Using XANES to Monitor the Oxidation State of Cobalt Complexes

2007 ◽  
Vol 60 (3) ◽  
pp. 180 ◽  
Author(s):  
Matthew D. Hall ◽  
Clare K. Underwood ◽  
Timothy W. Failes ◽  
Garry J. Foran ◽  
Trevor W. Hambley
Keyword(s):  
Oxidation State ◽  
Cobalt Complexes ◽  
Reducing Agents ◽  
Oxidation States ◽  
Xanes Spectroscopy ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

X-Ray absorption near-edge structure (XANES) spectroscopy was used to monitor the oxidation state of cobalt following treatment of CoIII complexes with reducing agents such as ascorbate and cysteine. It was established that the XANES spectra of mixtures of CoII and CoIII complexes can be used to calculate proportions of the two oxidation states by monitoring the height of the Co K-edge. The relationships developed were used to estimate proportions of each complex in solutions of CoIII complexes treated with reducing agents.

Discrepancy in the quantitative oxidation-state analysis of Eu species in sulfide phosphors by K-, L1- and L3-edge XANES spectrometry: choice of absorption edge and measurement mode

2018 ◽  
Vol 33 (4) ◽  
pp. 585-592 ◽  
Author(s):  
Takashi Yamamoto ◽  
Akira Yukumoto
Keyword(s):  
Quantitative Analysis ◽  
Oxidation State ◽  
Absorption Edge ◽  
Oxidation States ◽  
Xanes Spectroscopy ◽  
Edge Structure ◽  
X Ray ◽  
Measurement Mode ◽  
Constituent Elements ◽  
X Ray Absorption

A quantitative analysis of the oxidation state of europium (Eu) in phosphor samples was performed using X-ray absorption near-edge structure (XANES) spectroscopy to investigate the influence of the constituent elements, absorption edge and measurement mode on the evaluated oxidation states.

Oxygen Reduction Effect on T’-Pr2-xCexCuO4 Nanopowders in the Underdoped Regime Studied by X-Ray Absorption near Edge Structure

2018 ◽  
Vol 936 ◽  
pp. 93-97 ◽  
Author(s):  
Irfanita Resky ◽  
Putu Eka Dharma Putra ◽  
Triono Bambang ◽  
Saiyasombat Chatree ◽  
Kamonsuangkasem Krongthong ◽  
...  
Keyword(s):  
Oxidation State ◽  
Oxidation States ◽  
Edge Structure ◽  
X Ray ◽  
Reduction Annealing ◽  
Gas Atmosphere ◽  
Reduction Effect ◽  
Ar Gas ◽  
X Ray Absorption ◽  
Cu Ions

This research is aimed to examine oxidation state of Copper (Cu) in both as-synthesized and reduced T’-Pr2-xCexCuO4 (T’-PCCO) with x = 0, 0.10, and 0.15 using Cu K-edge x-ray absorption near edge structure (XANES). The T‘-PCCO nanopowders were successfully synthesized by the chemically dissolved method with HNO3 as a dissolving agent continued by calcination at 1000°C for 15 h. The reduced T’-PCCO nanopowders were obtained by reduction annealing process at 700°C for 5 h under Ar gas atmosphere. The analyses of XANES spectra show that oxidation states of the Cu ions in all of the T'-PCCO nanopowders have values between +1 and +2. This indicates the existence of electron doping in the CuO2 planes, even in the undoped T’-structure. It is found that the oxidation states of the Cu ions change after reduction annealing depending on the existence of apical oxygen in the T'-structure. Based on the XANES analyses, it is revealed that the change of oxidation state is influenced by the presence of both electron and hole carriers in the two-carrier model of T’-structure.

Using X-ray absorption near edge structure (XANES) spectroscopy to determine selenium oxidation states in animal mineral supplements and feeds

2004 ◽  
Vol 84 (2) ◽  
pp. 171-175 ◽  
Author(s):  
C. R. Christensen ◽  
J. N. Cutler ◽  
D. A. Christensen
Keyword(s):  
Oxidation State ◽  
Animal Feed ◽  
Xanes Spectroscopy ◽  
Elemental Selenium ◽  
Selenium Speciation ◽  
Edge Structure ◽  
X Ray ◽  
Mineral Supplements ◽  
Animal Feeds ◽  
X Ray Absorption

Synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy is a relatively new technique within the life sciences. XANES has been utilized to identify the location, oxidation state and spatial distribution of heavy metal elements in plants , neurons, blood and DNA, but has not been widely used in the animal sciences. Selenium content in animal feeds is monitored, as both selenium deficiencies and toxicities are associated with physiological disorders. Selenium is available as an animal feed in both inorganic and organic states. The bioavailability of selenium species has been tested in numerous animal trials; however, a simple, non-destructive test for selenium speciation is not available. The objective of this study was to determine whether XANES spectroscopy could be used to determine the selenium oxidation state found in various commercial animal feed products. A comparison of absorption spectra indicated that the animal mineral supplements contained an organoselenium or selenite. The processed animal feeds had a spectral profile similar to that of elemental selenium. Further experiments are necessary to determine the implication of selenium speciation on animal physiology. Key words: Selenium speciation, mineral supplements, ruminants, non-ruminants, synchrotron, XANES, X-ray

scholarly journals A compact furnace for in situ X-ray absorption spectroscopy: design, fabrication and study of cationic oxidation states in Pr6O11 and NiO

