Anodic oxidation of UO2. V. Electrochemical and X-ray photoelectron spectroscopic studies of film-growth and dissolution in phosphate-containing solutions

1988 ◽  
Vol 66 (2) ◽  
pp. 259-265 ◽  
Author(s):  
D. W. Shoesmith ◽  
S. Sunder ◽  
M. G. Bailey ◽  
G. J. Wallace
Keyword(s):  
Anodic Oxidation ◽  
Film Growth ◽  
Surface Film ◽  
Spectroscopic Studies ◽  
Spectroscopic Techniques ◽  
X Ray ◽  
Rate Determining Step ◽  
Oxidation Potentials ◽  
Uranyl Phosphate ◽  
Yield Formula

The anodic oxidation of UO2 has been studied in aqueous phosphate solutions over the pH range 4 to 11, using a combination of electrochemical and X-ray photoelectron spectroscopic techniques. The early stages of oxidation, leading to the formation of a film of composition UO2.33, are unaffected by the presence of phosphate in the solutions. Phosphate concentrations [Formula: see text]prevent the formation of higher-oxide films that are present in phosphate-free solutions at higher oxidation potentials. Dissolution under steady-state conditions proceeds via a surface film of uranyl phosphate. For potentials [Formula: see text] (vs. SCE), the rate of dissolution to yield[Formula: see text] is controlled by charge-transfer kinetics. For potentials[Formula: see text], the rate-determining step is the chemical dissolution of the uranyl phosphate layer.

scholarly journals Pseudocapacitive Behavioral Testing of Iron Vanadate Nanoparticles Synthesized by Simple Co- Precipitation Method

2019 ◽  
Vol 9 (1S3) ◽  
pp. 374-378
Keyword(s):  
Electrochemical Impedance ◽  
Impedance Analysis ◽  
Spectroscopic Studies ◽  
Precipitation Method ◽  
Spectroscopic Techniques ◽  
Electron Microscopic ◽  
Electrochemical Behaviors ◽  
X Ray ◽  
Co Precipitation ◽  
Charge Discharge

Iron vanadate nanoparticles were prepared by simple co-precipitation method. The crystal structure and elemental composition of prepared material were confirmed using X-ray Diffraction analysis and Elemental Dispersive X- ray spectroscopic analysis respectively. Surface morphology of the sample was analyzed by Scanning Electron Microscopic techniques. Optical absorption and molecular vibrations were studied by UV-Vis. absorption spectroscopy and Fourier Transform Infrared spectroscopic techniques. Electrochemical behaviors such as redox property, charge-discharge mechanism and impedance analysis were examined with cyclic voltammetry, Galvanostatic charge-discharge and electrochemical impedance spectroscopic studies.

Molecular Composition and Orientation of Interstitial versus Surface Silicon Oxides for Si(111)/SiO2 and Si(100)/SiO2 Interfaces using FT-IR and X-ray Photoelectron Spectroscopies

2003 ◽  
Vol 57 (6) ◽  
pp. 628-635 ◽  
Author(s):  
Georgia Kandilioti ◽  
Angeliki Siokou ◽  
Vasiliki Papaefthimiou ◽  
Stella Kennou ◽  
Vasilis G. Gregoriou
Keyword(s):  
Thermal Oxidation ◽  
Photoelectron Spectroscopy ◽  
Silicon Oxide ◽  
Surface Film ◽  
Spectroscopic Studies ◽  
Native Oxide ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Ft Ir ◽  
On Chip

This work represents a characterization study of silicon oxide on Si(111) and Si(100) surfaces intended for use as substrates in organic light-emitting diodes (OLEDs) on chip devices. Samples have been prepared using either native oxide formation or thermal oxidation, and they have also been treated for activation of hydroxyl groups on their surface. Both Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used in order to understand the molecular orientation as well as the chemical composition of the various oxide types formed during these different oxidation processes. These spectroscopic studies reveal the formation of two different types of oxides on these substrates. The first type is a thin oxide layer on the surface, whereas the second type, called interstitial, is found deeper in the substrate. Specifically, it was found that the Si(100) substrate forms a randomly oriented interstitial oxide, whereas the presence of a lower quantity but more oriented interstitial oxide was found for the Si(111) substrate. In addition, we report for the first time the position of the impurity oxygen for Si(111) substrates at 1122 cm−1. Finally, in both Si(100) and Si(111) substrates, the thin (<15 Å) silicon oxide layers are oriented and appear to contain silicon atoms of similar oxidation states. In contrast, both the thicker surface film (100 Å) as well as the interstitial oxide produced by the thermal oxidation procedure show random orientation and relative uniformity. Overall these orientation studies clearly show that the formation process of surface oxides in different substrates clearly creates species that are oriented differently with respect to the surface.

