Synchrotron X-ray Absorption Spectroscopy Studies of Pt/Si Systems

1998 ◽  
Vol 524 ◽  
Author(s):  
I. Coulthard ◽  
S. J. Naftel ◽  
T. K. Shama
Keyword(s):  
Porous Silicon ◽  
Absorption Spectroscopy ◽  
Silicon Substrate ◽  
Reducing Power ◽  
Deposition Technique ◽  
Edge Structure ◽  
X Ray ◽  
Porous Silicon Substrate ◽  
Spectroscopy Studies ◽  
X Ray Absorption

ABSTRACTPlatinum was deposited onto porous silicon by a reductive deposition technique utilizing the inherent reducing power of porous silicon. The resulting deposits were studied by X-ray Absorption Near Edge Structure (XANES) at the Si-K, Pt-M3, 2, and Pt-L 3 ,2 edges. Samples of varying deposition concentrations were studied and were compared with untreated porous silicon and platinum silicides to determine the nature of the deposits and their effect upon the porous silicon substrate itself.

X-ray absorption spectroscopy studies for the determination of adsorption binding modes of selenium oxoanions onto iron and manganese based nanomaterials

2012 ◽  
Vol 1480 ◽  
Author(s):  
Christina M. Gonzalez ◽  
Jason G. Parsons ◽  
Jeffrey Hernandez ◽  
Jorge L. Gardea-Torresdey
Keyword(s):  
Absorption Spectroscopy ◽  
Binding Modes ◽  
Edge Structure ◽  
X Ray ◽  
Microwave Assisted ◽  
Spectroscopy Studies ◽  
X Ray Absorption ◽  
Binding Mechanisms ◽  
Iron And Manganese

ABSTRACTIncreasing concentrations of selenium oxoanions in the environment are placing many animals at risk for reproduction failure and deformities. The understanding of binding mechanisms of selenium oxoanions to iron and manganese based oxide minerals could lead to enhanced understanding of selenium mobility in the environment. In this study, the binding mechanisms of selenium oxoanions, selenite and selenate, to non microwave-assisted and microwave-assisted synthetic Fe3O4, Mn3O4, and MnFe2O4 nanomaterials were investigated through the use of X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) spectroscopy studies revealed the oxidation state of selenite and selenate remains the same after binding occurs to all nanomaterials in pH 2, 4, or 6 environments. The binding modes of selenite and selenate were determined to be bidentate binuclear through use of Extended x-ray absorption fine structure (EXAFS) and were independent of nanomaterials, synthetic technique, and pH.

scholarly journals In Situ X-ray Absorption Spectroscopy Studies of Discharge Reactions in a Thick Cathode of a Lithium Sulfur Battery

2016 ◽  
Vol 164 (2) ◽  
pp. A18-A27 ◽  
Author(s):  
Kevin H. Wujcik ◽  
Dunyang Rita Wang ◽  
Tod A. Pascal ◽  
David Prendergast ◽  
Nitash P. Balsara
Keyword(s):  
Absorption Spectroscopy ◽  
X Ray ◽  
Lithium Sulfur Battery ◽  
Spectroscopy Studies ◽  
Sulfur Battery ◽  
X Ray Absorption ◽  
Lithium Sulfur

scholarly journals Effects of ZnO nanoparticles in alfalfa, tomato, and cucumber at the germination stage: Root development and X-ray absorption spectroscopy studies

2013 ◽  
Vol 85 (12) ◽  
pp. 2161-2174 ◽  
Author(s):  
Guadalupe de la Rosa ◽  
Martha Laura López-Moreno ◽  
David de Haro ◽  
Cristian E. Botez ◽  
José R. Peralta-Videa ◽  
...  
Keyword(s):  
Seed Germination ◽  
Absorption Spectroscopy ◽  
Root Elongation ◽  
Dry Weight ◽  
Zno Nps ◽  
X Ray ◽  
Zn Content ◽  
Spectroscopy Studies ◽  
X Ray Absorption ◽  
Germination Stage

