Controlled cluster condensation into preformed nanometer-sized pits

Hövel, H.; Becker, Thomas E.; Bettac, A.; Reihl, B.; Tschudy, M.; Williams, E. J.

doi:10.1063/1.364003

Cited by 92 publications

(76 citation statements)

References 17 publications

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“…When irradiated with fluorescent light, spherical Ag particles can reform into triangular nano-prisms, which could be used for multicolor diagnostic labeling [2]. In terms of its easy preparation, stable and well-defined structure, as well as its weak interactions with metals, highly oriented pyrolytic graphite (HOPG) surface has been extensively used as substrate for growth of Ag clusters (particles) from different forms of Ag [3][4][5][6][7][8], as driven by their great application potential in industrial chemical catalysis.…”

Section: Introductionmentioning

confidence: 99%

“…In most vapor deposition methods, Ag growth on HOPG usually proceeds via the three-dimensional Volmer-Weber mode, as established by STM [3,5,6,10] and SEM [4] observations, and by molecular dynamics simulations [9]. Small clusters are nucleated randomly on the substrate and then coalesced into large islands, due to high mobility of Ag atoms and stronger interaction among them (compared to the Ag-substrate interaction terraces are wide enough, cluster grouping could happen which creates small irregularly shaped groups of clusters.…”

Section: Introductionmentioning

confidence: 99%

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Controlled growth of uniform silver clusters on HOPG

Wang

et al. 2005

Ultramicroscopy

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Controlled growth of uniform silver clusters on HOPG

Wang

et al. 2005

Ultramicroscopy

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“…growth described above [7,8]. Those few analyses have been hampered by the unavailability of theory at a level sufficient to predict the basic energetics for metals on graphite, i.e.…”

mentioning

confidence: 99%

Determining whether metals nucleate homogeneously on graphite: A case study with copper

et al. 2014

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Abstract.We observe that Cu clusters grow on surface terraces of graphite as a result of physical vapor deposition in ultrahigh vacuum. We show that the observation is incompatible with a variety of models incorporating homogeneous nucleation and highlevel calculations of atomic-scale energetics. An alternative explanation, ion-mediated heterogeneous nucleation, is proposed and validated, both with theory and experiment. This serves as a case study in identifying when and whether the simple, common observation of metal clusters on carbon-rich surfaces can be interpreted in terms of homogeneous nucleation. We describe a general approach for making system-specific and laboratory-specific predictions. Introduction.The conditions under which solids grow on solid surfaces determine the structure, properties, and distribution of the grown material. One of the simplest-and most informative-growth scenarios is that in which single atoms impinge on a solid surface, then diffuse randomly and aggregate into clusters. This situation is informative because there can be a direct relationship between clusters' characteristics (e.g. number density and size distribution) and the energetics of individual processes (e.g. diffusion of atoms and cluster nucleation). However, there is a basic condition for applying this relationship: Nucleation and growth must occur on homogeneous (defect-free) surface regions. Usually, the experimental observation of clusters on low-index surface terraces is taken to be a strong indication that this condition is met.A timely example of solid-on-solid growth is that of metals on carbon-based solids, especially on graphene and graphite. This type of combination is important for major energy-related technologies involving catalysis [1] and electrochemistry [2,3], and also for the exploitation of carbon-based solids in magnetic or electronic devices [4,5]. There have been many studies of model systems, especially studies of transition metals on graphite. [6] In these studies, it has been very common to observe clusters of metals on the (0001) terraces of graphite [6]. However, only rarely have the clusters' characteristics been analyzed in relation to the mechanism or energetics of homogeneous nucleation and

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“…This simplification is justified, because previous observations demonstrate that major disagreements may be anticipated for particles smaller than 1 nm [14]. Furthermore, the resonance condition is only slightly influenced by variations of ε(ω) due to the reduced dimensions for nanoparticles in our range of interest [52].…”

Section: Single Particle Characterizationmentioning

confidence: 84%

Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

2012

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The morphology of small gold particles prepared by Volmer-Weber growth on sapphire substrates have been investigated by two different characterization techniques. First, by non-extensive atomic force microscopy (AFM) in combination with optical spectroscopy and modeling of the optical properties using a theoretical model, recently developed in our group. Second, by extensive transmission electron microscopy (TEM). Comparing the results obtained with both techniques demonstrate that for small gold nanoparticles within the quasistatic limit, the morphological properties can be precisely determined by an appropriate theoretical modeling of the optical properties in combination with simple AFM measurements. The apparent mean axial ratio of the nanoparticles, i.e., the axial ratio that corresponds to the center frequency of the ensemble plasmon resonance, is obtained easily from the extinction spectrum. The mean size is determined by the nanoparticle number density and the amount of deposited material, measured by AFM and a quartz micro balance, respectively. To extract the most probable axial ratio of the nanoparticle ensemble, i.e., the axial ratio that corresponds to the most probable nanoparticle size in the ensemble, we apply the new theoretical model, which allows to extract the functional dependence of the nanoparticle shape on its size. The morphological parameters obtained with this procedure will be afterwards compared to extensive TEM measurements. The results obtained with both techniques yield excellent agreement. For example, the lateral dimensions of the nanoparticles after deposition of 15.2 × 10 15 atoms/cm 2 of gold has been compared. While a mean lateral diameter of (13 ± 2) nm has been extracted from AFM, optical spectroscopy and modeling, a value of (12 ± 2) nm is derived from TEM.

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Controlled cluster condensation into preformed nanometer-sized pits

Cited by 92 publications

References 17 publications

Controlled growth of uniform silver clusters on HOPG

Controlled growth of uniform silver clusters on HOPG

Determining whether metals nucleate homogeneously on graphite: A case study with copper

Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

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