ChemInform Abstract: Anodic Oxidation of U02. Part 1. Electrochemical and X-Ray Photoelectron Spectroscopic Studies in Neutral Solutions.

1982 ◽  
Vol 13 (12) ◽  
Author(s):  
S. SUNDER ◽  
D. W. SHOESMITH ◽  
M. G. BAILEY ◽  
F. W. STANCHELL ◽  
N. S. MCINTYRE
Keyword(s):  
Anodic Oxidation ◽  
Spectroscopic Studies ◽  
X Ray

X-Ray Spectroscopic Studies of Organo-Metallic Vapor Phase Epitaxial Growth

1993 ◽  
Vol 312 ◽  
Author(s):  
S. Brennant ◽  
P. H. Fuosst ◽  
D. W. Kisker ◽  
F. J. Lamelast ◽  
P. Imperatori ◽  
...  
Keyword(s):  
Film Growth ◽  
Chemical Vapor ◽  
Spectroscopic Studies ◽  
Reactor Vessel ◽  
X Rays ◽  
X Ray ◽  
Structural Probe ◽  
X Ray Absorption ◽  
Structural Probes ◽  
Metallic Vapor

AbstractChemical Vapor Deposition often occurs under conditions unsuitable for simultaneous monitoring using electron-based structural probes. This is due to the near-atmospheric pressure which exists during growth. While some work has been performed using optical probes, the typically high temperatures in the reactor vessel and the vastly longer wavelength of visible light versus the features being studied has hampered its utility as a structural probe. Over the past several years x-rays from synchrotron storage rings have been used to study the surface structure of growing materials. These studies have been primarily scattering studies. In this paper we explore the use of x-ray spectroscopic studies for the analysis of film growth. We have focused on three areas: the measurement of reactor vessel profiles using x-ray fluorescence; The measurement of gas-phase Extended X-ray Absorption Fine Structure (EXAFS), and the measurement of EXAFS of adsorbed species on the substrates.

scholarly journals X-ray Spectroscopies of High Energy Density Matter Created with X-ray Free Electron Lasers

2019 ◽  
Vol 9 (22) ◽  
pp. 4812 ◽  
Author(s):  
Byoung Ick Cho
Keyword(s):  
Energy Density ◽  
Free Electron ◽  
High Energy ◽  
Spectroscopic Studies ◽  
High Energy Density ◽  
Future Research ◽  
Spectroscopic Techniques ◽  
Free Electron Lasers ◽  
X Ray ◽  
Fundamental Properties

The recent progress in the development of X-ray free electron lasers (XFELs) allows for the delivery of over 1011 high-energy photons to solid-density samples in a femtosecond time scale. The corresponding peak brightness of XFEL induces a nonlinear response of matter in a short-wavelength regime. The absorption of an XFEL pulse in a solid also results in the creation of high energy density (HED) matter. The electronic structure and related fundamental properties of such HED matter can be investigated with the control of XFEL and various X-ray spectroscopic techniques. These experimental data provide unique opportunities to benchmark theories and models for extreme conditions and to guide further advances. In this article, the current progress in spectroscopic studies on intense XFEL–matter interactions and HED matter are reviewed, and future research opportunities are discussed.

Spectral investigations of meso-tetraalkylporphyrin-fullerene host–guest complexes

2015 ◽  
Vol 19 (09) ◽  
pp. 997-1006 ◽  
Author(s):  
Nitika Grover ◽  
Pinki Rathi ◽  
Muniappan Sankar
Keyword(s):  
Alkyl Chain ◽  
Supporting Electrolyte ◽  
Supramolecular Interactions ◽  
Spectroscopic Techniques ◽  
X Ray ◽  
Alkyl Chains ◽  
Oxidation Potentials ◽  
Donor Acceptor ◽  
Electrochemical Redox ◽  
Self Assembled

