Detection of sulphur and polysulphides on electrochemically oxidized pyrite surfaces by X-ray photoelectron spectroscopy and Raman spectroscopy

1990 ◽  
Vol 292 (1-2) ◽  
pp. 139-152 ◽  
Author(s):  
J.R. Mycroft ◽  
G.M. Bancroft ◽  
N.S. McIntyre ◽  
J.W. Lorimer ◽  
I.R. Hill
Keyword(s):  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
X Ray

scholarly journals Increased Electrical Conductivity of Carbon Nanotube Fibers by Thermal and Voltage Annealing

2021 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
Varun Shenoy Gangoli ◽  
Chris J. Barnett ◽  
James D. McGettrick ◽  
Alvin Orbaek White ◽  
Andrew R. Barron
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Separate Analysis ◽  
Sweet Spot ◽  
Electrical Conductor ◽  
X Ray ◽  
Resonant Raman ◽  
Carbon Nanotube Fibers

We report the effect of annealing, both electrical and by applied voltage, on the electrical conductivity of fibers spun from carbon nanotubes (CNTs). Commercial CNT fibers were used as part of a larger goal to better understand the factors that go into making a better electrical conductor from CNT fibers. A study of thermal annealing in a vacuum up to 800 °C was performed on smaller fiber sections along with a separate analysis of voltage annealing up to 7 VDC; both exhibited a sweet spot in the process as determined by a combination of a two-point probe measurement with a nanoprobe, resonant Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scaled-up tests were then performed in order to translate these results into bulk samples inside a tube furnace, with similar results that indicate the potential for an optimized method of achieving a better conductor sample made from CNT fibers. The results also help to determine the surface effects that need to be overcome in order to achieve this.

scholarly journals Photocatalytic activity of graphene oxide–TiO 2 thin films sensitized by natural dyes extracted from Bactris guineensis

2019 ◽  
Vol 6 (3) ◽  
pp. 181824 ◽  
Author(s):  
William Vallejo ◽  
Angie Rueda ◽  
Carlos Díaz-Uribe ◽  
Carlos Grande ◽  
Patricia Quintana
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
Photocatalytic Degradation ◽  
Photoelectron Spectroscopy ◽  
Chemical Characterization ◽  
Sem Analysis ◽  
Visible Range ◽  
X Ray ◽  
Natural Sensitizer

This study synthesized and characterized composites of graphene oxide and TiO 2 (GO–TiO 2 ). GO–TiO 2 thin films were deposited using the doctor blade technique. Subsequently, the thin films were sensitized with a natural dye extracted from a Colombian source ( Bactris guineensis ). Thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements were used for physico-chemical characterization. All the samples were polycrystalline in nature, and the diffraction signals corresponded to the TiO 2 anatase crystalline phase. Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) verified the synthesis of composite thin films, and the SEM analysis confirmed the TiO 2 films morphological modification after the process of GO incorporation and sensitization. XPS results suggested a possibility of appearance of titanium (III) through the formation of oxygen vacancies (O v ). Furthermore, the optical results indicated that the presence of the natural sensitizer and GO improved the optical properties of TiO 2 in the visible range. Finally, the photocatalytic degradation of methylene blue was studied under visible irradiation in aqueous solution, and pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. These results indicated that the presence of GO has an important synergistic effect in conjunction with the natural sensitizer, reaching a photocatalytic yield of 33%.

Decoration of graphene films with europium oxide through the R.F. sputtering technique

MRS Advances ◽  
2019 ◽  
Vol 4 (53) ◽  
pp. 2897-2905
Author(s):  
R. Rangel ◽  
V. J. Cedeño ◽  
J. L. Cervantes ◽  
P. Bartolo-Pérez ◽  
J. A. Montes ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Spatial Distribution ◽  
Photoelectron Spectroscopy ◽  
Graphene Film ◽  
Europium Oxide ◽  
X Ray ◽  
Radio Frequency Sputtering ◽  
Graphene Films ◽  
Europium Concentration ◽  
Main Factor

