S. R. Haines

University of Liverpool, Liverpool, ENG, United Kingdom

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Publications (12)20.48 Total impact

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    ABSTRACT: Disorder broadening of core-level binding energies is a general effect observed in random alloys, and identifies an opportunity for studying specific local environments experimentally. Here we study it in an archetypical system: face-centered-cubic Cu50Au50. While the disorder broadening is clearly detectable at Au, at Cu it is below the detection limit. We supplement experiments by a theoretical study where we model the alloy by a large supercell constructed as a special quasirandom structure and calculate binding-energy shifts at all sites in the supercell. Theory shows that the suppression of the disorder broadening at Cu results from a delicate balance between the influence of local chemical environment and inhomogeneous lattice distortions on the site-resolved core-level shifts. Surprisingly, even larger relaxation-induced shifts are observed at Au sites.
    Physical review. B, Condensed matter 01/2009; 79(1). · 3.77 Impact Factor
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    ABSTRACT: The electron spectroscopy of poly(dimethylsiloxane) (PDMS) and PDMS following oxygen plasma treatment and subsequent exposure of the plasma-treated surface to glycine are compared. The results obtained for the Auger parameter show no significant differences, whereas the results for the valence band spectra are consistent with the changes that are expected to occur as a result of the replacement of CH3 groups by oxygen and OH groups during the plasma treatment and by the adsorption of glycine. Differences observed in line shape of the Si KLV spectra for PDMS and pure Si are attributed to the changes in the local Si environment in PDMS. The oxygen plasma treatment introduces a small shift in the local p DOS to lower binding energies and exposure of the plasma-treated surface to glycine introduces a similar small shift in the p DOS to higher binding energies. Copyright © 2007 John Wiley & Sons, Ltd.
    Surface and Interface Analysis 12/2007; 39(12‐13):942 - 947. · 1.39 Impact Factor
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    ABSTRACT: High-energy X-ray photoelectron spectroscopy (XPS) is of particular importance for minimizing the effects of surface contamination by increasing photoelectron escape depths. In this study high-resolution high-energy Cu Kα1 and soft Al Kα1 XPS and Auger electron spectroscopy were used to compare the electronic structure of Ti in TiO2 powder and Ti metal. The Ti 1s in TiO2 XPS line is narrower and more symmetric than in Ti metal. A comparison of the relative intensities of the L23M23M45 and L23M23M23 Auger transitions in Ti metal and TiO2 is consistent with the expected transfer of Ti 3d electrons away from the Ti site in the oxide. The satellites accompanying the Ti 1s XPS line excited by Cu Kα1 X-rays occur at the same energies as the satellites accompanying the Ti 2s and 2p XPS lines excited by Al Kα1 X-rays indicating that they do not depend on the core-level, the experimental resolution or inelastic scattering processes.
    Journal of Electron Spectroscopy and Related Phenomena 07/2006; 152(3):148-151. · 1.71 Impact Factor
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    ABSTRACT: High-energy X-ray photoelectron spectroscopy is a valuable technique for the study of the electronic and chemical states of materials. Here we present the specification, capabilities and restrictions of a recently built Cu Kα1 X-ray source (hν = 8047.8 eV) and discuss a range of potential applications. Preliminary results from a study of Ti metal and TiO2 powder are presented with emphasis on the Ti 1s intrinsic plasmon loss and the Auger-parameter shift. Comparison with data obtained from conventional soft X-ray photoelectron spectroscopy (hν = 1486.6 eV) demonstrates the advantage of the Cu Kα1 source. Copyright © 2006 John Wiley & Sons, Ltd.
    Surface and Interface Analysis 03/2006; 38(4):703 - 706. · 1.39 Impact Factor
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    ABSTRACT: The 1s XPS spectra of the 3d transition metals from Sc to Co have been measured using a monochromated Cu Kα1 (hν=8047.8eV) excitation source. Quantitative analysis has been carried out by line-shape curve fitting. The results show that the separation between the main peak and the maximum of the intrinsic energy loss feature increases with the number of 3d electrons. In addition the intensity of the intrinsic energy loss increases with the number of unpaired electrons in the valence band. However, the width of the zero energy loss peak shows the opposite behaviour and decreases with the number of unpaired electrons.
    Journal of Electron Spectroscopy and Related Phenomena - J ELECTRON SPECTROSC RELAT PH. 01/2006; 152(3):129-133.
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    ABSTRACT: A precursor site which is likely to be involved in the formation of graphite on the diamond (100) 1×2 surfaces has been created by bombardment with low energy Ar ions and characterised by high resolution X-ray photoelectron spectroscopy (XPS) of the C 1s photoelectron line.
