Charge-induced formation of linear Au clusters on thin MgO films: Scanning tunneling microscopy and density-functional theory study

Abstract

Gold deposition onto ultrathin MgO films on Ag͑001͒ results in the formation of linear Au clusters, as revealed from a combined scanning tunneling microscopy and density-functional theory study. The equilibrium structure of small Au clusters containing three to seven atoms is therefore different on thin film and bulk MgO͑001͒ but also deviates from the shape of the respective gas-phase clusters. The peculiar one-dimensional growth regime of gold is stimulated by an electron transfer from the MgO/Ag interface to the deposited Au clusters, resulting in singly and doubly charged cluster anions. Only for larger atom numbers, the formation of compact two-dimensional clusters prevails on the MgO thin films.

New directions in point-contact spectroscopy based on scanning tunneling microscopy techniques (Review Article)

“…It has been observed that one-dimensional chains assemble spontaneously along the [001] direction of a thin alumina film deposited on a NiAl(110) surface; single-atom chains have been identified by imaging the surface after atom deposition [64,74]. A very similar phenomenon has been observed on top of an ultrathin MgO film deposited onto a Ag(001) surface [75]. Lifting single-atom chains requires an extremely accurate control of the manipulation process and also a significantly high stability of the system.…”

“…Similar experiments to the one described in Ref. have been performed a few years later using a thin (5 Å) insulating film deposited on a metallic surface as substrate to deposit single gold atoms [64,74,75]. It has been observed that one-dimensional chains assemble spontaneously along the [001] direction of a thin alumina film deposited on a NiAl(110) surface; single-atom chains have been identified by imaging the surface after atom deposition [64,74].…”

“…The NiAl(110) surface works thus as a natural template for the assembly of gold chains. Similar experiments have been performed a few years later using an insulating film deposited on a metallic surface as substrate to deposit single gold atoms [64,74,75]. In order to assemble chains consisting in single nanoscale devices atoms in the chain have to be strongly bound to each other, their electronic properties have to reflect the one-dimensional nature of the built structure.…”

Characterizing low-coordinated atoms at the periphery of MgO-supported Au islands using scanning tunneling microscopy and electronic structure calculations

“…They also exhibit a high tendency to accumulate excess charges that have been transferred from the support. 8,9 Finally, the cluster perimeter is easily accessible for mobile reactants that either diffuse on the metal aggregate or migrate on the oxide surface. This proximity of metal and oxide binding sites renders the periphery atoms ideal candidates to sustain chemical reactions.…”

Tailoring oxide properties: An impact on adsorption characteristics of molecules and metals

“…The large modifications in adsorption owing to the metal support are not limited to Au or other transition metal single atoms, but significant changes are also seen in Au cluster geometries, charge states, and adsorption energies on metal-supported MgO films [107][108][109][110][111] . For comparison, on bulk MgO the smallest Au N (N=2-6) clusters favour minimal wetting with 14 one or two Au atoms in contact with oxide ions 28,94,108,112,113 .…”