Synthesis of monodispersed model catalysts using softlanding cluster
Stéphane Abbet1, Ken Judai1, Laurent Klinger2,
and Ueli Heiz1,**
1University of Ulm, Institute of Surface Chemistry
and Catalysis, Albert-Einstein-Allee 47, 89069 Ulm, Germany; 2Ecole
Polytechnique Fédérale de Lausanne, CRPP, 1015 Lausanne,
Abstract: 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 Nin 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 Sin 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 Aun 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.
* Special Topic Issue on the Theme
of Nanostructured Advanced Materials
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