Energetic cluster deposition on a dislocation network: Ag7 on 2 ML Ag/Pt(111)

Jödicke, Harald; Schaub, Renald; Monot, R.; Buttet, J.; Harbich, W.

doi:10.1016/s0039-6028(00)01094-3

Cited by 19 publications

(10 citation statements)

References 20 publications

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“…The evaporated Ag film was subsequently annealed ͑for 5 minutes͒ at 530°C, as reported in literature. [6][7][8][9][10][11] Once the quality and cleanliness of the Ag͑2ML͒/Pt͑111͒ pattern was checked by STM, C 60 molecules were deposited onto the sample kept at RT. The C 60 molecular beam was generated from a Knudsen effusion cell, using a stainless steel crucible containing C 60 powder heated at ϳ400°C, toped by a small opening which limits the sublimating molecules to a narrow solid angle.…”

Section: Methodsmentioning

confidence: 99%

“…In this system, covering clean Pt͑111͒ terraces with 2 monolayers ͑ML͒ of Ag ͓Ag͑2ML͒/Pt͑111͔͒ results in the formation of periodic arrays of crossing dislocations, the so-called dislocation network. [6][7][8][9][10][11] The dislocations ͑or more precisely partial dislocations͒, which are actually discommensuration lines, separate domains of hexagonal close-packed ͑hcp͒ termination from domains of face-centered cubic ͑fcc͒ termination; this can be compared with the Au͑111͒ herringbone reconstruction. 5 This paper reports on the adsorption, growth and structural properties of C 60 thin films deposited at room temperature ͑RT͒ on Ag͑2ML͒/Pt͑111͒ surfaces showing clean and well developed dislocation networks by means of scanning tunneling microscopy ͑STM͒.…”

Section: Introductionmentioning

confidence: 99%

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C60on strain-relief patterns ofAg∕Pt(111): Film orientation governed by templat

et al. 2006

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The adsorption, growth and overlayer formation of C 60 fullerene molecules on strain-relief patterns induced by 2 monolayers of Ag on Pt͑111͒ ͑Ag͑2ML͒/Pt͑111͒͒ is investigated by means of scanning tunneling microscopy. The Ag͑2ML͒/Pt͑111͒ template surface consists of periodic crossing dislocations separating face-centered cubic ͑fcc͒ and hexagonal close-packed ͑hcp͒ stacking domains. At room temperature, C 60 molecules are found to be sufficiently mobile on the template surface to cross the dislocations and to self-assemble into large hexagonally close-packed two-dimensional islands. The nucleation and growth of the C 60 islands takes place not only at the step-edges, but also in the middle of terraces. The islands cover as well fcc as hcp domains of the template, in a near commensurate fashion with respect to the Ag͑2ML͒/Pt͑111͒ superstructure. This commensurability manifests itself by a transfer of the strain relief superstructure into the molecular film via a "lock to register" mechanism. The Ag͑2ML͒/Pt͑111͒ superstructure acts on the molecular film by orientating the C 60 close-packed rows along the Ag͗110͘ direction. This is different from the usual orientation of a C 60 film on a standard and unreconstructed Ag͑111͒ substrate, namely it is rotated by 30°. The C 60 "lock to register" phenomenon can find interpretation in a strong substrate-molecule interaction, which can result in a significant compression of the C 60 lattice. Here, a special role is played by Ag͑2ML͒/Pt͑111͒ small hcp stacking domains enclosed by strong discommensuration lines, foremost responsible for the "lock to register" mechanism.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

C60on strain-relief patterns ofAg∕Pt(111): Film orientation governed by templat

et al. 2006

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“…An important issue in this context is to find a a e-mail: wolfgang.harbich@epfl.ch way to stabilize these nanostructures [18][19][20][21]. A possible way is to pin the particles via the creation of defects to the surface [22][23][24][25][26][27][28]. However these structures although to some extent stable under vacuum conditions at room temperature alter upon exposure to atmospheric conditions or when immersed in solutions.…”

Section: Introductionmentioning

confidence: 99%

Morphology and stability of Au nanoclusters in HOPG nanopits of well-defined depth

et al. 2011

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Abstract. Gold nanoparticles with a diameter comprised between 4 and 6 nm are stabilized in nanosized pits of well defined depth in highly oriented pyrolytic graphite (HOPG). These pits are produced by creation of artificial defects, followed by etching under a controlled oxygen atmosphere. At low Au coverage, clusters are found on the edges of the hexagonal pits maximizing the contact to dangling bonds on graphite multisteps. Larger coverage results in Au beads of surprisingly well defined shape and with a constant bead density per unit length. Most remarkable is the stability of these nanostructures under ambient conditions. Temperatures as high as 650 K do not alter the morphology of the gold clusters. Higher temperatures do not lead to a change of the cluster morphology but to catalytically driven etching of the HOPG substrate.

