Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 15: Scanning Probe Techniques: STM/AFM
O 15.5: Talk
Monday, March 16, 2015, 16:00–16:15, MA 043
3-D force and current mapping on PTCDA/Ag(111): the effect of inherent charge at the probe Xe atom — •Oleksandr Stetsovych1, Prokop Hapala1, Ondřej Krejčí1, Martin Ondráček1, Martin Švec1, and Pavel Jelínek1,2 — 1Institute of Physics, ASCR, Praha, Czech Republic — 2Graduate School of Engineering, Osaka University, Japan
The combination of STM and dynamic AFM with functionalized tips allows the investigation of structural and electronic properties of organic molecules with high resolution. In this work, we employ Kolibri sensor with Xe-functionalized tip to acquire simultaneous 3D maps of the force, tunneling current and dissipation over the PTCDA deposited on Ag(111). The detailed contrast features of the force maps at various tip-sample separations are compared to a numerical model. The model describes relaxation of the Xe atom on the probe due to Pauli repulsion and electrostatic interaction with the surface.
Moreover, we observe a specific contrast difference between two independent measurements with Xe-functionalized tips. With a support of the model, it is possible to attribute the varying contrast to an inherent charge on the Xe-atom probe. By a careful comparison of the experimental and simulated data, we can analyze the electrostatic forces acting between the tip and molecule.