@article {1548, title = {Density functional theory calculation of 2p core-electron binding energies of Si, P, S, Cl, and Ar in gas-phase molecules}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {151}, number = {1}, year = {2006}, note = {ISI Document Delivery No.: 017GXTimes Cited: 12Cited Reference Count: 40}, month = {Mar}, pages = {9-13}, type = {Article}, abstract = {Density functional theory (DFT) calculations have been performed on the gas-phase 2p core-electron binding energies (CEBEs) of Si and Ar in 145 cases using the following procedure: AEKS (scalar-ZORA + E-xc)/TZP//HF/6-31G(d). Delta E-KS is the difference in the total Kohn-Sham energies of the 2p-ionized cation and the neutral parent molecule calculated by DFT using different exchange-correlation functionals E-xc with triple-zeta polarized basis set, at molecular geometry optimized by HF/6-31G(d), and relativistic effects have been estimated by scalar zeroth-order regular approximation. Among the 26 functionals tested, the form of E-xc giving the best overall performance was found to be the combination of OPTX exchange and LYP correlation functionals. For that functional, the average absolute deviation (AAD) of the 145 calculated CEBEs from experiment is 0.26 cV. There are seven other exchange-correlation functionals that led to AADs of less than 0.30 eV. Some functionals give lower AADs than E-xc=OPTX-LYP for some individual elements. In the case of Si, for example, the combination of either mPW91-PBE or Becke88-Perdew86 led to an AAD of only 0.10 eV for 56 silicon-containing molecules. Another example is the case of the argon atom, for which the choice of E-xc=OPTX-Perdew86 yields a value for CEBE equal to the experimental value. (c) 2005 Elsevier B.V. All rights reserved.}, keywords = {ABSORPTION, ACCURATE, Ar(2p), ARGON, BEHAVIOR, Cl(2p), emission, ESCA, EXCHANGE-ENERGY, GENERALIZED GRADIENT APPROXIMATION, L-shell ionization, P(2p), POTENTIALS, RAY PHOTOELECTRON-SPECTROSCOPY, S(2p), Si(2p), SILICON, XPS}, isbn = {0368-2048}, url = {://000235683200003}, author = {Segala, M. and Takahata, Y. and Chong, D. P.} } @article {1002, title = {Is HAM/3 (Hydrogenic Atoms in Molecules, Version 3) a semiempirical version of DFT (density functional theory) for ionization processes?}, journal = {Journal of the Brazilian Chemical Society}, volume = {15}, number = {2}, year = {2004}, note = {ISI Document Delivery No.: 823IBTimes Cited: 7Cited Reference Count: 69}, month = {Mar-Apr}, pages = {282-291}, type = {Article}, abstract = {We calculated valence-electron vertical ionization potentials (VIPs) of nine small molecules, plus uracil and C2F4, by several different methods: semiempirical HAM/3 and AM1 methods, different nonempirical DFT models such as uDI(B88-P86)/cc-pVTZ and -epsilon(SAOP)/TZP, and ab initio Hartree-Fock (HF)/cc-pVTZ. HAM/3 reproduced numerical values more closely to those calculated by the nonempirical DFTs than to those obtained by HF method. Core-electron binding energies (CEBEs) of aniline, nitrobenzene and p-nitro aniline, were also calculated by HAM/3 and nonempirical DeltaFT using DE method. A nonempirical DFT model, designated as DeltaE(KS) (PW86-PW91)/TZP model, resulted accurate CEBEs ( average absolute deviation of 0.14 eV) with high efficiency. Although absolute magnitude of HAM/3 CEBEs has error as much as 3 eV, the error in the chemical shifts DeltaCEBE is much smaller at 0.55 eV. While the CEBE results do not lead to any definite answer to the question in the title, the trends in valence-electron VIPs indicate that HAM/3 does not approximate DFT with accurate exchange-correlation potentials, but seems to simulate approximate functionals such as B88-P86.}, keywords = {ACCURATE, BASIS-SET, CEBE, DFT, ELECTRON BINDING-ENERGIES, ESCA, EXCHANGE-ENERGY, HAM-3, HAM/3, MO THEORY, ORGANIC-MOLECULES, RAY PHOTOELECTRON-SPECTROSCOPY, SPECTRA, SUBSTITUTED BENZENES, vertical ionization potential, ZETA}, isbn = {0103-5053}, url = {://000221603000019}, author = {Takahata, Y. and Chong, D. P. and Segala, M.