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“…Therefore also in the 1 ML TN the topmost Ag layer is free of partials, which hence must be buried in the Pt substrate, reminding one of the case of 1 ML Au/Ni(111). 22 An additional feature of the 2 ML Ag TN is that it exhibits an intriguing STM contrast located in the quasihexagons 23 and absent on the SP. Figure 2 shows this contrast with atomic resolution, revealing that 22 ± 2% of the surface atoms appear lower by 0.15Å.…”

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confidence: 99%

Interface-confined mixing and buried partial dislocations for Ag bilayer on Pt(111)

et al. 2012

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The trigonal strain-relief pattern formed by an Ag bilayer on Pt(111) is a prominent example for dislocation networks and their use as nanotemplates. However, its atomic structure has not been solved. Combining scanning tunneling microscopy, low-energy ion scattering, and x-ray photoelectron diffraction, we demonstrate that, unexpectedly, about 22% of the atoms exchange across the Ag/Pt interface, and that the partial dislocations defining the trigonal network are buried in the Pt interface layer. We present an embedded-atom-method simulation identifying the lowest energy structure compatible with all experimental findings. Strain-relief patterns formed by heteroepitaxial films act as templates for the self-assembly of highly ordered nanostructure superlattices. 1 The first system where the growth kinetics has been studied is a superlattice of Ag islands grown on a trigonal network (TN) formed by two monolayers (ML) of Ag/Pt(111). 2,3 The system has been modeled by assuming a network of surface Shockley partial dislocations 4 acting as repulsive line defects and thus confining the deposited Ag adatoms into the (25 × 25) unit cells. 2,3 However, the topmost Ag layer of the TN has recently been shown to be nearly perfectly hexagonal; hence there are no partial dislocations at the surface. 5,6 Nevertheless, the TN exhibits remarkable template functions. Well-ordered sputter holes 5 and adsorbed organic molecules, 6-8 as well as strong spatial variations of the local work function 9 have been reported. A fundamental understanding of any template function evidently requires knowledge of its atomic structure. 10 Despite considerable efforts, a realistic atomistic model has not yet been developed for the 2 ML Ag/Pt(111) TN.Silver on Pt(111) is a system with a particularly rich surface phase diagram. Submonolayers deposited at room temperature (RT) are pseudomorphic for islands smaller than 20 nm, whereas larger islands form surface partial dislocations. 11,12 Counterintuitively, the dislocations disappear at a full monolayer (defined as one Ag atom per Pt substrate atom), where the stress resulting from the misfit is largest. This has been related to the chemical adatom potential and to the presence of an adatom gas. 11 Further growth at RT leads to a striped phase (SP) 4,13 with pairs of partial dislocations. Upon annealing to 800 K the SP transforms into the stable TN structure. 4 Deposition of Ag submonolayers at higher temperature, or their annealing at T > 620 K, leads to a real mixture formed by monolayer Ag clusters embedded into the uppermost atomic substrate layer for a coverage < 0.5 ML and the reverse for 0.5 ML < < 1.0 ML. 14 This mixing has been confirmed by CO titration 15 and He-atom scattering 16 and is confined to the uppermost layer; hence, the name "surface alloy". 17 For 1.0 ML, especially for = 2 ML, Ag and Pt were believed to be phase separated up to the Ag desorption temperature.In this paper we report the surprising observation that the system mixes again for 2 ML Ag in the TN structure. This mi...

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Energetic cluster deposition on a dislocation network: Ag7 on 2 ML Ag/Pt(111)

Cited by 19 publications

References 20 publications

C60on strain-relief patterns ofAg∕Pt(111): Film orientation governed by templat

C60on strain-relief patterns ofAg∕Pt(111): Film orientation governed by templat

Morphology and stability of Au nanoclusters in HOPG nanopits of well-defined depth

Interface-confined mixing and buried partial dislocations for Ag bilayer on Pt(111)

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