ChemInform Abstract: Metal Clusters: Between Atom and Bulk

Schumacher, Ernst; Blatter, Fritz; Frey, Martin; Heiz, U.; Rothlisberger, Ursula; Schaer, Martin; Vayloyan, Arthur; Yeretzian, Chahan

doi:10.1002/chin.198919336

Cited by 11 publications

(16 citation statements)

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“…A particularly sophisticated and advanced model systems are supsupported size-selected clusters ported, size-selected metal clusters, with a precision of designing a catalyst atom by atom [11]. The first experiments of synthesizing such well defined agglomerates in the gas phase were reported in the early 1980s' [12,13,14,15,16] and revealed particular properties for each cluster size. Using these well defined particles as heterogeneous catalyst materials was made possible only with significant development of the experimental means [17,18].…”

Section: Motivation For Cluster Catalysis and State Of Researchmentioning

confidence: 99%

Catalysis with Supported Size-selected Pt Clusters

Schweinberger¹

2014

Springer Theses

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Under ultra high vacuum conditions the electronic structure, adsorption properties and reactivity of two olefins on surfaces and Pt clusters were probed in the submonolayer range. With adsorbed trichloroethene a possible cluster-adsorbate induced change in the electronic structure and for ethene a low temperature, size dependent self-/hydrogenation was observed.In a collaborative approach, the Pt clusters were investigated under ambient pressure conditions. The clusters were characterized on local and integral level and tested towards temperature stability. Experiments in gas phase μ-reactors and in liquid, as part of a hybrid photo catalytic system, revealed size dependent reactivity.

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Section: Motivation For Cluster Catalysis and State Of Researchmentioning

confidence: 99%

Catalysis with Supported Size-selected Pt Clusters

Schweinberger¹

2014

Springer Theses

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“…The theory is that an isolated atom, or a few atoms linked together in a cluster as in a molecule, possess discrete electron levels, introducing a quantum-size effect. It has been shown indeed that the thermodynamic properties of a metallic cluster vary with the number of atoms n which it contains, in solutions (Delcourt and Belloni, 1973;Henglein, 1977) or in the vapor phase (Morse, 1986;Schumacher, 1988;Haberland, 1994).…”

Section: Introductionmentioning

confidence: 99%

Photography: enhancing sensitivity by silver-halide crystal doping

Belloni

2003

Radiation Physics and Chemistry

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The physical chemistry of the silver photography processes, exposure, development and fixing, is briefly summarized. The mechanism of the autocatalytic development by the developer of the clusters produced in silver bromide crystals during the exposure which is controlled by the critical nuclearity of these clusters was understood from pulse radiolysis studies. The effective quantum yield F eff of photoinduced silver cluster formation in silver halide microcrystals is usually much lower than the photoionization theoretical limit F theor ¼ 1 electron-hole pair per photon absorbed, owing to a subsequent very fast intra-crystal recombination of a part of the electron-hole pairs. In order to inhibit this recombination and favor the silver reduction by photo-electrons, the AgX crystals were doped with the formate HCO 2 À as a specific hole scavenger. First, the dopant scavenges the photoinduced hole, thus enhancing the electron escape from the pair recombination. Second, the CO 2 dÀ radical so formed transfers an electron to another silver cation, so that the F eff limit may be of 2Ag 0 per photon. This Photoinduced Bielectronic Transfer mechanism is strictly proportional to the light quanta absorbed and induces an exceptional efficiency for enhancing the radio-or photographic sensitivity insofar as it totally suppresses the electron-hole recombination. r

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“…The theory is that both an isolated atom and a group of atoms linked to one another in a cluster or a molecule possess discrete electron levels, introducing a quantum-size effect. Indeed, it has been shown that the thermodynamic properties of a metallic cluster vary with its nuclearity-the number of atoms ''n'' which it contains, in solutions (Delcourt and Belloni 1973;Henglein 1977), or in the vapor phase (Morse 1986;Schumacher 1988;Haberland 1994).…”

Section: Nanotechnologies: An Ancient Tradition?mentioning

confidence: 99%

Nanotechnology: from the ancient time to nowadays

2015

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While nanosciences and nanotechnologies appear as new concepts developed at the end of the twentieth century, we show that metallic nanoparticles have already been used since ancient times, in particular as colorant in the glass and ceramic industries. Moreover, a lot of natural nanomaterials are also present in the mineral, vegetal and animal worlds. Nevertheless, the breakthrough of nanotechnology has been permitted in the past few decades by the advent of apparatus allowing the manipulation and observation of the nanoworld. Indeed, nowadays, nanomaterials and nanoparticles are used for many applications in our daily life, such as in the fields of electronics, catalysis, optics, biology, and medicine. This article presents an overview about nanotechnologies, with applications from ancient times till the present.

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ChemInform Abstract: Metal Clusters: Between Atom and Bulk

Cited by 11 publications

References 0 publications

Catalysis with Supported Size-selected Pt Clusters

Catalysis with Supported Size-selected Pt Clusters

Photography: enhancing sensitivity by silver-halide crystal doping

Nanotechnology: from the ancient time to nowadays

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