Past reports indicate that some nanoparticles (NPs) affect seed germination; however, the biotransformation of metal NPs is still not well understood. This study investigated the toxicity on seed germination/root elongation and the uptake of ZnO NPs and Zn2+ in alfalfa (Medicago sativa), cucumber (Cucumis sativus), and tomato (Solanum lycopersicum) seedlings. Seeds were treated with ZnO NPs at 0–1600 mg L–1 as well as 0–250 mg L–1 Zn2+ for comparison purposes. Results showed that at 1600 mg L–1 ZnO NPs, germination in cucumber increased by 10 %, and alfalfa and tomato germination were reduced by 40 and 20 %, respectively. At 250 mg Zn2+ L–1, only tomato germination was reduced with respect to controls. The highest Zn content was of 4700 and 3500 mg kg–1 dry weight (DW), for alfalfa seedlings germinated in 1600 mg L–1 ZnO NPs and 250 mg L–1 Zn2+, respectively. Bulk X-ray absorption spectroscopy (XAS) results indicated that ZnO NPs were probably biotransformed by plants. The edge energy positions of NP-treated samples were at the same position as Zn(NO3)2, which indicated that Zn in all plant species was as Zn(II).

X-ray absorption spectroscopy and density functional analysis of the Fe3+ distribution profile on Al sites in a chrysoberyl crystal, BeAl2O4:Fe3+

2016 ◽  
Vol 49 (2) ◽  
pp. 385-388 ◽  
Author(s):  
Kanokwan Kanchiang ◽  
Atipong Bootchanont ◽  
Janyaporn Witthayarat ◽  
Sittichain Pramchu ◽  
Panjawan Thanasuthipitak ◽  
...  
Keyword(s):  
Optical Properties ◽  
Absorption Spectroscopy ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Distribution Profile ◽  
Laser Applications ◽  
Edge Structure ◽  
X Ray ◽  
Site Distribution ◽  
X Ray Absorption

Chrysoberyl is one of the most interesting minerals for laser applications, widely used for medical purposes, as it exhibits higher laser performance than other materials. Although its utilization has been vastly expanded, the location of transition metal impurities, especially the iron that is responsible for chrysoberyl's special optical properties, is not completely understood. The full understanding and control of these optical properties necessitates knowledge of the precise location of the transition metals inside the structure. Therefore, synchrotron X-ray absorption spectroscopy (XAS), a local structural probe sensitive to the different local geometries, was employed in this work to determine the site occupation of the Fe3+ cation in the chrysoberyl structure. An Fe K-edge X-ray absorption near-edge structure (XANES) simulation was performed in combination with density functional theory calculations of Fe3+ cations located at different locations in the chrysoberyl structure. The simulated spectra were then qualitatively compared with the measured XANES features. The comparison indicates that Fe3+ is substituted on the two different Al2+ octahedral sites with the proportion 60% on the inversion site and 40% on the reflection site. The accurate site distribution of Fe3+ obtained from this work provides useful information on the doping process for improving the efficiency of chrysoberyl as a solid-state laser material.

In Situ X-Ray Absorption Spectroscopy Studies of Carbon Monoxide Oxidation in the Presence of Nanocomposite Cu–Fe–Al Oxide Catalysts

2021 ◽  
Vol 62 (1) ◽  
pp. 160-171
Author(s):  
A. M. Kremneva ◽  
A. V. Fedorov ◽  
A. A. Saraev ◽  
O. A. Bulavchenko ◽  
V. A. Yakovlev ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Absorption Spectroscopy ◽  
Carbon Monoxide Oxidation ◽  
Oxide Catalysts ◽  
X Ray ◽  
Spectroscopy Studies ◽  
X Ray Absorption ◽  
Al Oxide

In situ X-ray absorption spectroscopy studies of Pt-mordenite catalysts

1995 ◽  
Vol 208-209 ◽  
pp. 651-652 ◽  
Author(s):  
Mark M. Otten ◽  
Scott N. Reifsnyder ◽  
H.Henry Lamb
Keyword(s):  
Absorption Spectroscopy ◽  
X Ray ◽  
Spectroscopy Studies ◽  
X Ray Absorption
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