Probing the local coordination environment and nuclearity of uranyl(vi) complexes in non-aqueous media by emission spectroscopy

2011 ◽  
Vol 40 (15) ◽  
pp. 3914 ◽  
Author(s):  
Michael P. Redmond ◽  
Stephanie M. Cornet ◽  
Sean D. Woodall ◽  
Daniel Whittaker ◽  
David Collison ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Aqueous Media ◽  
Coordination Environment ◽  
Local Coordination

scholarly journals Modulating the local coordination environment of single-atom catalysts for enhanced catalytic performance

Nano Research ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1842-1855 ◽  
Author(s):  
Xinyuan Li ◽  
Hongpan Rong ◽  
Jiatao Zhang ◽  
Dingsheng Wang ◽  
Yadong Li
Keyword(s):  
Catalytic Performance ◽  
Single Atom ◽  
Coordination Environment ◽  
Local Coordination

Probing the influence of local coordination environment on ligand binding in nickel hydrogenase model complexes

1993 ◽  
Vol 32 (25) ◽  
pp. 5868-5877 ◽  
Author(s):  
Mikyung Cha ◽  
Christine L. Gatlin ◽  
Susan C. Critchlow ◽  
Julie A. Kovacs
Keyword(s):  
Ligand Binding ◽  
Model Complexes ◽  
Coordination Environment ◽  
Local Coordination

Substrate and co-catalyst effects on the local coordination environment of a Fe–porphyrin catalyst

2010 ◽  
Vol 494 (4-6) ◽  
pp. 289-294 ◽  
Author(s):  
Konstantinos C. Christoforidis ◽  
Maria Louloudi ◽  
Yiannis Deligiannakis
Keyword(s):  
Co Catalyst ◽  
Coordination Environment ◽  
Local Coordination

scholarly journals Aqueous Solutions of Uranium(VI) as Studied by Time-Resolved Emission Spectroscopy: A Round-Robin Test

2003 ◽  
Vol 57 (8) ◽  
pp. 1027-1038 ◽  
Author(s):  
Isabelle Billard ◽  
Eric Ansoborlo ◽  
Kathleen Apperson ◽  
Sylvie Arpigny ◽  
M. Emilia Azenha ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Emission Spectroscopy ◽  
Spectral Band ◽  
Aqueous Media ◽  
Round Robin ◽  
Fluoride Ions ◽  
Time Resolved ◽  
Sulfate Ions ◽  
Speciation Diagrams ◽  
Emitting Species

Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO22+aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

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>

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