I M McLeod

Publications (4)5.09 Total impact

• Article: The evolution of the electronic structure at the Bi/Ag(111) interface studied using photoemission spectroscopy.

  K H L Zhang, I M McLeod, M Lahti, K Pussi, V R Dhanak
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  ABSTRACT: The growth of Bi on Ag(111) induces different surface structures, including [Formula: see text] surface alloy, Bi-[Formula: see text] overlayer and Bi(110) thin film, as a function of increasing Bi coverage. Here we report the study of electronic states of these structures using core level and valence band photoemission spectroscopy at room temperature. The sp-derived Shockley surface state on Ag(111) is rapidly quenched upon deposition of Bi, due to the strong variation of the in-plane surface potential in the Ag(2)Bi surface alloy. The Bi 4f core levels of the [Formula: see text] alloy and Bi(110) thin film are shifted to lower binding energy by ∼0.6 eV and ∼0.3 eV compared with the Bi bulk value, respectively. Mechanisms inducing the core level shifts are discussed as due to a complex superposition of several factors. As Bi coverage increases and a Bi(110) overlayer forms on Ag(111), a new state is observed at ∼0.9 ML arising from electronic states localized at the Ag-Bi interface. Finally the change of work function as a function of coverage is discussed on the basis of a charge transfer model.
  Journal of Physics Condensed Matter 10/2012; 24(43):435502. · 2.55 Impact Factor
• Article: LEED I-V and DFT structure determination of the (√3 × √3)R30° Pb-Ag(111) surface alloy.

  I M McLeod, V R Dhanak, M Lahti, A Matilainen, K Pussi, K H L Zhang
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  ABSTRACT: The deposition of 1/3 of a monolayer of Pb on Ag(111) leads to the formation of PbAg(2) surface alloy with a long range ordered (√3 × √3)R30° superstructure. A detailed analysis of this structure using low-energy electron diffraction (LEED) I-V measurements together with density functional theory (DFT) calculations is presented. We find strong correlation between experimental and calculated LEED I-V data, with the fit between the two data sets having a Pendry's reliability factor of 0.21. The Pb atom is found to replace one top layer Ag atom in each unit cell, forming a substitutional PbAg(2) surface alloy, as expected, with the Pb atoms residing approximately 0.4 Å above the Ag atoms due to their size difference. DFT calculations are in good agreement with the LEED results.
  Journal of Physics Condensed Matter 07/2011; 23(26):265006. · 2.55 Impact Factor
• Article: Structure determination of the Bi–Ag(111) surface alloy using LEED I–V and DFT analyses

  I.M. McLeod, V.R. Dhanak, A. Matilainen, M. Lahti, K. Pussi, K.H.L. Zhang
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  ABSTRACT: The deposition of 1/3 of a monolayer of Bi on Ag(111) leads to the formation of BiAg2 surface alloy with a long range ordered superstructure. A detailed analysis of this structure using LEED I–V measurements together with DFT calculations is presented. We find strong correlation between experimental and calculated LEED I–V data, with the fit between the two data sets having a Pendry's reliability factor of 0.16. The Bi atom is found to replace one top layer Ag atom in each unit cell, forming a substitutional BiAg2 surface alloy, with the Bi atoms residing approximately 0.6 Å above the Ag atoms due to their size difference. DFT calculations are in good agreement with the LEED results.
  Surface Science. 604:1395-1399.
• Article: Observation of a surface alloying-to-dealloying transition during growth of Bi on Ag(111)

  K. H. L. Zhang, I. M. McLeod, Y. H. Lu, V. R. Dhanak, A. Matilainen, M. Lahti, K. Pussi, R. G. Egdell, X.-S. Wang, A. T. S. Wee, W. Chen
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  ABSTRACT: The atomic structures that develop as a function of coverage during deposition of Bi on Ag(111) have been studied using low-temperature scanning tunneling microscopy, low-energy electron diffraction, and ab initio calculations. The growth process involves two sequential stages. At low coverage, Bi atoms are incorporated into the topmost layer of Ag(111), resulting in the formation of an Ag2Bi alloy confined to the surface and ordered (√3×√3)R30° Ag2Bi islands supported on Ag(111). This mode of accommodation of Bi was found to be energetically favorable based on ab initio total-energy calculations. At coverage above a critical value of 0.55 monolayers, the Ag2Bi alloy phase gradually converts into an ordered Bi (p×√3) overlayer structure supported on Ag(111). We postulate that the dealloying transition is likely driven by compressive strain induced by incorporation of large-size Bi atoms into Ag at a high coverage and the subsequent lack of miscibility of Ag and Bi bulk phases. After completion of the dealloying process, Bi(110) thin films can be grown epitaxially on top of Ag(111) with a chemically abrupt interface.
  Phys. Rev. B. 83(23).