Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.65: Poster

Tuesday, March 23, 2010, 18:30–21:00, Poster B1

Mechanics at the molecular scale: Insight into the physical mechanisms — •Olga A. Neucheva, Ruslan Temirov, and Stefan Tautz — Institut für Bio- und Nanosysteme (IBN-3) and JARA - Fundamental of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich, Germany

The manipulation of atoms and molecules is one of the problems under investigation in a surface science. The first successful attempt to transfer an atom from a surface with use of a scanning tunneling microscope has been realized by Eigler et al [1]. An interest to understand the underlying physical mechanism from both experimental and theoretical points of view has led to investigations of many systems which can be used as atomic and molecular switches [2,3]. In our work the behaviour of a single PTCDA molecule on Ag(111) has been investigated with a LT-STM. Two level fluctuations of the conductance of the junction have been observed within a narrow range of the tip heights and bias voltages. The bistability is related to reversible switching of one of the carboxylic oxygen atoms between the surface and the STM-tip. The current passing through the junction induces vibrations of the molecule leading to weakening and breaking of a chemical bond with the surface and establishing a new one with the tip and vice versa. The switching frequency strongly depends on the bias voltages and tip heights, following a non-linear dependence on the current.

[1] D.M.Eigler, C.P. Lutz, and W.E. Rudge, Nature 352, 600 (1991)

[2] J.A. Stroscio, and R.J. Celotta, Science 306, 242 (2004)

[3] S. Gao, M. Persson, and B.I. Lundqvist, PRB 55, 7 (1997)