The Experts below are selected from a list of 99855 Experts worldwide ranked by ideXlab platform
Jun Kawai - One of the best experts on this subject based on the ideXlab platform.
-
total reflection x ray photoelectron spectroscopy as a semiconductor lubricant elemental Analysis method
2015Co-Authors: Abbas Alshehabi, Nobuharu Sasaki, Jun KawaiAbstract:Abstract Photoelectron spectra from a typical hard disk storage media device (HDD) were measured at total reflection and non-total reflection at unburnished, acetone-cleaned, and argon-sputtered conditions. F, O, N, and C usually making the upper layer of a typical hard disk medium were detected. Enhancement of the photoelectron emission of the fluorocarbon lubricant was observed at total reflection. Pt and Co were only found by non-total X-ray photoelectron spectroscopy (XPS) because they are constituents of a deeper region than the top and interface regions. Argon-sputtered, ultrasonic acetone-cleaned, and unburnished top layers were compared at total and non-total reflection conditions. Total reflection X-ray photoelectron spectroscopy (TRXPS) is demonstrated to be a powerful tool for storage media lubrication layer Chemical State Analysis, reliable for industrial quality control application , and reproducible.
-
Quantitative Chemical State Analysis of Supported Vanadium Oxide Catalysts by High Resolution Vanadium Kα Spectroscopy
2011Co-Authors: Takashi Yamamoto, Fumitaka Nanbu, Tsunehiro Tanaka, Jun KawaiAbstract:Oxidation States of vanadium species on Al2O3, SiO2, and TiO2 were quantitatively analyzed by least-squares fitting of V Kα spectra recorded with a two-crystal X-ray fluorescence spectrometer. Uncertainties of analytical results by the normalization procedure, and coefficient of validation and the reduction behavior of vanadium species by X-ray irradiation were discussed. The V5+/V4+/V3+ ratios on Al2O3, SiO2, and TiO2 calcined at 773 K in air were determined to be ca. 6/3/1, 3/6/1, and 5/4/1, respectively. The possible Chemical States of vanadium species on supports were proposed.
-
Sulfur Chemical State Analysis of diesel emissions of vehicles using X-ray absorption
2006Co-Authors: Satoshi Matsumoto, Yoshinori Kitajima, Yoichi Tanaka, Hideshi Ishii, Teruo Tanabe, Jun KawaiAbstract:Abstract Soft X-ray absorption spectra of sulfur K edge were measured for diesel exhaust particles from three different vehicles. The X-ray spectra were measured using a synchrotron radiation beamline. The spectra were measured by surface sensitive total electron yield method and bulk sensitive X-ray fluorescence yield method. One vehicle concentrated the S 2− on the surface of the emission particles; the others did not concentrate S 2− . This type of Chemical State Analysis method is useful for the process Analysis such as diesel emissions.
-
Depth selective Chemical State Analysis of Pb and S in fly ash in municipal solid waste incinerators using X-ray absorption spectroscopy
2003Co-Authors: Jun Kawai, Yoshinori Kitajima, Susumu Tohno, Orlando E. Raola, Masaki TakaokaAbstract:Abstract Soft X-ray absorption spectra of sulfur K edge and lead M4,5 edges were measured for fly ash samples collected from two types of municipal solid waste incinerators. The X-ray spectra were measured using a synchrotron radiation beam line. The spectra were measured by surface sensitive total electron yield method and bulk sensitive X-ray fluorescence yield method. The instruments to measure the X-ray absorption spectra were an electric current amplifier and a proportional counter. The spectra recorded with these two yield methods were different for one incinerator sample and same for the other incinerator sample. This observation was supported from the X-ray fluorescence quantitative elemental Analysis of Pb. One type of incinerator concentrated the lead on the surface of the fly ash particles. The other did not concentrate lead. This type of depth selective Chemical State Analysis method is useful for the process Analysis such as an incinerator.
-
High resolution soft X-ray absorption spectroscopy for the Chemical State Analysis of Mn
2000Co-Authors: Jun Kawai, Yoshinobu Mizutani, Tetsuro Sugimura, Makoto Sai, Tohru Higuchi, Yoshihisa Harada, Yoichi Ishiwata, Akiko Fukushima, Masami Fujisawa, M. WatanabeAbstract:Abstract Mn L 2,3 X-ray absorption spectra of various manganese compounds were measured using a synchrotron radiation facility. Very high-resolution spectra were obtained. Sharp lines, which were not found before, were observed, and reproducibility was checked using a different beam line in the synchrotron radiation facility. Difference in spectral line shape was observed as the difference of quantum yield method. An unknown sample was measured and the specimen was concluded to be a mixture of two different oxidation States of Mn. The effects on the change of spectral profiles are discussed.
Matjaž Kavčič - One of the best experts on this subject based on the ideXlab platform.
-
Chemical State Analysis of Phosphorus Performed by X-ray Emission Spectroscopy.
