal structure, EXAFS, Phase transition, X-ray diffraction 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0876.pdf 
 Identifier    ZNA-1995-50a-0876 
 Volume    50 
2Author    J. M. Ramallo-López, F. G. Requejo, A. G. Bibiloni, M. Rentería, L. Gutierrez, E. E. MiróRequires cookie*
 Title    Combined TDPAC and EXAFS Study of InPt/FER Catalysts  
 Abstract    Time Differential Perturbed Angular Correlation (TDPAC) experiments using 111 In as probe were performed in order to determine the nature of In-sites in In-ferrierite (In/FER), before and after the incorporation of Pt through the hyperfine interaction between the nuclear quadrupole moment of the probe's nucleus and the extranuclear electric field gradient (EFG). Extended X-ray Absorption Fine Structure (EXAFS) measurements were performed to measure the absorbance above the Pt's L m absorption edge in the transmission mode in order to determine the local environment of Pt atoms in Pt/FER and InPt/FER catalysts. TDPAC spectra of 111 In in In/FER and InPt/FER taken at 500°C in air indicated that there are no changes in the indium surroundings after the incorporation of Pt. Three sites were found for indium in both samples. Two of them correspond to the two sites of indium in ln 2 0 3 and the third one is attributed to In in exchange sites of the zeolites. Their population, quadrupole frequencies and asymmetry parameters didn't change with the incorporation of Pt. EXAFS experiments showed similar near neighborhood Pt-0 distances and Pt coordination number in Pt/FER and InPt/FER samples. There is no evidence of the presence of any In-Pt bimetallic entity in InPt/FER catalyst. 
  Reference    Z. Naturforsch. 55a, 327—330 (2000); received August 26 1999 
  Published    2000 
  Keywords    Hyperfine Interactions, TDPAC, EXAFS, Catalysis, Ferrierite 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0327.pdf 
 Identifier    ZNA-2000-55a-0327 
 Volume    55 
3Author    Yasuhiro Inada3, Shigenobu FunahashibRequires cookie*
 Title    Equilibrium and Structural Study of Chloro Complexes of Iron(III) Ion in Acidic Aqueous Solution by Means of X-Ray Absorption Spectroscopy  
 Abstract    Using an extended X-ray absorption fine structure (EXAFS) technique, the formation constant of the pentaaquachloroiron(III) complex was determined to be 3.8 ± 0.4 mol-1 dm3 at 25.0 ± 0 .1 °C in a 1.00 mol dm-3 H C I O 4 aqueous solution. The structures of [Fe(OH2)6]3+ and [FeCl(OH2)5]2+ were determined on the basis of the same EXAFS data. The F e -0 bond length (2.05 A) in the latter is longer than that (2.01 A) in the former due to the electron donation and charge neutralization by the coordinating chloride ion with the Fe-Cl bond length of 2.26 A. 
  Reference    Z. Naturforsch. 54b, 1517—1523 (1999); received August 23 1999 
  Published    1999 
  Keywords    EXAFS, Complexation, Formation Constant, Iron(III) Ion, Chloride Ion 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-1517.pdf 
 Identifier    ZNB-1999-54b-1517 
 Volume    54 
4Author    Kozo Shinoda, Eiichiro Matsubara, Masatoshi Saito, Yoshio Waseda, Tetsuji Hirato, Yasuhiro AwakuraRequires cookie*
 Title    Structural Study of Poly-Molybdate Ions in Acid Mo-Ni Aqueous Solutions  
 Abstract    The atomic structure of poly-molybdate ions formed in acid Ni-Mo aqueous solutions has been determined by applying anomalous X-ray scattering (AXS) and EXAFS methods. In a solution containing only molybdenum ions, we found only a poly-molybdate ion consisting of seven edge-sharing Mo0 6 octahedra. In a solution containing both Mo and Ni ions, there exists another poly-molybdate ion consisting of 6 edge-sharing MoO & surrounding an Ni ion. The total coordination number of Mo and Ni ions around a molybdenum ion is reduced by half when introducing citric ions into the Ni and Mo solution. This indicates that the large poly-molybdate ion is decomposed to smaller molybdate ions when forming citric complexes. Since molybdenum-nickel alloys can not be electrodeposited from solutions without citric ions, we propose a view that the structural change of the poly-molybdate ions in the solutions is closely related with the mechanism of induced codeposition of molybdenum and nickel alloy. The results of small-angle X-ray scattering (SAXS) measurements also support this conclusion. 
  Reference    Z. Naturforsch. 52a, 855—862 (1997); received November 10 1997 
  Published    1997 
  Keywords    Anomalous X-ray Scattering, EXAFS, Mo-Ni Alloy Electroplating, Aqueous Solution, Poly-molybdate Ion 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0855.pdf 
 Identifier    ZNA-1997-52a-0855 
 Volume    52