Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 97: Scanning probe techniques: Method development II

O 97.8: Vortrag

Donnerstag, 15. März 2018, 17:00–17:15, MA 005

Evaluating the potential energy above a single molecule at room temperature with lateral force microscopy — •Alfred J. Weymouth, Elisabeth Riegel, Sonia Matencio, and Franz J. Giessibl — Universität Regensburg, Regensburg, Germany

One of the challenges of AFM, in contrast to STM, is that the measured signal includes both long-range and short-range components. The most accurate method for removing long-range components is to measure both on and off an adsorbate and to subtract the difference. [1] This on-off method, however, is challenging at room temperature due to thermal drift. By moving to a non-contact scheme in which the lateral component of the force interaction is probed, the measurement is dominated by short-range interactions. [2] We use non-contact lateral force microscopy (LFM) in the frequency-modulation mode and measure the local interaction above a PTCDA island grown on Ag/Si(111)-(√3×√3). Each molecule appears as a single feature. By fitting this feature to a model potential, we can extract the depth and width of the potential. As we move closer to the sample, we reach the range in which Pauli repulsion plays a role in our tip-sample interaction.

[1] Ternes et al., Phys. Rev. Lett. 106, 016802 (2011)

[2] Weymouth, J. Phys. Condens. Matter. 29, 323001 (2017)