AFM investigations of Au55 clusters on various substrates

Feigenspan, Th.; Houbertz, R.; Hartmann, Uwe

doi:10.1016/s0965-9773(97)00085-8

Cited by 6 publications

(4 citation statements)

References 7 publications

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“…The latter clusters have been investigated by a variety of methods, including EXAFS spectroscopy [1], specific heat measurements [2], Mössbauer spectroscopy [3], atomic force microscopy [4], scanning tunneling spectroscopy [5,6] and many others. However one of the major questions -if these clusters can still be regarded as metallic systems or not -could not be answered clearly.…”

Section: Introductionmentioning

confidence: 99%

Symmetry-Break-Induced Variation Of Energy-Level Degeneracy Observed On Individual Molecules By Low-Temperature STM

Mautes¹,

Zhang²,

Hartmann³

2003

AIP Conference Proceedings

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Articles you may be interested inIdentifying site-dependent effects of an extra Co atom on electronic states of single Co-phthalocyanine molecule Abstract. In order to experimentally analyze the influence of a small symmetry break on the degeneracy of discrete energy levels we have carried out STM/STS investigations on triphenylphosphine molecules (P(C 6 H 5 ) 3 ) adsorbed to Au(111) surfaces. The measurements were performed with a variable-temperature UHV-STM which was operated at 6.5 K. From the experimentally obtained I(V) data the energy-level distribution is derived for individual molecules and a symmetryreduction-induced decrease of the level degeneracy can be observed in detail and compared with former results.

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Section: Introductionmentioning

confidence: 99%

Symmetry-Break-Induced Variation Of Energy-Level Degeneracy Observed On Individual Molecules By Low-Temperature STM

Mautes¹,

Zhang²,

Hartmann³

2003

AIP Conference Proceedings

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“…The two-shell compound Au 55 [P(C 6 H 5 ) 3 ] 12 Cl 6 exhibits particularly interesting optical and electronic properties. ,, An obvious question is to what extent these properties are determined by the ligand molecules and atoms. Although a variety of different experimental methods and theoretical approaches have been applied to characterize the cluster's structure and electronic properties, − it remained unclear whether the properties of the ligand-coated cluster deviate from those of the naked one and what the properties of the latter are. Earlier Mössbauer investigations indicated largely nonmetallic behavior in contrast to that of Pt 309 .…”

mentioning

confidence: 99%

Reduced Metallic Properties of Ligand-Stabilized Small Metal Clusters

2003

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Low-temperature ultrahigh-vacuum scanning tunneling microscopy was employed to analyze the electronic behavior of Au 55 clusters stabilized by [P(C 6 H 5 ) 3 ] 12 Cl 6 ligands. At 7 K, the actual arrangement of the C 6 H 5 rings of the ligand molecules could be imaged. Spectroscopic data reveal discrete energy levels with an average spacing of 170 meV that can be attributed to the Au 55 core. Additionally, characteristic charge-quantization phenomena were observed. Energy and charge quantization both support the view that the clusters consist of a metallic core extending slightly beyond the first close-packed shell of Au atoms.

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“…An additional aspect is that, upon investigating the properties of ligand-stabilized clusters on top of solid substrates, the influences of cluster-cluster as well as cluster-substrate interactions generally have to be taken into account. 8 One of the most intensely studied ligand-stabilized clusters is Au 55 , first synthesized by Schmid's group. 9 Due to the sufficiently small number of Au atoms the clusters exhibit strongly size-effect-dominated physical properties.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, it is evident that ligand-stabilized clusters do generally not exhibit the properties of the naked cluster core but involve a more or less significantly pronounced influence of the ligand shell on their overall physical and chemical properties. An additional aspect is that, upon investigating the properties of ligand-stabilized clusters on top of solid substrates, the influences of cluster−cluster as well as cluster−substrate interactions generally have to be taken into account …”

Section: Introductionmentioning

confidence: 99%

Direct Observation of the Thermal Decomposition of Ligand-Stabilized Clusters

et al. 2002

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Ligand-stabilized Au 55 clusters have been observed by scanning probe microscopy upon thermal decomposition on top of graphite and mica substrates. On highly oriented pyrolitic graphite as well as on mica the ligand shell exhibits a thermal decomposition at a temperature of about 390 K. This temperature well matches data obtained on cluster solutions and pallets. The ligand decomposition results under ultrahigh vacuum conditions in the formation of naked Au clusters. The in situ needle sensor studies show that, due to the high cluster mobility at elevated temperatures, bigger spherical Au aggregates are formed on the graphite substrate. In contrast, on the mica substrate, the naked Au clusters aggregate to form small uniform islands that are stable up to temperatures of more than 700 K. Bigger Au aggregates could only be formed upon pushing the clusters by the microscope's probe at elevated temperatures. The significant difference in the cluster decomposition and aggregation processes on graphite and mica is attributed to the influence of a strong cluster-substrate interaction, which is solely present for mica.

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AFM investigations of Au55 clusters on various substrates

Cited by 6 publications

References 7 publications

Symmetry-Break-Induced Variation Of Energy-Level Degeneracy Observed On Individual Molecules By Low-Temperature STM

Symmetry-Break-Induced Variation Of Energy-Level Degeneracy Observed On Individual Molecules By Low-Temperature STM

Reduced Metallic Properties of Ligand-Stabilized Small Metal Clusters

Direct Observation of the Thermal Decomposition of Ligand-Stabilized Clusters

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