ZfN: Search Results

1	Author	Hiroyuki Ishida, Hironobu Maeda, Akiko Hirano, Tamotsu Fujimoto, Yoshihiro Kubozono, Setsuo Kashino, Shuichi Emura	Requires 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

2	Author	J. M. Ramallo-López, F. G. Requejo, A. G. Bibiloni, M. Rentería, L. Gutierrez, E. E. Miró	Requires 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

3	Author	Yasuhiro Inada3, Shigenobu Funahashib	Requires 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

4	Author	Kozo Shinoda, Eiichiro Matsubara, Masatoshi Saito, Yoshio Waseda, Tetsuji Hirato, Yasuhiro Awakura	Requires 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