Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 61: Nanostructures at Surfaces III
O 61.7: Vortrag
Mittwoch, 2. April 2014, 17:30–17:45, WIL B321
Ripening of truly monodisperse clusters under the STM — •Friedrich Esch1, Yves Fukamori1, Michael König1, Bokwon Yoon2, Bo Wang1, Uzi Landman2, and Ulrich Heiz1 — 1Technische Universität München, Catalysis Research Center, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748 Garching, Germany — 2School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
Matter in the non-scalable size regime displays unique, size-dependent chemical and physical properties. We study truly monodisperse supported clusters, i.e. with every cluster of same size and adsorption site and thus chemical environment. To this purpose, we soft-land size-selected PdN clusters on epitaxial, Moiré-structured graphene and boron nitride films.
The well-defined samples allow for studying ripening mechanisms at the atomic scale by Scanning Tunneling Microscopy (STM), by following the dynamics of individual clusters as well as the particle size distributions of ensembles of hundreds of clusters [1]. The cluster-substrate interaction determines which ripening mechanism holds, Ostwald or Smoluchowski ripening. It is shown periodically wettable substrates can be used to optimize cluster stability at elevated temperatures. Periodic wettability leads to apparent adsorption site crossovers at the ripening transition from clusters to nanoparticles.
[1] Y. Fukamori, M. König, B. Yoon, B. Wang, F. Esch, U. Heiz and U. Landman, Fundamental Insight into the Substrate-Dependent Ripening of Monodisperse Clusters, Chem. Cat. Chem. 5 (2013) 3330-3341