STM Investigations on Compact Au
                    <sub>55</sub>
                    Cluster Pellets

Houbertz, R.; Feigenspan, Th.; Mielke, F.; Memmert, U.; Hartmann, Uwe; Simon, Ulrich; Schön, Günter; Schmid, G.

doi:10.1209/0295-5075/28/9/005

Cited by 52 publications

(18 citation statements)

References 5 publications

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“…This is certainly the case for STS experiments with cluster pellets. [65] The formation of 2D cluster arrangements by the LB and SA methods described in Section 2.2 presents another chance to study Au 55 clusters by STS. In contrast to the complex 3D assemblies in pellets or cluster aggregations from solution, 2D films promise a reduction of the unknown parameters.…”

Section: Propertiesmentioning

confidence: 99%

Metal Clusters and Colloids

Schmid¹,

Lifeng

1998

Adv. Mater.

313

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Section: Propertiesmentioning

confidence: 99%

Metal Clusters and Colloids

Schmid¹,

Lifeng

1998

Adv. Mater.

313

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“…Among them, extended x-ray absorption fine-structure spectroscopy [2], x-ray absorption near edge spectroscopy [2], specific heat measurements [3], optical spectroscopy [4,5], scanning tunneling spectroscopy [6], atomic force microscopy [7], ac-and dcconductivity measurements [8], impedance spectroscopy [9], Mössbauer spectroscopy [10], as well as x-ray-induced photoelectron spectroscopy (XPS) [11,12] have been used to obtain access to the structural and electronic properties of Au 55 particles protected by a triphenylphosphine ligand shell. In addition, first principles calculations have been performed [13,14] for the naked clusters (i.e., Au 55 without any ligands) aiming to serve as a reference system for the cluster compound.…”

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confidence: 99%

Chemically Induced Metal-to-Insulator Transition inAu55Clusters: Effect of Stabilizing Ligands on the Electronic Properties of Nanoparticles

et al. 2001

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The cluster compound Au55(PPh3)12Cl6 has been reanalyzed by photoelectron spectroscopy giving direct evidence for a nonmetallic behavior of the individual Au clusters as long as their ligand shell remains intact. The exposure to x-rays during the measurements is found to partly decompose the shell by removal of the chlorine atoms, resulting in a metallic behavior of the clusters as demonstrated by a steplike intensity at the Fermi energy. These observations resolve a long-standing controversy about the metallic behavior of ligated Au clusters emphasizing, in addition, the influence of the local environment on the electronic properties of nanoscaled materials.

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“…Scanning tunneling microscopy and local tunneling spectroscopy has been applied to measure the electronic properties of compact Au 55 cluster pellets [8] or solvent-evaporated Au 55 and Pt 309 clusters on various substrates [9,10]. Singleelectron tunneling on these systems has been clearly observed in the current-voltage (I-V ) curves.…”

mentioning

confidence: 99%

Single-electron tunneling in Au 55 cluster monolayers

Chi

Hartig

Drechsler

et al. 1998

Applied Physics A: Materials Science & Processing

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Metallic nanometer clusters composed of 55 gold atoms isolated from each other by a thin organic ligand film, with a total diameter of 2.1 nm, were fabricated as monolayers on various technically relevant substrates by using a two-step self-assembly (SA) procedure as well as combined Langmuir-Blodgett (LB) and SA techniques. Scanning tunneling microscopy (STM) and scanning force microscopy (SFM) studies on these systems reveal a short-range close packing of these clusters. Single-electron tunneling (SET) phenomena, including Coulomb blockade and Coulomb staircase, are studied by local tunneling spectroscopy (LTS) at room temperature as well as at low temperature (90-100 K). A narrow spread of the charge energy is observed on such prepared cluster monolayers.In recent years, nanometer-sized clusters of metals separated from each other by organic ligand shells have received increasing scientific interest [1]. These clusters have a welldefined size in the metal core, with a fixed number of metal atoms, and are stabilized by the organic ligand shell. Thus, they provide excellent model systems for monodispersed metal clusters, embedded in a dielectric matrix for the investigation of physical properties related to nanoscale particles. Among the various clusters, Au 55 (PPh 3 ) 12 Cl 6 (in short Au 55 ) and Pt 309 Phen 36 O 30 (in short Pt 309 ), have been intensely studied by different groups [2-6]. The possible electronic application of these metal clusters, with diameters of 1.4-2.1 nm, as "quantum dots" was first discussed by Schön and Simon [7].Scanning tunneling microscopy and local tunneling spectroscopy has been applied to measure the electronic properties of compact Au 55 cluster pellets [8] or solvent-evaporated Au 55 and Pt 309 clusters on various substrates [9, 10]. Singleelectron tunneling on these systems has been clearly observed in the current-voltage (I-V ) curves. In previous investigations, the cluster solutions were dropped on a substrate and then dried, or the clusters were compressed to a pellet. The * Corresponding author quantitative analysis of I-V curves is based to some extend on the undefined geometric packing of the clusters. The charge energy had a wider spread than expected [10]. Further, in LTS investigations, one interesting question is addressed: whether the additional structures on the Coulomb staircase measured at 4.2 K might be induced by the interaction between the substrate and the clusters or by that between the ligand molecules and the metal core [10]. A uniform packing of clusters on the substrate will help to rule out some unknown effects for the quantitative analysis, since modification of the charging energy of a cluster might be affected by its environment. In addition, achieving ordered arrays of these metal dots is an essential step for developing nanoscale electronic devices [11].Recently, the closed packing of gold clusters, each encapsulated by a monolayer of alkyl thiol molecules, has been successfully achieved by spin casting [12]. As is known, spin casting of suspens...

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STM Investigations on Compact Au ₅₅ Cluster Pellets

Cited by 52 publications

References 5 publications

Metal Clusters and Colloids

Metal Clusters and Colloids

Chemically Induced Metal-to-Insulator Transition inAu55Clusters: Effect of Stabilizing Ligands on the Electronic Properties of Nanoparticles

Single-electron tunneling in Au 55 cluster monolayers

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STM Investigations on Compact Au 55 Cluster Pellets

Cited by 52 publications

References 5 publications

Metal Clusters and Colloids

Metal Clusters and Colloids

Chemically Induced Metal-to-Insulator Transition inAu55Clusters: Effect of Stabilizing Ligands on the Electronic Properties of Nanoparticles

Single-electron tunneling in Au 55 cluster monolayers

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Product

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STM Investigations on Compact Au ₅₅ Cluster Pellets