ABSTRACTThe present work is aimed to study a comparison among synthesized graphene films, deposited on copper substrates and commercial graphene films; both decorated with Eu2O3 particles, with the purpose of promoting photoluminescence. The decoration procedure was achieved using the radio frequency sputtering (R.F. Sputtering) technique for the deposition of Eu2O3 on synthesized or commercial graphene films. The SEM obtained images, show differences in morphology when commercial and synthesized graphene films are compared. Our results indicate that the type of surface is the main factor that accounts for the europium oxide spatial distribution that ultimately leads to luminescence enhancing. The x-ray photoelectron spectroscopy (XPS) analyses, showed the trivalent oxidation state of europium and the atomic content of Europium for both; the commercial graphene film and synthesized one, where the first one presented the higher europium concentration. Analysis by Raman spectroscopy reveals that graphene films become disordered after the decoration is achieved. The main Raman bands of the commercial graphene films undergo a remarkable red shift, as a consequence of the presence of europium oxide It was observed that the interaction of Eu2O3 with the sp2 levels of graphene, improves the red photoluminescence of the samples grown on both, commercial and prepared graphene films.

Metal Deposition on Laser Modified Teflon Surfaces

1995 ◽  
Vol 385 ◽  
Author(s):  
Stefan Lätsch ◽  
Hiroyuki Hiraoka ◽  
Joachim Bargon
Keyword(s):  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Deposition Process ◽  
Metal Deposition ◽  
Polymer Surfaces ◽  
Good Adhesion ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Polymer Adhesion ◽  
Secondary Ion

ABSTRACTCu, Ni, and Au were deposited with defined patterns and good adhesion by electroless plating, e-beam evaporation, and sputtering onto Teflon (polytetrafluoroethylene, PTFE), Teflon ET (PTFE-co-ethylene), Teflon FEP (PTFE-co-hexafluoropropylene) and Teflon PFA (PTFE-coperfluoroalkoxy vinyl ether) surfaces. The polymers had been irradiated in a tetramethyl – ammonium hydoxide solution (TMAH) by a Nd:YAG laser at 266 rim and by an excimer laser at 248 nrm prior to the metal deposition process. Both, the treated and virgin polymer surfaces were characterized by x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and Micro-Raman spectroscopy. The increased metal to polymer adhesion at the interface was found to be due to chemical changes and is in the order Ni > Cu ≅ Au.

Characterization of the influence of fission product doping on the anodic reactivity of uranium dioxide

2007 ◽  
Vol 85 (10) ◽  
pp. 702-713 ◽  
Author(s):  
Heming He ◽  
Peter G Keech ◽  
Michael E Broczkowski ◽  
James J Noël ◽  
David W Shoesmith
Keyword(s):  
Raman Spectroscopy ◽  
Fission Product ◽  
Uranium Dioxide ◽  
Photoelectron Spectroscopy ◽  
Fission Products ◽  
Nuclear Fission ◽  
Lattice Contraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
Dopant Level

The influence of fission product doping on the structure, composition, and electrochemical reactivity of uranium dioxide has been studied using X-ray diffractometry (XRD), scanning electron microscopy (SEM/EDX), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Experiments were conducted on SIMFUEL specimens with simulated burn-ups (increasing doping levels) of 1.5, 3.0, and 6.0 atom%. As the dopant level increased, the lattice contracted, suggesting the dominant formation of dopant-oxygen vacancy clusters. The smaller than expected lattice contraction can be attributed to the segregation of Zr (one of eleven added dopants) to ABO3 perovskite-type phases that SEM/EDX shows also contain Ba, Ce, and possibly some U. Raman spectroscopy shows that doping leads to a loss of cubic symmetry, possibly associated with tetragonal distortions. Raman mapping confirms this loss of cubic symmetry and suggests the specimen is not uniformly doped. Electrochemical experiments show that these distortions lead to a decrease in the oxidative dissolution rate of the UO2 with increased doping density.Key words: UO2, X-ray diffraction, electrochemistry, Raman spectroscopy, nuclear fission products.

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