X-ray Absorption near Edge Structure and Crystallographic Studies of the Mixed Valence Oxides CaRu1−xMnxO3

2009 ◽  
Vol 21 (18) ◽  
pp. 4203-4209 ◽  
Author(s):  
Qingdi Zhou ◽  
Brendan J. Kennedy ◽  
Zhaoming Zhang ◽  
Ling-Yun Jang ◽  
Jade B. Aitken
Keyword(s):  
Mixed Valence ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

ChemInform Abstract: X-Ray Absorption Near Edge Structure and Crystallographic Studies of the Mixed Valence Oxides CaRu1-xMnxO3.

ChemInform ◽  
2009 ◽  
Vol 40 (49) ◽  
Author(s):  
Qingdi Zhou ◽  
Brendan J. Kennedy ◽  
Zhaoming Zhang ◽  
Ling-Yun Jang ◽  
Jade B. Aitken
Keyword(s):  
Mixed Valence ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

Manganese speciation in soils using X-ray absorption spectroscopy

2020 ◽  
Author(s):  
Teresa Zahoransky ◽  
Christian Mikutta
Keyword(s):  
Absorption Spectroscopy ◽  
Chemical Reactivity ◽  
Mixed Valence ◽  
Oxidation States ◽  
Plant Residues ◽  
Edge Structure ◽  
Coordination Environment ◽  
X Ray ◽  
Local Coordination ◽  
X Ray Absorption

<p>Being one of Earth´s most redox-active elements, manganese participates in a great variety of environmental processes and is recognized as a key player controlling carbon turnover and oxidative transformation of organic and inorganic pollutants in soils. Moreover, Mn(III), Mn(IV) or mixed-valence Mn(III/IV) oxides and (oxy)hydroxides are highly effective sorbents for metal pollutants and nutrients in soils. Chemical reactivity, mobility, and bioavailability of Mn depend crucially on its speciation (chemical form). Yet, speciation studies on soil Mn are scarce. Therefore, we employed Mn K-edge (6,539 eV) X-ray absorption spectroscopy (XAS) to determine the oxidation states and local coordination environment (<5 Å) of Mn in oxic bulk soils (Cambisols, Luvisols, Stagnosol) from various field sites in Germany. Our XAS analyses cover 23 soil L, O, A, B, and C horizons exhibiting total Mn concentrations of between 200 and 2,300 mg/kg. For comparison, we also analyze a suite of 31 Mn reference compounds, including Mn carbonate, phosphate, oxides and (oxy)hydroxides, silicates, organic Mn compounds as well as clay and hydroxide minerals with adsorbed Mn(II). X-ray absorption near-edge structure (XANES) spectra are evaluated for the oxidation states of soil Mn using linear combination fit (LCF) analysis. In addition, the average local coordination environment of Mn in the soil samples is assessed by shell-fitting of extended X-ray absorption fine structure (EXAFS) spectra. Based on our XAS results, we will test the following hypotheses: (1) Soil L/O horizons comprise predominantly organically complexed Mn(II) and Mn(III), dominated by the former Mn species; (2) soil A horizons are dominated by Mn(III/IV) in Mn(III/IV)-oxide structures owing to high microbial activity, release of Mn(II) from primary silicates and/or plant residues, and its subsequent (a)biotic oxidation and precipitation as Mn(III/IV) oxides; (3) soil B horizons of different genesis differ in their bulk Mn speciation; Bt horizons of Luvisols are dominated by Mn(II) associated with phyllosilicates, whereas the Stagnosol Bg horizon is dominated by layer-type Mn(III/IV) oxides. In summary, our study will provide first comprehensive data on bulk Mn speciation in three major European soil types. This knowledge is a prerequisite for a better understanding of the biogeochemical Mn cycle in soils.</p>

X-ray absorption near edge structure and crystallographic studies of the mixed valence oxide SrRu0.8Ni0.2O3

2011 ◽  
Vol 23 (43) ◽  
pp. 435401 ◽  
Author(s):  
Ilyas Qasim ◽  
Brendan J Kennedy ◽  
Zhaoming Zhang ◽  
Maxim Avdeev ◽  
Ling-Yun Jang
Keyword(s):  
Mixed Valence ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

X-ray-absorption near-edge-structure study ofEuPd3Bx: A mixed-valence system

1984 ◽  
Vol 30 (7) ◽  
pp. 4031-4033 ◽  
Author(s):  
B. Darshan ◽  
B. D. Padalia ◽  
R. Nagarajan ◽  
S. K. Dhar ◽  
S. K. Malik ◽  
...  
Keyword(s):  
Mixed Valence ◽  
Structure Study ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

Chemical and orientational imaging of polymeric samples

1994 ◽  
Vol 52 ◽  
pp. 68-69
Author(s):  
H. Ade ◽  
B. Hsiao ◽  
G. Mitchell ◽  
E. Rightor ◽  
A. P. Smith ◽  
...  
Keyword(s):  
Ethylene Terephthalate ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Carbonyl Groups ◽  
Aromatic Rings ◽  
Edge Structure ◽  
X Ray ◽  
Scanning Transmission ◽  
Polymeric Samples ◽  
X Ray Absorption

We have used the Scanning Transmission X-ray Microscope at beamline X1A (X1-STXM) at Brookhaven National Laboratory (BNL) to acquire high resolution, chemical and orientation sensitive images of polymeric samples as well as point spectra from 0.1 μm areas. This sensitivity is achieved by exploiting the X-ray Absorption Near Edge Structure (XANES) of the carbon K edge. One of the most illustrative example of the chemical sensitivity achievable is provided by images of a polycarbonate/pol(ethylene terephthalate) (70/30 PC/PET) blend. Contrast reversal at high overall contrast is observed between images acquired at 285.36 and 285.69 eV (Fig. 1). Contrast in these images is achieved by exploring subtle differences between resonances associated with the π bonds (sp hybridization) of the aromatic groups of each polymer. PET has a split peak associated with these aromatic groups, due to the proximity of its carbonyl groups to its aromatic rings, whereas PC has only a single peak.

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