Morphological Studies of Small Three-Dimensional Gold Clusters on Graphite by Scanning Tunnelling Microscopy

Humbert, A.; Pierrisnard, R.; Sangay, S.; Chapon, C.; Henry, Claude R.; Claeys, Corneel

doi:10.1209/0295-5075/10/6/005

Cited by 20 publications

(9 citation statements)

References 11 publications

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“…in figure 5(d), which is due to the large average cluster size of more than 5 nm. As has been shown before for supports with a threefold symmetry axis, the clusters grow in the (111) epitaxy and have a threedimensional tetrahedral shape [8,36], which they keep up to sizes of a few nanometres [2]. Clusters with larger sizes than 5 nm exhibit different equilibrium shapes, namely truncated tetrahedrons [2], as shown by TEM and STM [36][37][38].…”

Section: S133mentioning

confidence: 84%

Imaging nanoclusters in theconstant height modeof the dynamic SFM

et al. 2006

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For the first time, high quality images of metal nanoclusters which were recorded in the constant height mode of a dynamic scanning force microscope (dynamic SFM) are shown. Surfaces of highly ordered pyrolytic graphite (HOPG) were used as a test substrate since metal nanoclusters with well defined and symmetric shapes can be created by epitaxial growth. We performed imaging of gold clusters with sizes between 5 and 15 nm in both scanning modes, constant f mode and constant height mode, and compared the image contrast. We notice that clusters in constant height images appear much sharper, and exhibit more reasonable lateral shapes and sizes in comparison to images recorded in the constant f mode. With the help of numerical simulations we show that only a microscopically small part of the tip apex (nanotip) is probably the main contributor for the image contrast formation. In principle, the constant height mode can be used for imaging surfaces of any material, e.g. ionic crystals, as shown for the system Au/NaCl(001).

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Section: S133mentioning

confidence: 84%

Imaging nanoclusters in theconstant height modeof the dynamic SFM

et al. 2006

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“…15 The most recent results suggest that primarily the low-coordinated atoms are bonding sites for CO and O 2 , 9,[16][17][18][19] and that the interaction with the substrate 14,20 or charge transfer could also play a role in the catalysis by gold clusters. 12,13 Scanning probe microscopy offers an excellent possibility for in situ studies of the properties of nanoclusters, and scanning tunneling microscopy ͑STM͒ has been applied to several model systems, [21][22][23][24][25][26] but the requirement of a conducting sample has restricted the STM's access to the important class of insulating surfaces. In principle dynamic scanning force microscopy ͑dynamic SFM͒ [27][28][29] offers the capability of imaging both the adsorbed metal clusters and the insulating surface in atomic resolution, hence providing unprecedented information about the cluster structural properties.…”

Section: Introductionmentioning

confidence: 99%

High-resolution scanning force microscopy of gold nanoclusters on the KBr (001) surface

et al. 2006

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In this study we use a combination of dynamic scanning force microscopy experiments and first-principles simulations to study the imaging process of gold nanoclusters adsorbed on the ͑001͒ surface of KBr. In previous experiments atomic resolution was readily obtained on the KBr substrate. However, it was not possible to resolve atoms within the clusters themselves. This correlates with imaging simulations we present here using several different probable tip models: measurable contrast was readily achieved on the KBr surface and on the gold ͑001͒ surface, but simulations on the clusters demonstrated poor contrast for all tips. We further consider the role of cluster charging in the tip-surface interaction, and the role that surface defects play in the properties of adsorbed clusters.

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“…So studies of clusters on surfaces have great physical and technical importance. Some experiments [8,9] have shown that the surface may play an important role in determining the structure and the stability of clusters. In a recent experiment [10] involving Au and Ag clusters supported on a tungsten tip, the melting point of the clusters was found to be a constant value when the diameter of the clusters was less than 2 nm; some authors [11] have suggested that this may be attributed to the strong interaction between the clusters and the surfaces.…”

Section: Introductionmentioning

confidence: 99%

The structure and stability of clusters on surfaces

Sun

Gong

1997

J. Phys.: Condens. Matter

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The structure and the stability of clusters on surfaces are simulated by using the constant-energy molecular-dynamics method. The necessary condition for a cluster to be supportable on a surface is studied. It is found that the lattice mismatch has a strong effect on the stability of clusters on surfaces; the structures obtained are surface dependent. The thermal stability of the supported clusters on surfaces is also investigated.

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Morphological Studies of Small Three-Dimensional Gold Clusters on Graphite by Scanning Tunnelling Microscopy

Cited by 20 publications

References 11 publications

Imaging nanoclusters in theconstant height modeof the dynamic SFM

Imaging nanoclusters in theconstant height modeof the dynamic SFM

High-resolution scanning force microscopy of gold nanoclusters on the KBr (001) surface

The structure and stability of clusters on surfaces

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