2015Co-Authors: Marko Petric, R. Bohinc, Klemen Bučar, Matjaž Žitnik, Jakub Szlachetko, Matjaž KavčičAbstract:An experimental and theoretical study of phosphorus electronic structure based on high energy resolution X-ray emission spectroscopy was performed. The Kα and Kβ emission spectra of several phosphorus compounds were recorded using monochromatic synchrotron radiation and megaelectronvolt (MeV) proton beam for target excitation. Measured spectra are compared to the results of ab initio quantum Chemical calculations based on density functional theory (DFT). Clear correlation between energy position of the Kα emission line and the phosphorus formal oxidation State as well as DFT-calculated number of valence electrons is obtained; measured energy shifts are reproduced by the calculations. Chemical sensitivity is increased further by looking at the Kβ emission spectra probing directly the structure of occupied molecular orbitals. Energies and relative intensities of main components are given together with the calculated average atomic character of the corresponding molecular orbitals involved in transitions.
-
Chemical State Analysis employing sub natural linewidth resolution pixe measurements of kα diagram lines
2005Co-Authors: Matjaž Kavčič, Andreas G. Karydas, Ch. ZarkadasAbstract:A high-energy resolution crystal spectrometer in Johansson geometry, which allows energy resolution below the natural linewidth of the Ka diagram lines, was employed in the measurements of proton-induced Ka x-ray emission spectra of titanium and sulfur pure and compound targets. The results demonstrate a clear dependence of the Ka energy shifts on the Chemical State of the element in the sample. This dependence permits the Chemical State speciation of low-Z elements in an unknown sample by employing high-resolution PIXE measurements of the Ka line. The potential of the technique in speciation studies is demonstrated in the case of an aerosol sample. The Analysis of the Ka line obtained from the high-energy resolution proton-induced S Ka x-ray spectrum allowed the identification of sulfur in the aerosol sample as sulfate ([SO 4 ] 2- ).
-
Chemical State Analysis of sulfur in samples of environmental interest using high resolution measurement of Kα diagram line
2004Co-Authors: Matjaž Kavčič, Andreas G. Karydas, Ch. ZarkadasAbstract:Abstract The proton induced Kα X-ray emission spectra of pure and some compound targets of sulfur were measured with a crystal spectrometer in Johansson geometry, which enables energy resolution below the natural linewidth of the measured Kα line. From these measurements the absolute energies of the S-Kα 1,2 lines were experimentally determined. In addition, the energies of the KαL 1 X-ray satellite lines, appearing in these spectra as a result of the radiative decay of atomic States with one hole in the K shell and one in the L subshells, were also measured. The measured Kα diagram and satellite line energies depend crucially on the S Chemical State. The measured diagram line energies, as well as their relative intensity ratios obtained from the X-ray spectra of different S compounds, allow the deconvolution of X-ray spectra of mixed targets containing two different S compounds and the accurate determination of their mass ratio. Finally, the proton induced S-Kα X-ray spectrum from an aerosol sample was collected and the measured energies of the Kα 1,2 lines were used to specify the Chemical State of S in the aerosol as a sulfate ([SO 4 ] 2− ). In conclusion, the results of the present paper demonstrate that the S-Kα 1,2 emission energies depend on the S Chemical State and, therefore, their determination allows the Chemical State speciation of S in a given sample.
Sh M Abdelwahab - One of the best experts on this subject based on the ideXlab platform.
-
enhanced the photocatalytic activity of ni doped zno thin films morphological optical and xps Analysis
2016Co-Authors: Asim Jilani, I.s. Yahia, Sh M Abdelwahab, A A AlghamdiAbstract:Abstract Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV–Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and Chemical State Analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.
I.s. Yahia - One of the best experts on this subject based on the ideXlab platform.
-
Chemical State Analysis, optical band gap, and photocatalytic decolorization of cobalt-doped ZnO nanospherical thin films by DC/RF sputtering technique
2018Co-Authors: Asim Jilani, M. Sh. Abdel-wahab, H.y. Zahran, I.s. Yahia, Attieh A. Al-ghamdi, Ahmed Alshahrie, A.m. El-naggarAbstract:Abstract We have used direct current radio frequency (DC/RF) sputtering to deposit cobalt- incorporated zinc oxide (Co:ZnO) thin films on glass substrate. The x-ray diffraction (XRD) was applied for structural observation while topography was examined by atomic force microscopy (AFM). The optical studies were carried out by UV–vis absorption spectroscopy. The elemental composition was performed via x-ray photoelectron spectroscopy (XPS). The Chemical State studies were also investigated. The shifting of XRD pattern towards higher diffraction angle confirmed successful incorporation. The optical observation showed “d–d” electron transition during the thin film deposition. The photocatalytic response was carried through the degradation of methylene blue (MB). The improved photocatalytic behavior of Co:ZnO thin films were attributed to the high binding energy component (HBEC) of oxygen vacancies. We have also proposed the tentative mechanism of cobalt incorporation into ZnO through XPS finding. We also checked the stability of deposited thin films. Co:ZnO thin films are new attractive candidates for degradation of waste dyes.
-
enhanced the photocatalytic activity of ni doped zno thin films morphological optical and xps Analysis
2016Co-Authors: Asim Jilani, I.s. Yahia, Sh M Abdelwahab, A A AlghamdiAbstract:Abstract Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV–Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and Chemical State Analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.
A A Alghamdi - One of the best experts on this subject based on the ideXlab platform.
-
enhanced the photocatalytic activity of ni doped zno thin films morphological optical and xps Analysis
2016Co-Authors: Asim Jilani, I.s. Yahia, Sh M Abdelwahab, A A AlghamdiAbstract:Abstract Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV–Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and Chemical State Analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.