    Journal of Electron Spectroscopy and Related Phenomena - J ELECTRON SPECTROSC RELAT PH. 01/2006; 152(1):33-36.
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    ABSTRACT: We compare the results of ab initio calculations with measured reflection anisotropy spectra and show that strongly bound surface-state excitons occur on the clean diamond (100) surface. These excitons are found to have a binding energy close to 1 eV, the strongest ever observed at a semiconductor surface. Important electron-hole interaction effects on the line shape of the optical transitions above the surface-state gap are also found.
    Physical Review Letters 04/2005; 94(8):087404. · 7.73 Impact Factor
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    ABSTRACT: A Cu Kα1 sealed tube X-ray source (hν=8047.8eV) and LiF(220) Johansson geometry monochromator crystal have been interfaced to a Scienta ESCA300 spectrometer for high energy XPS studies of materials, in particular for the measurement of Auger parameters associated with deep core levels in metallic alloys. The detailed arrangement of the source, monochromator and spectrometer combination is described, and factors affecting the overall intensity and resolution are discussed. The optimisation and characterisation of the system are also described. Several examples of Cu Kα1 excited survey spectra (Cr, Fe, stainless steel), deep core level spectra (Cr 1s, Fe 1s) and Auger spectra (Cr KLL, Cr LMM, Fe KLL) are presented, which illustrate the capability of the system. Auger vacancy satellites are identified in the Cr LMM spectrum. For a series of Cr–Si alloys measurements are reported of the change in the Cr Auger parameter on going from metal to alloy.
    Journal of Electron Spectroscopy and Related Phenomena 01/2005; 142(2):151-162. · 1.71 Impact Factor
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    ABSTRACT: The design of monochromated x-ray sources for high-energy XPS is of particular importance. Prediction of the final result and the effect of the experimental parameters is very important if optimum performance is to be obtained in practice. A computer program has been written to calculate crystal reflectivity, collection solid angle and integrated beam intensity for any singly and doubly bent crystal diffractor. The intensity profile, size and shape of the image-spot produced by the diffracted x-rays on any arbitrary plane are then predicted by ray tracing. The application of the program to optimize a LiF(220) crystal with Johansson geometry for Cu K (8047.78 eV) will be demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
    Surface and Interface Analysis 01/2004; 36(8):1119-1121. · 1.39 Impact Factor
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    ABSTRACT: The construction of an x-ray source for high-energy XPS studies, based on Cu Ka1 radiation (hv = 8047.8 eV), is described. This source has been fitted to a Scienta ESCA300 electron spectrometer and initial results for pure iron, chromium and stainless steel are presented. The Fe 1 s and Cr 1 s core levels (at 7112 and 5989 eV binding energy, respectively) are readily observed at good resolution along with their KLL Auger series. It is concluded that the new source shows much promise for investigation of the electronic structure of ferrous and other alloys of scientific and technological importance.
    Surface and Interface Analysis 01/2004; 36(3):275-279. · 1.39 Impact Factor
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    ABSTRACT: High resolution core level photoelectron spectra for a series of AgxPd1−x alloys have been measured and reveal a large “disorder broadening” effect. A comparison of measurements of this effect for three alloy systems, AgxPd1−x, CuxPd1−x and CuxZn1−x, with results of ab initio calculations is presented. Poor agreement is obtained and possible reasons for this observation are discussed.
    Journal of Electron Spectroscopy and Related Phenomena - J ELECTRON SPECTROSC RELAT PH. 01/2004; 136(3):235-238.
  • S. R Haines, A. W Newton, P Weightman
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    ABSTRACT: High resolution measurement of the core level photoelectron spectra of disordered alloys of CuPd have revealed a broadening contribution arising from compositional disorder [Phys. Rev. Lett. 78 (1997) 3777]. The effect has also been observed in disordered alloys of CuPt [J. Electron. Spectrosc. 107 (2000) 185] and CuZn [J. Phys. Condens. Matter 11 (1999) 8431]. In determining the magnitude of the disorder broadening contribution to a core level lineshape, it is necessary to allow for the contribution from the surface shifted components. In this work the contribution from surface shifted components of the core level spectra is evaluated for the CuxPd(x−1) (x=0.88, 0.5, 0.12) system from high resolution measurements of the spectra obtained at take off angles of 90° and 10°. The results show that the presence of surface components does not compromise the determination of the bulk contribution to disorder broadening of core level lines.
    Journal of Electron Spectroscopy and Related Phenomena - J ELECTRON SPECTROSC RELAT PH. 01/2004; 137:429-434.