DETERMINATION OF THE OVERLAYER/SUBSTRATE REGISTRY IN Ni(1 ML)/Pt(111) BY ANGLE-SCANNED PHOTOELECTRON DIFFRACTION

Abstract

The site (fcc or hcp) occupied by the atoms of a Ni ML deposited on Pt (111) is determined in this paper using angle-scanned photoelectron diffraction (PD). A full 2π MgK α-excited Ni-2p 3/2 PD pattern from 1-ML Ni deposited on Pt(111) is compared to single scattering cluster-spherical wave (SSC-SW) simulations and the agreement between experimental and theoretical data is quantified by R-factor analysis. From the present investigation it turns out that Ni atoms occupy hcp sites. In addition, the Ni-Pt distance has been estimated to be 2.5±0.1 Å.

STRUCTURE OF A SINGLE ATOMIC LAYER OF NICKEL DEPOSITED ON THE Pt(111) SURFACE DETERMINED BY LOW ENERGY ELECTRON DIFFRACTION

“…This value also compares well with the Co-Pt bond length determined for 1 ML of Co/Pt(111) (2.63Å). 6 The first Pt interlayer distance is not significantly different from the value of Pt(111) (2.265Å).…”

“…5,6 In the present work, in order to determine the point corresponding to the completion of the first monolayer of Ni deposited on Pt(111), we used a combination of XPS and LEIS. 13 The point at which the Pt signal disappears in the LEIS spectrum was assumed to correspond to the deposition of the first monolayer of Ni.…”

“…5 For 1 ML of Ni deposited on Pt(111), the XPD results seemed to indicate that Ni atoms occupy the other type of threefold hollow sites, namely the hexagonal closedpacked (hcp) sites. 6 However, it should be noted that laboratory-based XPD, employing relatively high kinetic energy electrons, is not very sensitive to the registry of a 2D overlayer with respect to the substrate, 8 whereas the LEED intensities are more sensitive to the registry because of the larger backscattering and multiple scattering contributions.…”