Island shapes and intermixing for submonolayer nickel on Au(111)

Cullen, William; First, Phillip N.

doi:10.1016/s0039-6028(98)00817-6

Cited by 58 publications

(62 citation statements)

References 29 publications

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“…al [14] and in some cases it is already active at room temperature, as previously reported for Pt and Ni [4,8]. Our STM measurements confirm that such a process is actually occurring at room temperature also in the case of palladium.…”

supporting

confidence: 90%

“…This preferential growth presents common features such as the position of nucleation sites and island faceting along the close-packed 0 1 1 directions, but also some relevant differences. First of all, various degrees of intermixing between the surface and the adlayer have been reported, ranging from the case of nickel [8] and platinum [4], for which the growth of islands with mixed composition has been observed at room temperature, to the one of iron [5] and palladium [1], showing nucleation of gold-free islands. Moreover, a variety of different situations are found concerning the interplay between islands and surface during the growth process: such interactions can lead to the onset of island preferential growth along specific directions [9] and to significant distortion or even lifting of the herringbone reconstruction [1], [10].…”

Section: Introductionmentioning

confidence: 99%

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Direct observation of the basic mechanisms of Pd island nucleation on Au(111)

et al. 2009

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The formation mechanisms of evaporated Pd islands on the reconstructed Au(111) 22 × 3 herringbone surface have been here studied by Scanning Tunneling Microscopy (STM) at room temperature. Atomically resolved STM images at the very early stages of growth provide a direct observation of the mechanisms involved in preferential Pd islands nucleation at the elbows of the herringbone structure. At low Pd coverage the Au(111) herringbone structure remains substantially unperturbed and isolated Pd atoms settled in hollow sites between Au atoms are found nearby the elbows and the distortions of the reconstructed surface. In the same regions, at extremely low coverage (0.003 ML), substituted Pd atoms in lattice sites of the Au(111) surface are also observed, revealing the occurrence of a place exchange mechanism. Substitution seems to play a fundamental role in the nucleation process, forming aggregation centres for incoming atoms and thus leading to the ordered growth of Pd islands on Au(111). Atomically resolved STM images of Pd islands reveal a close-packed arrangement with lattice parameter close to the interatomic distance between gold atoms in the fcc regions of the Au(111) surface. Distortion of the herringbone structure for Pd coverages higher than 0.25 ML indicates strong interaction between the growing islands and the topmost Au(111) layer.

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supporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Direct observation of the basic mechanisms of Pd island nucleation on Au(111)

et al. 2009

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“…The remaining surface shows a reconstruction similar to that in Fig. 3(c), which is taken as an indication of the formation of random intermixing between the two metals [12,32]. Upon further annealing screw dislocations decrease in number and the contrast of the top layer becomes more homogeneous [ Fig.…”

Section: High Coverage Regime (From Above Ca 1 ML To Ca 20 Ml)mentioning

confidence: 80%

“…For the coppergold system different top layer structures have been proposed: segregation [7,30,35,36], complete encapsulation, whereby a single layer of copper is covered by a single layer of gold [32,[36][37][38] and intermixing [28,32,[36][37][38][39][40] have been considered. Often varying electronic contrast observed via STM when imaging an island has been considered as an indication that the top layer is of mixed (random) composition, as in surface solid solution [12,32,[41][42][43]. In the present case, as already highlighted, considering the growth behavior and the almost uniform contrast across an island [44], albeit increased in correspondence of the corrugation, the preference goes for an almost pure copper double layer, the first of which is incorporated within the top gold layer [1].…”

Section: Resultsmentioning

confidence: 99%

“…Nucleation of guest metals on Au(111) generally occurs via the place-exchange mechanism [5], which was initially ruled out for the adsorption of copper; however, it was later reported that the onset of copper adsorption does occur via a place-exchange mechanism, at specific sites identified as the narrowed regions within the highly reactive elbows of the Au(111)-(22× √ 3), irrespective of hcp or fcc stacking [1]. Other than for copper [6][7][8], this is also the case for other transition metals such as nickel [9][10][11][12], iron [13,14], and chromium [15,16], to name a few. Added clusters are regarded as a source of reactive metal atoms, over a surface commonly considered as a 2D inert support, opening up the possibility of modifying the reactivity of the Au(111) surface itself, via the formation of surface alloys, whereby both the added metal and gold are present in the top layer.…”

Section: Introductionmentioning

confidence: 99%

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Structure and Reactivity of Cu-doped Au(111) Surfaces

Grillo

Megginson

Christie

et al. 2018

e-J. Surf. Sci. Nanotech.

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The structure and surface chemistry of ultrathin metallic films of one metal on another are strongly influenced by factors such as lattice mismatch and the formation of near-surface alloys. New morphologies may result with modified chemical properties which in turn open up different routes for molecular adsorption, desorption and surface functionalization, with important consequences in several fields of application.The Cu/Au(111) system has received the attention of many studies, only a few however have been performed in ultra-high vacuum (UHV), using surface sensitive techniques. In this contribution, the room temperature deposition of copper onto the (22× √ 3)-Au(111) surface, from submonolayer to thick film, is investigated using scanning tunnelling microscopy (STM).The onset of copper adsorption is seen to occur preferentially at alternate herringbone elbows, with a preference for hcp sites. With increasing coverage, copper-rich islands exhibit a reconstructed surface reminiscent of the clean Au(111) herringbone reconstruction. Disordered, pseudo-ordered and ordered surface layers are observed upon annealing. Models for the initial adsorption/incorporation mechanism, formation of adlayers and evolution with increasing coverage and annealing are qualitatively discussed. Further, the reactivity of copper-doped Au (111) systems is considered towards the adsorption of organic molecules of interest in nanotechnology and in catalytic applications.

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