} } @article {560, title = {Insertion and removal of protons in single-crystal orthorhombic molybdenum trioxide under H2S/H-2 and O-2/N-2}, journal = {Chemistry of Materials}, volume = {14}, number = {4}, year = {2002}, note = {ISI Document Delivery No.: 542DRTimes Cited: 13Cited Reference Count: 49}, month = {Apr}, pages = {1788-1796}, type = {Article}, abstract = {Using AFM/XRD/XPS methods, in this paper, we investigate protonation and deprotonation processes in single-crystal samples of orthorhombic molybdenum trioxide (alpha-MoO3). At low temperatures, a small part of alpha-MoO3 is changed to needlelike HxMoO3 (x approximate to 0.33) along <203> directions in a H2S/H-2 gas stream. When these elongated crystallites assemble into a maze structure, the growth of HxMoO3 is gradually ceased due to closing entrance for hydrogen. At higher temperatures, the needlelike HxMoO3 crystallites turn to a growth perpendicular to <203>, which leads to the formation of HxMoO3 blocks. It is observed that the basal plane of alpha-MoO3 is severely buckled upon the protonation. Surface sulfidation is also observed. The formed HxMoO3 or surface MOS2, however, can be readily converted back to their original-phase alpha-MoO3 in air at 350-400 degreesC. This oxidation process gives rise to a flattened (010) topography (i.e., debuckling) on which shallowly divided alpha-MoO3 surface blocks bounded with {101} planes are formed. When an alpha-MoO3 (010) plane embedded with nanocrystallites is used to create surface stress or nucleation sites, the insertion mode of hydrogen along <001> is further reconfirmed in this work. A correlation of surface/bulk phases upon various chemical reactions is addressed, and a model to summarize these changes is also proposed.}, keywords = {BRONZES, DECOMPOSITION, GROWTH, HXMOO3, HYDROGEN, MOO3, NUCLEAR-MAGNETIC-RESONANCE, RAY PHOTOELECTRON-SPECTROSCOPY, SILICA SUPPORTS, THIN-FILMS, XPS}, isbn = {0897-4756}, url = {://000175028700050}, author = {Zeng, H. C. and Xie, F. and Wong, K. C. and Mitchell, K. A. R.} } @article {5206, title = {XPS study of interfaces in a two-layer light-emitting diode made from PPV and Nafion with ionically exchanged Ru(bpy)(3)(2+)}, journal = {Applied Surface Science}, volume = {174}, number = {1}, year = {2001}, note = {ISI Document Delivery No.: 416RQTimes Cited: 13Cited Reference Count: 39}, month = {Apr}, pages = {43-50}, type = {Article}, abstract = {X-ray photoelectron spectroscopy (XPS) was used to investigate the interfacial chemistries occurring in a prototype two-layer polymer light-emitting diode that had been fabricated from PPV and Nafion with ion-exchanged Ru(bpy)(3)(2 +) Magnesium and indium tin oxide (ITO) were used as electrodes, and XPS observations were made as the different layers were added sequentially. Specifically, Mg was deposited on a layer of Nafion with incorporated Ru(bpy)(3)(2 +), and this was itself deposited on PPV-coated ITO. The morphology of Nafion, which is dictated by the strongly hydrophilic and hydrophobic groups that compose it, is indicated to rearrange with the incorporation of Ru(bpy)(3)(2 +) this rearrangement appears reinforced when a thin film is deposited on PPV. The Mg deposition results in substantial changes in XPS spectra, in part due to a direct interaction with the fluorocarbon backbone of Nation. (C) 2001 Elsevier Science B.V. All rights reserved.}, keywords = {CHEMISTRY, conjugated polymers, COPOLYMERS, ELECTROLUMINESCENCE, FILMS, luminescence, MEMBRANES, NAFION, POLYETHYLENETEREPHTHALATE, polymer light-emitting diodes, RAY PHOTOELECTRON-SPECTROSCOPY, ruthenium polypyridyl complex, SYSTEMS, X-ray photoelectron spectroscopy}, isbn = {0169-4332}, url = {://000167794300006}, author = {Susac, D. and Kono, M. and Wong, K. C. and Mitchell, K. A. R.