Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 40: Poster Tuesday: Adsorption and Catalysis

O 40.7: Poster

Dienstag, 2. April 2019, 18:00–20:00, Poster D

A microscopy approach to investigating the energetics of small supported metal clusters — Barbara A J Lechner, Fabian Knoller, Alexander Bourgund, •Sebastian Kaiser, Ueli Heiz, and Friedrich Esch — Department of Chemistry & Catalysis Research Center, Technical University of Munich, Lichtenbergstr. 4, D-85748 Garching

We present examples of cluster dynamics observed via fast scanning tunneling microscopy (FastSTM). To that purpose, we have boosted the temporal resolution of our commercial STM up to 16 frames per second with a specially developed add-on electronics module [1], allowing us to match the frame rate to surface dynamics observed at elevated temperatures. On the example of small Pd clusters supported on a hexagonal boron nitride nanomesh on Rh(111), we observed a range of different dynamics [2]. Cluster diffusion within a nanomesh pore changes with adsorbate size: While atoms diffuse along the rim of the pore, a small cluster experiences a corrugation in the potential energy landscape and jumps between six sites around the pore center. The difference can be explained by the additional internal degrees of freedoms of a cluster. Furthermore, we monitored the reversible switching between two structural isomers of Pd clusters in situ.

[1] F. Esch, C. Dri, A. Spessot, C. Africh, G. Cautero, D. Giuressi, R. Sergo, R. Tommasini, G. Comelli, Rev. Sci. Instrum. 2011, 82, 53702.

[2] B. A. J. Lechner, F. Knoller, A. Bourgund, U. Heiz, F. Esch, J. Phys. Chem. C 2018, 122, 22569.