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O: Fachverband Oberflächenphysik

O 124: Development of Novel Methods II

O 124.4: Vortrag

Freitag, 20. März 2020, 11:15–11:30, WIL C107

In-plane and out-of-plane nanomechanical characterization of HOPG at the atomic scale — •Anna Lisa Eichhorn and Christian Dietz — TU Darmstadt

Multifrequency atomic force microscopy enables high resolution imaging of flat surfaces such as HOPG down to the atomic scale. The technique is based on the simultaneous excitation and detection of two or more cantilever eigenmodes. Depending on the type of the oscillation modes (flexural, torsional or lateral), out-of-plane elastic and dissipative sample properties or the in-plane shear behavior can be analyzed. Here, a bimodal approach was developed where the second flexural eigenmode amplitude was used for the topographical feedback. Additionally, either the first torsional or the first lateral eigenmode was excited at a constant amplitude while the frequency shift was recorded. Using the described setup atomic resolution was achieved in both imaging channels at ambient conditions, yet in the flexural topography images only every second carbon atom could be resolved, resulting in a triangular appearance. This effect is a result of the Bernal stacking of graphite monolayers, leading to two distinguishable carbon atom sites. Mapping the torsional/lateral frequency shift, however, provided a more comprehensive image, resolving the complete hexagonal arrangement of the carbon atoms. We aim to study the change in nanomechanical properties originating from single defects artificially generated within the structure by oxygen plasma treatment.