} } @article {4946, title = {Accurate density-functional calculation of core-electron binding energies of some substituted benzenes}, journal = {Bulletin of the Chemical Society of Japan}, volume = {73}, number = {11}, year = {2000}, note = {ISI Document Delivery No.: 380KRTimes Cited: 7Cited Reference Count: 32}, month = {Nov}, pages = {2453-2460}, type = {Article}, abstract = {The core electron binding energies (CEBE{\textquoteright}s) of benzene, seven monosubstituted benzenes (Ph-X) and one disubstituted benzene (p-NH2-C6H4-NO2) were calculated using density-functional theory (DFT). The unrestricted generalized transition-state (uGTS) model was employed. The DeMon DFT program with a combined functional of Becke{\textquoteright}s exchange (B88) with Perdew{\textquoteright}s correlation (P86) was used. The average absolute deviation of the calculated CEBE{\textquoteright}s of the title compounds was 0.3 eV when the cc-pVDZ basis set was used. The "CEBE shift" of the ring carbon in Ph-X was calculated while taking the CEBE on the ring carbon in Ph-H as a reference. The thus-calculated CEBE shifts agree with experiment within the value of the average absolute deviation, 0.1 eV. The signs and quantitative numerical values of the CEBE shifts are very close to the corresponding Hammett sigma constants.}, keywords = {APPROXIMATION, BORON, DERIVATIVES, GAS, PARAMETERS, RAY PHOTOELECTRON-SPECTROSCOPY, SPECTRA, ZETA BASIS-SET}, isbn = {0009-2673}, url = {://000165701500004}, author = {Takahata, Y. and Chong, D. P.} } @article {3916, title = {Recent advances in the practical and accurate calculation of core and valence XPS spectra of polymers: from interpretation to simulation?}, journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms}, volume = {131}, number = {1-4}, year = {1997}, note = {ISI Document Delivery No.: YC279Times Cited: 5Cited Reference Count: 712nd International Symposium on Ionizing Radiation and Polymers (IRaP 96)NOV 03-08, 1996GUADELOUPE, FRANCECEA Saclay, DSM DRECAM, Univ Antilles Guyane, Int Atom Energy Agcy, Inst Oberflachenmodifizierung}, month = {Aug}, pages = {1-12}, type = {Proceedings Paper}, abstract = {Core and valence X-ray Photoelectron Spectroscopies (XPS) are routinely used to obtain information on the chemical composition, bonding and homogeneity of polymer surfaces. In spite of their apparent conceptual simplicity, Core and Valence Electron Binding Energies (CEBEs and VEBEs) a few electron-volts (eV) or fractions of an eV apart are difficult to interpret. We present some results obtained with various recent theoretical. approaches. An emphasis is made on a procedure based on the Density Functional Theory (DFT) that enables the calculation of CEBEs and VEBEs which are in remarkable agreement with experiment. The method has been tested on numerous small (3-6 atoms) to fairly large (15-25 atoms) molecules, and shows an average absolute deviation with experiment of only 0.20 eV for CEBEs and 0.30 eV for VEBEs, i.e. compatible with the resolution of the best XPS experiments carried out at the moment. Besides the quality of its predictions, the procedure takes advantage of the speed and CPU time scaling of DFT as a function of system size: it is computationally tractable, even for surprisingly large systems such as polymers, and may be an interesting accurate alternative to interpret and simulate XPS-probing on real systems, We illustrate the usefullness and pitfalls of this approach in fundamental as well as applied fields such as in the study of Polyacrylonitrile (PAN), Polytetrafluoroethylene (PTFE), Polyvinyldifluoride (PVdF) and gamma-Aminopropyltriethoxysilane (gamma-APS, an adhesion promoter). (C) 1997 Elsevier Science B.V.}, keywords = {DENSITY-FUNCTIONAL CALCULATION, ELECTRON BINDING-ENERGIES, ESCA, GREEN-FUNCTION, IONIZATION-POTENTIALS, MO METHOD, MODEL MOLECULES, POLYACRYLONITRILE, POLYETHYLENE LAMELLAE, RAY PHOTOELECTRON-SPECTROSCOPY}, isbn = {0168-583X}, url = {://A1997YC27900005}, author = {Bureau, C. and Chong, D. P. and Endo, K. and Delhalle, J. and Lecayon, G. and LeMoel, A.