Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.3: Poster

Wednesday, March 25, 2009, 17:45–20:30, P2

Faceted Lead Clusters on Nano Structured HOPG — •Niklas Grönhagen, Farhad Ghaleh, and Heinz Hövel — Technische Universität Dortmund, Experimentelle Physik I, 44221 Dortmund

Lead as a cluster material shows an interesting behavior which distinguishes it from other metals. Lead starts diffusing at quite low temperatures and tends to form facets very easily. This is because Pb atoms can reorganize within or between clusters, consequently lowering their surface energy and thus transform into clusters with improved stability.

In the present study we produced faceted lead clusters by deposition of lead atoms on graphite (HOPG) samples, prestructured with nanometer sized pits [1]. The nano-pits were either distributed randomly on the sample or produced in an array using focussed ion beam lithography (ionLiNE system, Raith GmbH) [2].

Subsequently the clusters were investigated by scanning tunneling microscopy. We observed a fine structure in the height distribution given by Pb monolayer steps and an odd-even-oscillation. By measurements with scanning tunneling spectroscopy we were able to show that "Quantum Well States" are responsible for this growth behavior.

[1] H. Hövel, Appl. Phys. A 72, 295 (2001) [2] F. Ghaleh, R. Köster, H. Hövel, L. Bruchhaus, S. Bauerdick, J. Thiel, R. Jede: J. Appl. Phys. 101, 044301 (2007)