Imaging size-selected silicon clusters with a low-temperature scanning tunneling microscope

Messerli, Stéphane; Schintke, Silvia; Morgenstern, Karina; Sánchez, A.; Heiz, Ueli; Schneider, W. D.

doi:10.1016/s0039-6028(00)00722-6

Cited by 51 publications

(38 citation statements)

References 45 publications

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“…Furthermore, lateral displacement of the silicon clusters with the STM tip and subsequent imaging of the surface at the impact position revealed no damage at the atomic scale. Consequently, these experiments demonstrate the feasibility of obtaining supported monodispersed metal clusters at low support temperature (90 K) [42].…”

Section: Imaging Size-selected Silicon Clusters On Ag(111)mentioning

confidence: 62%

“…Softlanding of mass-selected Si 30 and Si 39 clusters on Ag(111) was observed in recent low-temperature STM experiments [42] performed at kinetic energies well below the softlanding limit and without raregas buffer layers. In these studies, the following findings point toward a nonfragmenting deposition of the clusters.…”

Section: Imaging Size-selected Silicon Clusters On Ag(111)mentioning

confidence: 70%

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Synthesis of monodispersed model catalysts using softlanding cluster deposition

Abbet

Judai

Klinger

et al. 2002

Pure and Applied Chemistry

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In nanocatalysis, clusters deposited on solid, well-defined surfaces play an important role. For the detection of size effects it is, however, important to prepare samples consisting of deposited clusters of a single size, as their chemical properties change with the exact number of atoms in the cluster. In this paper, the experimental tools are presented to prepare such model systems. The existence of monodispersed clusters is confirmed by various experimental findings. First, the carbonyl formation of deposited Ni n clusters shows no change in the nuclearity when comparing the size of the deposited clusters with one of the formed carbonyls. Second, scanning tunneling microscopy (STM) studies show that fragmentation of Si n clusters upon deposition can be excluded. In addition, the adsorption behavior of CO on deposited Pd atoms points to the existence of single atoms on the surface. Furthermore, CO oxidation results on Au n clusters confirm the existence of monodispersed clusters trapped on well-defined adsorption sites. Finally, we use Monte-Carlo simulations to define the range of clusters and defect densities, for which monodispersed clusters can be expected.

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Section: Imaging Size-selected Silicon Clusters On Ag(111)mentioning

confidence: 62%

Section: Imaging Size-selected Silicon Clusters On Ag(111)mentioning

confidence: 70%

Synthesis of monodispersed model catalysts using softlanding cluster deposition

Abbet

Judai

Klinger

et al. 2002

Pure and Applied Chemistry

Self Cite

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“…Recently, size-selected Si (111) surface, and at room temperature these clusters have been found to be mobile and they condense at step edges [44]. However, from this study it is not clear whether the clusters have merged to larger silicon particles or not.…”

Section: Deposition Of 'Magic' Silicon Clustersmentioning

confidence: 63%

Deposition of mass-selected cluster ions using a pulsed arc cluster-ion source

Klipp

Grass

Müller

et al. 2001

Applied Physics A: Materials Science & Processing

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Abstract.A PACIS (pulsed arc cluster-ion source) developed for high average cluster-ion currents is presented. The performance of the PACIS at different operational modes is described, and the suitability for cluster-deposition experiments is discussed in comparison with other cluster-ion sources. Maximum currents of mass-selected cluster ions of 3-6 nA of small Si The preparation of nanostructures on surfaces is one of the major tasks in technology and basic research. Applications of nanostructured surfaces are abundant and cover a wide range from heterogeneous catalysis to high-density computer memories. From the point of view of basic research, many of the properties of small three-dimensional nanostructures and two-dimensional islands on surfaces are not well understood yet. For example, there is no systematic study of the size-dependence of the electronic structure of clusters of simple metals on surfaces, although free clusters of such metals show strong variations depending on the number of delocalized electrons [1]. Concerning the chemical properties, there are first results on the size-dependence of the catalytic properties of small clusters on inert substrates [2], but there are only very few systematic studies yet (see below). The kind of research focussing on the electronic and chemical properties of monodispersed small clusters on surfaces is only at its beginning. The reason is that it is difficult to deposit clusters with a perfectly monodispersed size distribution on a surface.

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“…The structural reordering with decreasing Cu island size is thus directly reflected in the energetic position of the image potential state. Consequently, this experiment offers the intriguing possibility for the local determination of the atomic density of nanostructures that cannot be resolved atomically, e.g., facets of size-selected nanoclusters [40].…”

Section: -3mentioning

confidence: 99%

Quantitative determination of a nano-object's atom density without atomic resolution

et al. 2014

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We outline a possibility to determine the adatom density of individual nano-objects via measurement of their electronic structure. For this aim, the nonlinear shift of image potential states measured on individual Cu nanoclusters on Ag(100) by low-temperature scanning tunneling spectroscopy is carefully analyzed. The quantitative analysis is confirmed by density-functional theory calculations. A peak width analysis furthermore reveals whether the clusters are purely metallic or alloyed. For nanotechnology a structural control on the nanoscale is essential, because the physical as well as chemical properties of nanoscale objects depend on the exact arrangement of their atoms [1]. As a first step, it is of vital importance for scientists and engineers to resolve the internal structure of the nanosystems to understand and, in a subsequent step, tune the resulting macroscopic properties. The atomic structure of nanoparticles can be determined directly by scanning transmission microscopy (STEM) with high resolution down to 50 pm [2], which shows a two-dimensional projection of the crystal in some high-index direction of particles. With STEM, nanoparticles were imaged three dimensionally [3]. Even single defects within nanoparticles were identified recently [4]. Due to the width of the electron beam, the extraction of the data demands sophisticated procedures.For two-dimensional nanoparticles on surfaces, scanning tunneling microscopy (STM) turned out to be a simple and versatile tool for high resolution imaging. However, atomic resolution is often impossible for discrete entities consisting of only a few atoms, in particular for nanoclusters. These objects have the tendency to be moved or restructured at the tunneling parameters necessary for atomic resolution. On the other hand, structural information of a metal surface is clearly reflected in the energetic positions of its image potential states [5,6]. A Rydberg-like series of these states emerges, when an outside charge polarizes a metal surface and is attracted to the induced polarization charge. As the energy levels of these states are pinned to the vacuum level, they are closely related to the work function, which in turn varies with both the chemical composition of the surface and the surface orientation, and thus with atom density. Surface averaged values of energy, dispersion (and lifetime) of image potential states were extensively probed, first by inverse photoemission (IPES) [7] and later by two-photon photoemission spectroscopy (2PPE) [8]. High spatial resolution of an image potential state was achieved by scanning tunneling spectroscopy (STS) [9,10] . The shifts are consistent with a lateral confinement of the electrons as described by textbook (two-dimensional) particle-in-a-box models [14]. Such an assignment assumes atomically flat islands with perfect coordination, though a relation to potential relaxation or reconstruction of the latter has not been made so far [16]. In this article, we present a method for the analysis of metallic nanostructures ...

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Imaging size-selected silicon clusters with a low-temperature scanning tunneling microscope

Cited by 51 publications

References 45 publications

Synthesis of monodispersed model catalysts using softlanding cluster deposition

Synthesis of monodispersed model catalysts using softlanding cluster deposition

Deposition of mass-selected cluster ions using a pulsed arc cluster-ion source

Quantitative determination of a nano-object's atom density without atomic resolution

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