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O: Fachverband Oberflächenphysik

O 17: Metal substrates: Adsorption of organic / bio molecules III

O 17.5: Vortrag

Montag, 14. März 2011, 18:15–18:30, TRE Phy

Dynamic Force Spectroscopy at a Single Molecule Junction — •Christian Lotze, Martina Corso, Gunnar Schulze, Katharina J. Franke, and Jose Ignacio Pascual — Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin

Recent Developments in Atomic Force Microscopy made it possible to probe not only electronic properties of single molecules and atoms on (conducting) surfaces but also acquiring information about forces in the pN regime simultaneously. Determination of the charged state of single metal atoms [1] or resolving the chemical structure of a molecule [2] are just some of the possibilities, opening a new field of scanning probe spectroscopy.

We utilize our tuning fork based LT STM/AFM in the well known qPlus design operated at 5K to do single molecule force spectroscopy combined with tunneling differential conductance measurements. With our STM tip we contact a functionalized polyarene molecule in one side and lift it up from the surface, while the other side remains attached to the substrate [3]. During lift up we observe sawtooth like features in the df spectra that allow us to determine potential barrier heights during the molecule pulling process.

[1] Leo Gross, et al., Science 324, 1428 (2009) [2] Leo Gross, et al., Science 325, 1110 (2009) [3] F. Pump, R. Temirov, O. Neucheva, S. Soubatch, S. Tautz, M. Rohlfing, G. Cuniberti, Appl. Phys. A 93, 335 (2008)