XPS Spectra (xp + spectrum)

Distribution by Scientific Domains


Selected Abstracts


A study of the mechanisms of divalent copper binding to a modified cellulose adsorbent

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
David William O'Connell
Abstract A modified cellulose material was prepared by grafting glycidyl methacrylate to cellulose (Cell- g -GMA) with subsequent functionalization with imidazole (Cell- g -GMA-imidazole). This latter compound was used in the adsorption of copper from aqueous solution. The mechanism of Cu(II) binding onto the cell- g -GMA-imidazole was investigated at the molecular level using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), x-ray photoelectron spectroscopy (XPS), energy dispersive x-ray analysis (EDX) and X-ray diffraction (XRD). FTIR and Raman spectroscopy provided an insight into the extent to which perturbation of the imidazole ring occurred following adsorption of the metal while XPS spectra indicated the binding of Cu(II) ions to nitrogen atoms by the appearance of additional binding energy peaks for nitrogen on the cellulose- g -GMA-imidazole sample post adsorption. The EDX technique provided clear evidence of the physical presence of both the copper and sulfate on the cellulose- g -GMA-imidazole material post adsorption. XRD analysis further confirmed the presence of a copper species in the adsorbent material as copper sulfate hydroxide (Cu3(OH)4SO4 - antlerite). The XRD studies further suggest that the overall extent of Cu(II) adsorption is not alone a combination of true metal chelation as suggested by FTIR, Raman and XPS, but also a function of surface precipitation of the polynuclear copper species. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]


Photografting of unable-to-be-irradiated surfaces.

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007

Abstract In this article, a batch liquid-phase process was reported, by which the photo-initiated grafting polymerization could be carried out on the dark surfaces that were not directly irradiated by UV light. In the reaction system, an aluminum foil was placed horizontally to reflect UV light back and form a dark area underneath where the grafting polymerization took place. The occurrence of the polymerization was demonstrated by gravitational analyses and XPS spectra. The factors affecting the grafting reaction have been studied and the results showed that increasing irradiation time, reaction temperature, and benzophenone concentration and decreasing distance (D) between the light area and the place where grafting reaction took place were beneficial to the grafting reaction. The highest grafting density was obtained at a acrylic acid concentration of 15 vol %. Moreover, some further investigations were also made. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 118,124, 2007 [source]


Influence of boron concentration on the XPS spectra of the (100) surface of homoepitaxial boron-doped diamond films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2006
S. Ghodbane
Abstract As-grown (100) homoepitaxial diamond films with boron concentrations [B] from 4.6 × 1016 to 1.5 × 1021 cm,3 have been analysed using X-ray photoelectron spectroscopy (XPS). Their C 1s core levels contain a dominant component around 284.17 ± 0.2 eV ascribed to sp3 C and a main secondary component around 284.88 ± 0.2 eV ascribed to CHx (x , 2) on surface defects. Their relative concentration decreases and increases, respectively, as [B] increases. A significant component around 286.4 ± 0.2 eV ascribed to ether group (C,O,C) remains nearly constant up to [B] , 3 × 1020 cm,3, then increases for greater boron concentrations. Other components around 283.0 ± 0.2, 287.69 ± 0.2 and 288.76 ± 0.2 eV ascribed, respectively, to sp2 C, carbonyl (C=O) and carboxyl (HO,C=O) on surface defects remain with low concentrations. The occurrence of these XPS components, their assignments and their relative concentrations are satisfactorily compared to those previously found for IIb crystals with (100) surface and for polycrystalline films with [B] around 1019 and 7 × 1020 cm,3. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Electronic and transport properties of Dy2Co7B3 compound

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003
A. Kowalczyk
Abstract New results of the electronic and transport properties (electrical resistivity) of Dy2Co7B3 compound are reported. This alloy crystallizes in the hexagonal Ce2Co7B3 type of structure. The electronic structure has been studied by the X-ray photoemission spectroscopy (XPS). The valence band of the XPS spectra is determined mainly by the Co(3d) and Dy(4f) bands. The peaks positions are in good agreement with binding energies of a metallic dysprosium and cobalt. The resistivity at low temperatures shows a T2 dependence. At higher temperatures the resistivity is no linear function of temperature, which indicates an electron-phonon interaction in the presence of a small s-d scattering. [source]


Electronic structure of RCoxGe2 (R=Ce, Pr, Gd) compounds

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2006
B. Penc
Abstract The electronic structure of the RCoxGe2 (R=Ce, Pr, Gd) compounds with the orthorhombic crystal structure of CeNiSi2 -type was studied by X-ray photoemission spectroscopy. The valence bands of CeCo0.86Ge2 and PrCo0.85Ge2 compounds have the similar character. Near the Fermi level the broad peak corresponding to the Co 3d and R 4f and 5d6s states is observed. In the case of GdCo0.64Ge2, the strong intensity peak at 8.7 eV corresponding to Gd 4f states is observed. The analysis of the XPS spectra of Ce and Pr 3d5/2 and 3d3/2 in the Gunnarson-Schönhammer model give the information on the hybridization of the f orbital with the conduction band. The hybridization energy equal 93 eV for R=Ce and 143 eV for R=Pr, respectively indicate stability of the shell in these compounds. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Enhanced surface sensitivity in secondary ion mass spectrometric analysis of organic thin films using size-selected Ar gas-cluster ion projectiles

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 10 2010
Motohiro Tanaka
A size-selected argon (Ar) gas-cluster ion beam (GCIB) was applied to the secondary ion mass spectrometry (SIMS) of a 1,4-didodecylbenzene (DDB) thin film. The samples were also analyzed by SIMS using an atomic Ar+ ion projectile and X-ray photoelectron spectroscopy (XPS). Compared with those in the atomic-Ar+ SIMS spectrum, the fragment species, including siloxane contaminants present on the sample surface, were enhanced several hundred times in the Ar gas-cluster SIMS spectrum. XPS spectra during beam irradiation indicate that the Ar GCIB sputters contaminants on the surface more effectively than the atomic Ar+ ion beam. These results indicate that a large gas-cluster projectile can sputter a much shallower volume of organic material than small projectiles, resulting in an extremely surface-sensitive analysis of organic thin films. Copyright © 2010 John Wiley & Sons, Ltd. [source]


Highly Efficient Visible Light Plasmonic Photocatalyst Ag@Ag(Br,I)

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2010
Peng Wang
Abstract The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag+ ions in the surface region of Ag(Br,I) particles to Ag0 species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83,nm to 1,,m. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce CrVI under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I). [source]


Formation of Oxynitride as the Photocatalytic Enhancing Site in Nitrogen-Doped Titania Nanocatalysts: Comparison to a Commercial Nanopowder,

ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005
X. Chen
Abstract A nitrogen-doped TiO2 nanocolloid has been successfully prepared and its properties compared with the commercially available TiO2 nanomaterial, Degussa P25. Several characterization techniques, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Raman scattering, and UV-visible reflectance spectra, are combined in order to determine the crystal phase and grain size, shape, degree of nitrogen incorporation, and nature of the resultant oxynitride chemical bonding on the surface and in the bulk. The high relative photocatalytic activity of the nitrogen doped-TiO2 nanocolloid is evaluated through a study of the decomposition of methylene blue under visible light excitation. The ease and degree of substitutional-insertional nitrogen doping is held accountable for the significant increase in photocatalytic activity in the porous nanocolloid versus the nitrided commercial nanopowder. It is suggested that the nitrogen incorporation produces an NO bonding region as evidenced by the resulting XPS spectrum. [source]