} } @article {3313, title = {ANALYSIS OF VALENCE XPS OF (CH2-CHR)(N) (R=H, CH3, OH AND F), (CH2-CH2-NH)(N) AND (CH2-CH2-O)(N) POLYMERS BY THE SEMIEMPIRICAL HAM/3 MO METHOD USING THE N-MER (N=2, 3, 4, 5) MODEL}, journal = {Journal of Physics and Chemistry of Solids}, volume = {56}, number = {8}, year = {1995}, note = {ISI Document Delivery No.: RF331Times Cited: 26Cited Reference Count: 50}, month = {Aug}, pages = {1131-1140}, type = {Article}, abstract = {The valence X-ray photoelectron spectra (XPS) of six representative polymers [CH2-CHR)(n) (R = H, CH3, OH, F), (CH2-CH2-NH)(n), and (CH2-CH2-O)(n)] were analysed by a semi empirical HAM/3 MO method using model molecules [H-(CH2-CHR)(n)-H, (R = H, CH3, OH, F), H2N-(CH2-CH2-NH)(n)-H, and HO-(CH2-CH2-O)(n)-H] with n = 2 to 5. The calculated AlK alpha photo electron spectra were obtained using Gaussian functions of an approximate linewidth (0.10I(k)); I-k = I{\textquoteright}(k) - WD, where I{\textquoteright}(k); is the vertical ionization potential (VIP) of each MO and WD is a shift to account for sample work function, polarization energy and other effects. To explain the broader linewidth for the inner valence spectra, we propose that the lifetime of the 2s hole states are shorter because the holes can be filled by 2p electrons in ultra-violet emission or radiationless transition. The theoretical spectra showed good agreement with the observed spectra of the polymers between 0-40 eV. The present results suggest that the spectra can be analysed by the calculations for model trimers.}, keywords = {BAND, CLUSTER-EXPANSION, Electronic Structure, ELECTRONIC-STRUCTURE, ENERGY-LEVELS, ESCA, IONIZATION, photoelectron spectroscopy, POLYETHYLENE, POLYMERS, POLYOXYMETHYLENE, RAY PHOTOELECTRON-SPECTROSCOPY, SPECTRA, WAVEFUNCTION}, isbn = {0022-3697}, url = {://A1995RF33100017}, author = {Endo, K. and Kaneda, Y. and Aida, M. and Chong, D. P.} } @article {3563, title = {XPS INVESTIGATIONS OF THE INTERACTIONS OF HYDROGEN WITH THIN-FILMS OF ZIRCONIUM-OXIDE .1. HYDROGEN TREATMENTS ON A 10-ANGSTROM THICK-FILM}, journal = {Applied Surface Science}, volume = {89}, number = {3}, year = {1995}, note = {ISI Document Delivery No.: RG147Times Cited: 19Cited Reference Count: 19}, month = {Jul}, pages = {255-261}, type = {Article}, abstract = {Interactions of hydrogen with the interface formed between ZrO2 and zirconium suboxide (ZrOx, x < 2) were studied on a 10 Angstrom zirconium oxide film prepared on gold foil for X-ray photoelectron spectroscopy (XPS) analysis. This film was subject to a set of sequential treatments. Reaction with II, gas at 2 mbar pressure and room temperature indicates that the ZrO2/ZrOx interface appeared to undergo a redox-type reaction and convert to a new ZrO2/ZrOy (x < y < 2) film. Heating this structure at 300 degrees C in a 10(-9) mbar vacuum (residual gas dominantly H2O) resulted in more ZrO2 in the outer region and less ZrO, in the subsurface. By contrast, when this film was treated with a hydrogen plasma, XPS showed enhanced formation of -OH groups and complete conversion to the ZrO2-like form. On heating to 300 degrees C, this uniform film regenerates the ZrO2/ZrOy interface structure, apparently with desorption of H2O.}, keywords = {OXYGEN, RAY PHOTOELECTRON-SPECTROSCOPY, SIMS, SURFACE OXIDATION, ZRO2}, isbn = {0169-4332}, url = {://A1995RG14700005}, author = {Wong, P. C. and Li, Y. S. and Zhou, M. Y. and Mitchell, K. A. R.} } @article {3056, title = {XPS AND CORROSION STUDIES ON ZINC PHOSPHATE COATED 7075-T6 ALUMINUM-ALLOY}, journal = {Journal of Materials Science}, volume = {29}, number = {5}, year = {1994}, note = {ISI Document Delivery No.: NA770Times Cited: 11Cited Reference Count: 19}, month = {Mar}, pages = {1368-1373}, type = {Article}, abstract = {X-ray photoelectron spectroscopy (XPS), combined with scanning electron microscopy (SEM), weight loss tests and atomic absorption spectroscopy (AAS), has been applied to investigate the corrosion protection properties of zinc phosphate when coated on 7075-T6 aluminium alloy. XPS is consistent with the coating process leading to both physically adsorbed and chemically absorbed zinc. The former is washed away by ultrasonic washing, but the chemically absorbed component, identified as ZnO(x), is incorporated into the aluminium oxide layer. This layer helps suppress the dissolution of aluminium during the corrosion process.