X-Ray Absorption Spectroscopy of Nitrogenase Mo-Fe Protein

1993 ◽  
Vol 307 ◽  
Author(s):  
J. Chen ◽  
J. Christiansen ◽  
S. George ◽  
R. Tittsworth ◽  
B. Hales ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Electronic Structures ◽  
Exafs Data ◽  
X Ray ◽  
Fe Protein ◽  
First Time ◽  
X Ray Absorption

ABSTRACTWe have studied both the atomic and electronic structures of nitrogenase Mo-Fe proteins using EXAFS and L-edge spectroscopy. The Mo and Fe K-edge EXAFS data show not only 2.37, 2.70, 2.29, and 2.63 Å first shell Mo-S, Mo-Fe, Fe-S, and Fe-Fe distances, but also 3.8, 4.3 and 5.1 Å second shell Fe-Fe, Fe-S, and Mo-Fe interactions. These observed distances are consistent with recent crystallographic models for the M-center. The average Mcenter distances have been defined with unprecedented accuracy. The nitrogenase Fe L-edge spectra have been obtained for the first time, and the result suggests that the Fe exists in both Fe2+ and Fe3+ states.

Electronic structures of Ba1-xCaxTiO3studied by x-ray absorption spectroscopy and theoretical calculation

2001 ◽  
Vol 13 (48) ◽  
pp. 11087-11095 ◽  
Author(s):  
K Asokan ◽  
J C Jan ◽  
J W Chiou ◽  
W F Pong ◽  
M-H Tsai ◽  
...  
Keyword(s):  
Theoretical Calculation ◽  
Absorption Spectroscopy ◽  
Electronic Structures ◽  
X Ray ◽  
X Ray Absorption

ELECTRONIC STRUCTURES OF La0.7Ca0.3MnO3 AND La0.7Ce0.3MnO3 BY X-RAY ABSORPTION SPECTROSCOPY

2002 ◽  
Vol 09 (02) ◽  
pp. 1053-1057 ◽  
Author(s):  
K. ASOKAN ◽  
K. V. R. RAO ◽  
J. C. JAN ◽  
J. W. CHIOU ◽  
W. F. PONG ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Electronic Structures ◽  
Spectral Features ◽  
Electron Hole ◽  
Edge Structure ◽  
X Ray ◽  
Strong Hybridization ◽  
Doped Manganites ◽  
X Ray Absorption ◽  
Tetravalent State

Electronic structures of hole-doped and electron hole-doped manganites, La 0.7 Ca 0.3 MnO 3 and La 0.7 Ce 0.3 MnO 3, have been elucidated by X-ray absorption near-edge structure (XANES) spectra of O K- and Mn L3,2-edges. In the electron-doped system, La 0.7 Ce 0.3 MnO 3, the spectral features of O K-edge spectra are shifted by ~ 1 eV towards the higher energy side and reduction of Mn valency from 4+ and 3+ to 3+ and 2+ is expected when compared to hole-doped manganite. The XANES of Ce M5,4-edges indicates a tetravalent state for Ce, similar to that in CeO 2. Ce 4+ is incorporated into the lattice of LaMnO 3, resulting in the modification of MnO 6 octahedra and also indicating strong hybridization of Ce 5d and/or Ce 4f states with O 2p states.

Comparison of electronic structures of orthorhombic and hexagonal manganites studied by X-ray absorption spectroscopy

2005 ◽  
Vol 134 (12) ◽  
pp. 821-826 ◽  
Author(s):  
K. Asokan ◽  
C.L. Dong ◽  
C.W. Bao ◽  
H.M. Tsai ◽  
J.W. Chiou ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Electronic Structures ◽  
X Ray ◽  
Hexagonal Manganites ◽  
X Ray Absorption

Electronic structures of silicon monoxide film probed by X-ray absorption spectroscopy

2013 ◽  
Vol 612 ◽  
pp. 77-81 ◽  
Author(s):  
Yuji Baba ◽  
Tetsuhiro Sekiguchi ◽  
Iwao Shimoyama ◽  
Norie Hirao
Keyword(s):  
Absorption Spectroscopy ◽  
Electronic Structures ◽  
Silicon Monoxide ◽  
X Ray ◽  
X Ray Absorption

Study of MgXZn1-XO Alloys (0

2013 ◽  
Vol 663 ◽  
pp. 361-365 ◽  
Author(s):  
Wei Zheng ◽  
Zhe Chuan Feng ◽  
Fan Hsiu Chang ◽  
Jyh Fu Lee ◽  
Rui Sheng Zheng ◽  
...  
Keyword(s):  
Fine Structure ◽  
High Resolution ◽  
Detailed Analysis ◽  
Absorption Spectroscopy ◽  
Electronic Structures ◽  
Chemical Bonds ◽  
Absorption Data ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

High-resolution K-edge x-ray absorption data are presented for Mg, Zn and O of Mg1-xZnxO films. A detailed analysis of the extended x-ray absorption fine structure by using the IFEFFIT program is given, and the Zn form chemical bonds with O are obtained. The x-ray absorption near-edge structure of Mg, Zn and O K-edge are investigated, and the electronic structures of Mg1-xZnxO with various compositions are studied.

scholarly journals A soft molecular 2Fe–2As precursor approach to the synthesis of nanostructured FeAs for efficient electrocatalytic water oxidation

2020 ◽  
Vol 11 (43) ◽  
pp. 11834-11842
Author(s):  
Rodrigo Beltrán-Suito ◽  
Viktoria Forstner ◽  
J. Niklas Hausmann ◽  
Stefan Mebs ◽  
Johannes Schmidt ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Water Oxidation ◽  
Ex Situ ◽  
X Ray ◽  
Active Structure ◽  
First Time ◽  
X Ray Absorption

A molecularly derived FeAs has been used as an electro(pre)catalyst for an efficient alkaline OER for the first time and subsequently, its active structure has been determined by quasi in situ X-ray absorption spectroscopy and ex situ methods.

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