Temperature and Light-Induced Structural Changes in Photosynthetic Reaction Center Proteins Probed by X-ray Absorption Fine Structure

2004 ◽  
Vol 108 (12) ◽  
pp. 3912-3924 ◽  
Author(s):  
Lin X. Chen ◽  
Lisa M. Utschig ◽  
Sandra L. Schlesselman ◽  
David M. Tiede
Keyword(s):  
Fine Structure ◽  
Reaction Center ◽  
Structural Changes ◽  
Photosynthetic Reaction Center ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

scholarly journals Structural Change Analysis of Cerianite in Weathered Residual Rare Earth Ore by Mechanochemical Reduction Using X-Ray Absorption Fine Structure

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 267 ◽  
Author(s):  
Tatsuya Kato ◽  
Yuki Tsunazawa ◽  
Wenying Liu ◽  
Chiharu Tokoro
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Structural Change ◽  
Oxygen Vacancy ◽  
Structural Changes ◽  
Mechanochemical Reaction ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Mechanochemical Reactions

Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. The mechanism of mechanochemical reaction has been investigated using solid analyses and simulations. Structural changes caused by mechanochemical reactions are not yet sufficiently clarified because the ground samples are amorphous. The objective of this study was to analyze structural changes of cerianite in weathered residual rare earth ore by mechanochemical reduction. The ore was ground by planetary ball milling for 10, 60 and 720 min. Structural change was analyzed by the X-ray absorption near-edge structure and extended x-ray absorption fine structure analysis at the cerium LIII- and K-edges. These analyses revealed that the structural change of cerianite in this ore induced by mechanochemical reduction involved oxygen vacancy production. The process of the oxygen vacancy formation was closely coupled with the quantum effect of localization–delocalization of the 4f electron of cerium.

Structural determinations of liquid semiconductors using extended X-ray absorption fine structure

1977 ◽  
Vol 55 (11) ◽  
pp. 1968-1974 ◽  
Author(s):  
E. D. Crozier ◽  
F. W. Lytle ◽  
D. E. Sayers ◽  
E. A. Stern
Keyword(s):  
Fine Structure ◽  
Disordered Systems ◽  
Structural Changes ◽  
Structural Information ◽  
Structural Rearrangement ◽  
Nearest Neighbour ◽  
X Ray ◽  
Absorption Fine ◽  
Amorphous States ◽  
X Ray Absorption

The extended fine structure in the X-ray absorption coefficient is dominated by the interference of the photoelectron scattered by atoms in the immediate neighbourhood of the atom which absorbs the X-ray photon and thus can provide structural information about ordered or disordered systems. In this paper it is demonstrated that Extended X-Ray Absorption Fine Structure (EXAFS) measurements can be made on liquid systems at high temperatures. The technique is illustrated with results for As2Se3 in the liquid and amorphous states for temperatures between 100 and 773 K. A Fourier analysis of the EXAFS data reveals that a major structural rearrangement does not occur in the nearest neighbour shell when As2Se3 is melted. However, small structural changes do occur at the melting point which, within the limitations of the present data, suggest a slight increase in the nearest neighbour As–Se distance, a decrease in the number of nearest neighbours, and a decrease in the nearest neighbour disorder term σ12.

scholarly journals Structural Change Analysis of Cerianite in Weathered Residual Rare Earth Ore by Mechanochemical Reduction Using X-ray Absorption Fine Structure

2019 ◽  
Author(s):  
Tatsuya Kato ◽  
Yuki Tsunazawa ◽  
Wenying Liu ◽  
Chiharu Tokoro
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Structural Change ◽  
Oxygen Vacancy ◽  
Structural Changes ◽  
Mechanochemical Reaction ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. The mechanism of mechanochemical reaction has been investigated using solid analyses and simulations. Structural changes caused by mechanochemical reaction are not yet sufficiently clarified because the ground samples are amorphous. The objective of this study was to analyze structural changes of cerianite in weathered residual rare earth ore by mechanochemical reduction. Structural change was analyzed by x-ray absorption near-edge structure and extended x-ray absorption fine structure analysis at the cerium LIII- and K-edges. These analyses revealed that the structural change of cerianite in this ore induced by mechanochemical reduction involved oxygen vacancy production. The process of the oxygen vacancy formation was closely coupled with the quantum effect of localization–delocalization of the 4f electron of cerium.

Structural changes on annealing of MBE grown (Ga, In)(N, As) as measured by X-ray absorption fine structure

2003 ◽  
Vol 251 (1-4) ◽  
pp. 408-411 ◽  
Author(s):  
Vincent Gambin ◽  
Vincenzo Lordi ◽  
Wonill Ha ◽  
Mark Wistey ◽  
Toshiyuki Takizawa ◽  
...  
Keyword(s):  
Fine Structure ◽  
Structural Changes ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Structure of Prototypical Semiconductor Surfaces and Interfaces Investigated by Photoemission Extended X-Ray Absorption Fine Structure (PEXAFS)

1998 ◽  
Vol 05 (05) ◽  
pp. 1057-1086 ◽  
Author(s):  
P. S. Mangat ◽  
P. Soukiassian
Keyword(s):  
Fine Structure ◽  
Alkali Metals ◽  
Structural Changes ◽  
Core Level ◽  
Level Shift ◽  
Semiconductor Surfaces ◽  
X Ray ◽  
Absorption Fine ◽  
Surfaces And Interfaces ◽  
X Ray Absorption

Extended X-ray absorption fine structure (EXAFS) has been known for half a century. However, using synchrotron radiation, it has developed into a powerful tool for determining the atomic structure of a wide variety of surfaces and interfaces. The power of this technique lies in its sensitivity to the local environment of a particular element. Photoemission extended X-ray absorption fine structure (PEXAFS) is a new variation of electron detection surface EXAFS (SEXAFS) using photoemission spectroscopy in the constant initial state mode, Due to small escape depths, a very high surface sensitivity is achieved. Other major advantages of this new technique include (i) an improved signal/noise ratio allowing very short data collection times, which is an especially useful feature for short lifetime surfaces, and (ii) double-checking interatomic distances. Combined with core level and valence band photoemission spectroscopies. PEXAFS provides the exceptional ability to probe the atomic geometry and the electronic structure at the same time and for the same surface. It thus gives access to important issues, such as (i) surface reconstruction and/or relaxation, (ii) bonding nature, (iii) adsorption site and (iv) initial interface formation. Furthermore, it could be used to clarify photoemission core level shift origin by allowing one to discriminate structural changes from other causes as initial or final state effects. This article reviews the latest PEXAFS investigations for model elemental (silicon) and compound (indium phosphide) semiconductor surfaces and their interfaces with alkali metals, antimony, aluminum, bismuth and silver.

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