An improved time-of-flight method for cluster deposition and ion-scattering experiments

Turra, Mike; Waldschmidt, Benjamin; Kaiser, Bernd

doi:10.1063/1.2834874

Cited by 5 publications

(5 citation statements)

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“…In this paper an incident energy E i stands for the difference between the average kinetic energy of the projectile ions and the potential energy. Since the incident energy spread of the primary ion beam amounts to approximately 150 eV ͓full width at half maximum ͑FWHM͔͒, 16,19 fragmentation processes are already observed also for negative values of E i .…”

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Energetics and fragmentation of single-doped tin and lead clusters

et al. 2009

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The fragmentation behavior of the bimetallic cluster ions Sn N Pb + and Pb N Sn + has been investigated by tandem time-of-flight mass spectrometry in combination with density-functional theory. The low-energy surface-induced dissociation patterns of Sn N Pb + and Pb N Sn + with N =6-11 are dominated by the subsequent loss of atoms. For Sn N Pb + first the single lead atom is split off; in contrast the Pb N Sn + clusters dissociate mainly in fragments retaining the single tin atom, which is in full accordance with the quantum chemical results. For larger collision energies the complete set of smaller tin fragment ions Sn N−M + with M Ͻ N is found for Sn N Pb + , whereas the Pb N Sn + clusters decay into two series of Pb N−M Sn + and Pb N−MIn recent decades the properties of clusters became an interesting field of research because clusters allow someone to study the stepwise development of matter from the atom to the bulk. The structural and electronic properties of the group-14 clusters are of particular interest 1-6 because these systems permit someone to study whether the transition from covalent to metallic bonding, which takes place within this group in the bulk, manifests also in reduced dimensions. Additionally the potential of these clusters for applications in nanotechnology is particularly promising. However, not only are the pure element clusters are of interest but also doped or bimetallic cluster species 7-13 because the chemical and physical properties of doped or alloyed clusters may be tuned by varying the composition and the atomic ordering as well as the size of the clusters.For tin-lead nanoalloys it has been, for example, found that the solubility and the thermal-expansion coefficient depend sensitively on particle size. 14 This behavior has been attributed to a size-dependent cohesive energy. In order to better understand the influence of dopant atoms on the energetics of nanoalloys, we have investigated single-doped tin and lead clusters. In the present paper the surface-induced dissociation of tin-rich Sn N Pb + and lead-rich Pb N Sn + clusters with N =6-11 is analyzed to study the fragmentation behavior of the doped clusters because the unimolecular dissociation of clusters is very sensitive to the binding energies. 15 The comparison of the experimental results with quantum chemical calculations gives deeper insight into the energetics of the single-doped group-14 clusters. After a presentation of the experimental procedure, the results of our quantum chemical calculations will be discussed, followed by a detailed analysis of the experimental data in comparison with the theoretical predictions.An overview of the apparatus used for the present experiments is already reported in the literature. 16 Therefore, the experiment will be described only briefly.Bimetallic clusters are produced by a dual laser vaporization cluster source. The cluster source consists of two separate formation zones where homoatomic clusters are generated. These clusters were then transported with the carrier gas to a re...

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Energetics and fragmentation of single-doped tin and lead clusters

et al. 2009

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“…(A study of 3-D metal clusters as catalysts in CNT growth was reported in [8], however, no CNT growth was studied therein; CNT growth derived from nm-sized, ligand-stabilized mixed metal clusters as precatalysts was reported in [9]. ) Non-agglomerated naked iron clusters of 0.6–0.9 nm size were generated, mass-selected and surface-implanted at room temperature under ultrahigh vacuum [10] at a surface coverage in the range of a few thousandths up to a few hundredths of a monolayer on standard substrate grids for transmission electron microscopy (TEM). The kinetic energy of the as deposited iron clusters is about 2550 ± 150 eV, which is sufficient for their surface implantation [11].…”

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Generation and agglomeration behaviour of size-selected sub-nm iron clusters as catalysts for the growth of carbon nanotubes

Joshi¹,

Waldschmidt²,

Engstler³

et al. 2011

Beilstein J. Nanotechnol.

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SummaryMass-selected, ligand-free FeN clusters with N = 10–30 atoms (cluster diameter: 0.6–0.9 nm) were implanted into [Al@SiOx] surfaces at a low surface coverage corresponding to a few thousandths up to a few hundredths of a monolayer in order to avoid initial cluster agglomeration. These studies are aimed towards gaining an insight into the lower limit of the size regime of carbon nanotube (CNT) growth by employing size-selected sub-nm iron clusters as catalyst or precatalyst precursors for CNT growth. Agglomeration of sub-nm iron clusters to iron nanoparticles with a median size range between three and six nanometres and the CNT formation hence can be observed at CVD growth temperatures of 750 °C. Below 600 °C, no CNT growth is observed.

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“…A number of state-of-the-art cluster deposition instruments have been built for size-selected cluster science. The list is long, but some representative instruments are the Heiz instrument − and those located at EPFL, Switzerland, − the University of Utah, Salt Lake City, the Technische Universität Darmstadt, Germany, and the Universidad Autónoma de Nuevo León, Mexico . The listed instruments use quadrupoles in the mass selection stage.…”

Section: Instrumentation For Ion/surface Collision Experimentsmentioning

confidence: 99%

“…Preparation and physicochemical investigations of sized-selected clusters derived from various other metals have been reported: Al, Cu, , Si, W, Ni, ,,, Ru, Mo 4 S 6 , Mo n /(MoO 3 ) n , Met-Cars, and various bimetallic clusters. ,, …”

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confidence: 99%

“…Preparation and physicochemical investigations of sizedselected clusters derived from various other metals have been reported: Al, 408 Cu, 231,252 Si, 228 W, 409 Ni, 154,229,410,411 Ru, 250 Mo 4 S 6 , 251 Mo n /(MoO 3 ) n , 211 Met-Cars, 412 and various bimetallic clusters. 223,263,413 Although the results show potential value in catalysis, the challenging task of scaling up the production of size-selected clusters at surfaces for use as industrial nanocatalysts remains to be accomplished. DFT calculations predict high CO oxidation activity for ligand-protected subnanometer-sized Au clusters.…”

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confidence: 99%

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Low-Energy Ionic Collisions at Molecular Solids

et al. 2012

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Figure 2. Ion/surface collision spectrum recorded after collision of 30 eV benzene molecular ions at an H-SAM surface. The ion at m/z 91 corresponds to the addition of a methyl group followed by loss of H 2 and that at m/z 65 to further loss of C 2 H 2 . The peak at m/z 79 is due to a H atom abstraction reaction. The inset shows the collision process and some reaction products. Reprinted from ref 72.

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An improved time-of-flight method for cluster deposition and ion-scattering experiments

Cited by 5 publications

References 50 publications

Energetics and fragmentation of single-doped tin and lead clusters

Energetics and fragmentation of single-doped tin and lead clusters

Generation and agglomeration behaviour of size-selected sub-nm iron clusters as catalysts for the growth of carbon nanotubes

Low-Energy Ionic Collisions at Molecular Solids

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