Meso-tetraalkylporphyrins and their Zn(II) complexes were synthesized and characterized by various spectroscopic techniques. Single crystal X-ray structure of meso-tetrapropylporphyrin (3) revealed the orientation of alkyl chains and planar conformation of porphyrin macrocycle. Spectroscopic, photophysical and electrochemical redox properties of self-assembled donor–acceptor dyads formed by meso-tetraalkylporphyrins and fullerene C 60 were investigated. These studies revealed 1:1 supramolecular dyad formation between the electron donor porphyrins and the electron acceptor, fullerene entities. The determined association constants (K) follow the order: H2TMeP (1) > H2TEtP (2) > H2TPrP (3) > H2THexP > H2TPP . The effect of alkyl chain length on porphyrin-fullerene complexation was investigated. The redox behavior of self-assembled dyads was investigated in PhCN containing 0.1 M TBAPF6 as supporting electrolyte. The oxidation potentials of dyads are positively shifted (20–100 mV) as compared to corresponding meso-tetraalkylporphyrins indicating the supramolecular interactions between the constituents in the ground state. The geometric and electronic structure of 1: C 60 was probed by DFT calculations which suggested the possibility of charge transfer from meso-tetraalkylporphyrin to fullerene C 60.

Structural Characterization of Gallbladder Stones Using Energy Dispersive X-ray Spectroscopy and X-ray Diffraction

2018 ◽  
Vol 21 (7) ◽  
pp. 495-500 ◽  
Author(s):  
Hassan A. Almarshad ◽  
Sayed M. Badawy ◽  
Abdalkarem F. Alsharari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Energy Dispersive ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Major Health Problem ◽  
X Ray ◽  
Gallbladder Stones ◽  
Pure Cholesterol ◽  
Scanning Electron

Aim and Objective: Formation of the gallbladder stones is a common disease and a major health problem. The present study aimed to identify the structures of the most common types of gallbladder stones using X-ray spectroscopic techniques, which provide information about the process of stone formation. Material and Method: Phase and elemental compositions of pure cholesterol and mixed gallstones removed from gallbladders of patients were studied using energy-dispersive X-ray spectroscopy combined with scanning electron microscopy analysis and X-ray diffraction. Results: The crystal structures of gallstones which coincide with standard patterns were confirmed by X-ray diffraction. Plate-like cholesterol crystals with laminar shaped and thin layered structures were clearly observed for gallstone of pure cholesterol by scanning electron microscopy; it also revealed different morphologies from mixed cholesterol stones. Elemental analysis of pure cholesterol and mixed gallstones using energy-dispersive X-ray spectroscopy confirmed the different formation processes of the different types of gallstones. Conclusion: The method of fast and reliable X-ray spectroscopic techniques has numerous advantages over the traditional chemical analysis and other analytical techniques. The results also revealed that the X-ray spectroscopy technique is a promising technique that can aid in understanding the pathogenesis of gallstone disease.

Gas Cell Infrared and Attenuated Total Reflection Infrared Spectroscopic Studies for Organic–Inorganic Interactions in Adsorption of Fulvic Acid on the Goethite Surface Generating Carbon Dioxide

2021 ◽  
pp. 000370282199121
Author(s):  
Yuki Nakaya ◽  
Satoru Nakashima ◽  
Takahiro Otsuka
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Fulvic Acid ◽  
Spectroscopic Studies ◽  
Reaction Model ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Gas Cell ◽  
Rate Determining Step ◽  
Ir Spectroscopic

The generation of carbon dioxide (CO2) from Nordic fulvic acid (FA) solution in the presence of goethite (α-FeOOH) was observed in FA–goethite interaction experiments at 25–80 ℃. CO2 generation processes observed by gas cell infrared (IR) spectroscopy indicated two steps: the zeroth order slower CO2 generation from FA solution commonly occurring in the heating experiments of the FA in the presence and absence of goethite (activation energy: 16–19 kJ mol–1), and the first order faster CO2 generation from FA solution with goethite (activation energy: 14 kJ mol–1). This CO2 generation from FA is possibly related to redox reactions between FA and goethite. In situ attenuated total reflection infrared (ATR-IR) spectroscopic measurements indicated rapid increases with time in IR bands due to COOH and COO– of FA on the goethite surface. These are considered to be due to adsorption of FA on the goethite surface possibly driven by electrostatic attraction between the positively charged goethite surface and negatively charged deprotonated carboxylates (COO–) in FA. Changes in concentration of the FA adsorbed on the goethite surface were well reproduced by the second order reaction model giving an activation energy around 13 kJ mol–1. This process was faster than the CO2 generation and was not its rate-determining step. The CO2 generation from FA solution with goethite is faster than the experimental thermal decoloration of stable structures of Nordic FA in our previous report possibly due to partial degradations of redox-sensitive labile structures in FA.

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