2021 ◽  
Vol 28 (2) ◽  
pp. 455-460
Author(s):  
Suchinda Sattayaporn ◽  
Somboonsup Rodporn ◽  
Pinit Kidkhunthod ◽  
Narong Chanlek ◽  
Chutarat Yonchai ◽  
...  
Keyword(s):  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Heating Temperature ◽  
Reduction Process ◽  
Oxidation States ◽  
Quartz Tube ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

A well designed compact furnace has been designed for in situ X-ray absorption spectroscopy (XAS). It enables various heat ramps from 300 K to 1473 K. The furnace consists of heaters, a quartz tube, a circulated refrigerator and a power controller. It can generate ohmic heating via an induction process with tantalum filaments. The maximum heating rate exceeds 20 K min−1. A quartz tube with gas feedthroughs allows the mixing of gases and adjustment of the flow rate. The use of this compact furnace allows in situ XAS investigations to be carried out in transmission or fluorescence modes under controlled temperature and atmosphere. Moreover, the furnace is compact, light and well compatible to XAS. The furnace was used to study cationic oxidation states in Pr6O11 and NiO compounds under elevated temperature and reduced atmosphere using the in situ X-ray absorption near-edge structure (XANES) technique at beamline 5.2 SUT-NANOTEC-SLRI of the Synchrotron Light Research Institute, Thailand. At room temperature, Pr6O11 contains a mixture of Pr3+ and Pr4+ cations, resulting in an average oxidation state of +3.67. In situ XANES spectra of Pr (L 3-edge) show that the oxidation state of Pr4+ cations was totally reduced to +3.00 at 1273 K under H2 atmosphere. Considering NiO, Ni2+ species were present under ambient conditions. At 573 K, the reduction process of Ni2+ occurred. The Ni0/Ni2+ ratio increased linearly with respect to the heating temperature. Finally, the reduction process of Ni2+ was completely finished at 770 K.

scholarly journals An X-ray Absorption Near-Edge Structure (XANES) Study on the Oxidation State of Chromophores in Natural Kunzite Samples from Nuristan, Afghanistan

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 463
Author(s):  
Habib Ur Rehman ◽  
Gerhard Martens ◽  
Ying Lai Tsai ◽  
Chawalit Chankhantha ◽  
Pinit Kidkhunthod ◽  
...  
Keyword(s):  
Oxidation State ◽  
Inductively Coupled Plasma ◽  
Oxidation States ◽  
Transition Elements ◽  
Edge Structure ◽  
X Ray ◽  
Inductively Coupled ◽  
Valence States ◽  
Icp Ms ◽  
X Ray Absorption

Kunzite, the pink variety of spodumene is famous and desirable among gemstone lovers. Due to its tenebrescent properties, kunzite always remains a hot research candidate among physicists and mineralogists. The present work is continuing the effort towards value addition to kunzite by enhancing its color using different treatments. Before color enhancement, it is essential to identify the chromophores and their oxidation states. In this paper, the authors investigated the main impurities in natural kunzite from the Nuristan area in Afghanistan and their valence states. Some impurities in the LiAlSi2O6 spodumene structure were identified and quantified by using sensitive techniques, including Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), UV−VIS and X-ray absorption near-edge structure (XANES). LA-ICP-MS indicated many trace elements as impurities in kunzite, among which Fe and Mn are the main elements responsible for coloration. The oxidation states of these two transition elements were determined by the XANES technique. The study reveals that Mn is present in both Mn2+ and Mn3+ oxidation states, while Fe is present only in Fe3+ oxidation state.

XANES of chromium in sludges used as soil ameliorants

2003 ◽  
Vol 81 (2) ◽  
pp. 193-196 ◽  
Author(s):  
R R Martin ◽  
S J Naftel ◽  
T K Sham ◽  
B Hart ◽  
M A Powell
Keyword(s):  
Oxidation State ◽  
Chromium Content ◽  
Xanes Spectroscopy ◽  
Sewage Sludges ◽  
Edge Structure ◽  
Aqua Regia ◽  
X Ray ◽  
X Ray Absorption

Samples of sewage sludges proposed for use as soil ameliorants in an Indo-Canadian project were tested for chromium content. Standard aqua regia extractions found one sludge to have excessive amounts of Cr. X-ray absorption near-edge structure (XANES) spectroscopy, however, indicated that the Cr was present in the relatively benign Cr(III) oxidation state in all the sludge samples.Key words: soil, chromium, synchrotron, XANES.

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