Epitaxial Growth of Ultrathin Palladium Films on Re{0001}

Etman, Haitham A.; Zheleva, Zhasmina V.; Held, Georg; Bennett, R. A.

doi:10.1021/jp112136f

Cited by 11 publications

(14 citation statements)

References 31 publications

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“…There is a perfect match between the lowest-energy stacking configuration and the one with the lowest Pendry factor (Rp), which corresponds to the best structural fit to the LEED data in Ref. 11. Therefore our theoretical result confirms the preferred growth suggested by experiment, in which the first layer adopts an hcp pseudomorphic structure ABABa; the second layer introduces a stacking fault to give a fcc-like termination ABABac, with subsequent layers growing in an fcc pattern.…”

Section: 1supporting

confidence: 83%

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Electronic Structure of Pd Multilayers on Re(0001): The Role of Charge Transfer

2015

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Understanding the origin of the properties of metal-supported metal thin films is important for the rational design of bimetallic catalysts and other applications, but it is generally difficult to separate effects related to strain from those arising from interface interactions. Here we use density functional (DFT) theory to examine the structure and electronic behavior of fewlayer palladium films on the rhenium (0001) surface, where there is negligible interfacial strain and therefore other effects can be isolated. Our DFT calculations predict stacking sequences and interlayer separations in excellent agreement with quantitative low-energy electron diffraction experiments. By theoretically simulating the Pd core-level X-ray photoemission spectra (XPS) of the films, we are able to interpret and assign the basic features of both low-resolution and highresolution XPS measurements. The core levels at the interface shift to more negative energies, rigidly following the shifts in the same direction of the valence d-band center. We demonstrate 2 that the valence band shift at the interface is caused by charge transfer from Re to Pd, which occurs mainly to valence states of hybridized s-p character rather than to the Pd d-band. Since the d-band filling is roughly constant, there is a correlation between the d-band center shift and its bandwidth. The resulting effect of this charge transfer on the valence d-band is thus analogous to the application of a lateral compressive strain on the adlayers. Our analysis suggests that charge transfer should be considered when describing the origin of core and valence band shifts in other metal / metal adlayer systems.

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Section: 1supporting

confidence: 83%

“…Calculated interlayer distances in comparison with experiment 11. The italicized/bold entries correspond to the Re-Pd interface.…”

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confidence: 99%

Electronic Structure of Pd Multilayers on Re(0001): The Role of Charge Transfer

2015

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“…The experiments were performed in a twin UHV chamber with a base pressure of 10 À10 Torr described in detail previously. 12,13 The Re sample is cleaned by repeated cycles of oxygen treatment at 1500 K for 10 minutes followed by a quick flash to 2300 K. Finally two flashes are required to remove any residual oxygen from the surface. The cleanliness of the surface is confirmed using X-ray photoelectron spectroscopy (XPS), and a sharp low energy electron diffraction (LEED) pattern is observed for clean surfaces, while adsorbed oxygen leads to a pattern indicative of faceting.…”

Section: Methodsmentioning

confidence: 99%

Structure and stress of Re(112̄1); chiral terraces at a racemic surface

Etman

Held

Jenkins

et al. 2013

Phys. Chem. Chem. Phys.

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The surface structure and morphology of the clean Re(1121) surface has been investigated through combined low energy electron diffraction intensity analysis of data taken at multiple angles of incidence, scanning tunneling microscopy, and first-principles density functional calculations. The results show how this globally racemic surface terminates in two chirally distinct terraces, which show large-scale out-of-plane atomic relaxations and in-plane lateral movement of the uppermost atoms. We further identify and discuss the initial stages of step bunching upon adsorption of oxygen that leads ultimately to the large-scale faceting of the surface. Finally, we present calculations of surface stress and the response to applied surface strain, which suggest routes to the exertion of control over the expression of chirality at the surface.

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“…22) and Re(0001). 23 Stated tunneling biases are applied to the sample with the tip at virtual ground. The second apparatus is installed as the end station on beamline I06 of the Diamond synchrotron.…”

Section: Experimental Methodsmentioning

confidence: 99%

Chromium nanostructures formed by dewetting of heteroepitaxial films on W(100)

et al. 2012

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In this paper, we report the surprising formation of square-based facetted islands with linear dimension of the order of 500 nm upon dewetting of a Cr multilayer on W(100). We show that these square islands are composed of inclined facets surrounding a depressed center such that the facet slopes inward with the outer edges of the islands thicker than the centers. The islands' shapes do not represent traditional equilibrium crystal shapes as expected for a Wulf construction. In situ UV and x-ray photoelectron emission microscopy allied to spatially resolved spectroscopy throws considerable light on the nature of the dewetting and shows that the metal surface between the islands remains covered by a thin pseudomorphic wetting layer of ∼1 ML. Low-energy electron diffraction and scanning tunneling and atomic force microscopies allow quantification of facet slopes, and we identify a predominance of tilted Cr(100) facets ± 5 • off of the substrate normal bound by (210) planes at ∼26 • . The epitaxial Cr islands adopt the bulk Cr lattice constant but are tilted with respect to the surface normal. We suggest that the Cr crystallite tilting creates a vicinal-like interface structure that determines the island morphology.

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Epitaxial Growth of Ultrathin Palladium Films on Re{0001}

Cited by 11 publications

References 31 publications

Electronic Structure of Pd Multilayers on Re(0001): The Role of Charge Transfer

Electronic Structure of Pd Multilayers on Re(0001): The Role of Charge Transfer

Structure and stress of Re(112̄1); chiral terraces at a racemic surface

Chromium nanostructures formed by dewetting of heteroepitaxial films on W(100)

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