}, keywords = {PRIMER, RAY PHOTOELECTRON-SPECTROSCOPY, SURFACES}, isbn = {0022-2461}, url = {://A1994NA77000034}, author = {Heung, W. F. and Yang, Y. P. and Wong, P. C. and Mitchell, K. A. R. and Foster, T.} } @article {2928, title = {XPS STUDIES OF THE STABILITY AND REACTIVITY OF THIN-FILMS OF OXIDIZED ZIRCONIUM}, journal = {Applied Surface Science}, volume = {72}, number = {3}, year = {1993}, note = {ISI Document Delivery No.: MF104Times Cited: 21Cited Reference Count: 32}, month = {Nov}, pages = {237-244}, type = {Article}, abstract = {X-ray photoelectron spectroscopy (XPS) has been used to characterize thin films formed by the deposition of zirconium on to gold foil. With deposition rates of the order of 1 angstrom min-1, in the presence of an atmosphere of 10(-9) mbar H2O, the film has an outer region Of ZrO2 and inner regions of a lower oxidation state material, ZrO(x), and Zr-Au alloy. Initially both ZrO(x) and Zr-Au alloy are oxidized by either H2O or O2 at 300-degrees-C, although this process is hindered as the ZrO2 layer gets thicker. However, even with the protective oxide layer, heating in 5 x 10(-7) mbar D2 (with a partial pressure of 10(-9) mbar H2O) can convert ZrO(x) to ZrO2, a reaction apparently facilitated by migrating D atoms.}, keywords = {ADSORPTION, AES, BINDING-ENERGY SHIFTS, electron, HYDROGEN, OXIDATION, OXYGEN, RAY PHOTOELECTRON-SPECTROSCOPY, SINGLE-CRYSTAL, SURFACES, ZR}, isbn = {0169-4332}, url = {://A1993MF10400004}, author = {Wang, Y. M. and Li, Y. S. and Wong, P. C. and Mitchell, K. A. R.} } @article {7305, title = {XPS STUDIES OF INTERFACES BETWEEN GAMMA-GLYCIDOXYPROPYLTRIMETHOXYSILANE AND ALUMINUM SURFACES}, journal = {Applied Surface Science}, volume = {59}, number = {1}, year = {1992}, note = {ISI Document Delivery No.: HW731Times Cited: 37Cited Reference Count: 15}, month = {May}, pages = {23-29}, type = {Article}, abstract = {Angular-dependent X-ray photoelectron spectroscopy (ADXPS) has been used to characterize interfaces formed by gamma-glycidoxypropyltrimethoxysilane (gamma-GPS) deposited on to aluminum panel surfaces. The application of a negative biasing potential to the sample with a thin gamma-GPS layer on chemically etched aluminum reveals an extra peak in the Al 2p spectra which is tentatively assigned to the effect of direct Si-O-Al bonding between silane and aluminum oxide. The dual approach of combining the ADXPS and bias potential techniques should have more general application to the non-destructive study of polymer/metal interfaces.}, keywords = {POLYMER SYSTEMS, RAY PHOTOELECTRON-SPECTROSCOPY}, isbn = {0169-4332}, url = {://A1992HW73100003}, author = {Leung, Y. L. and Zhou, M. Y. and Wong, P. C. and Mitchell, K. A. R. and Foster, T.} } @article {7132, title = {OXIDE THICKNESS EFFECT AND SURFACE ROUGHENING IN THE DESORPTION OF THE OXIDE FROM GAAS}, journal = {Applied Physics Letters}, volume = {59}, number = {4}, year = {1991}, note = {ISI Document Delivery No.: FX626Times Cited: 49Cited Reference Count: 10}, month = {Jul}, pages = {464-466}, type = {Article}, abstract = {The temperature for thermal desorption of the gallium oxide from GaAs is shown to increase linearly with oxide thickness. In addition, we show by diffuse light scattering that highly polished GaAs substrates roughen during the oxide desorption. These results are interpreted in terms of a model in which the oxide evaporates inhomogeneously.}, keywords = {MOLECULAR-BEAM EPITAXY, RAY PHOTOELECTRON-SPECTROSCOPY}, isbn = {0003-6951}, url = {://A1991FX62600029}, author = {Vanbuuren, T. and Weilmeier, M. K. and Athwal, I. and Colbow, K. M. and Mackenzie, J. A. and Tiedje, T. and Wong, P. C. and Mitchell, K. A. R.} }