Regensburg 2019 – scientific programme

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SYCZ: Symposium Czech Republic as Guest of Honor

SYCZ 1: Czech Republic as Guest of Honor

SYCZ 1.4: Invited Talk

Thursday, April 4, 2019, 11:15–11:45, H4

Tunneling microscopy on insulators provides access to out-of-equilibrium charge states — Laerte L. Patera, Fabian Queck, Philipp Scheuerer, and •Jascha Repp — Department of Physics, University of Regensburg, 93040 Regensburg, Germany

Scanning Tunneling Microscopy (STM) is a powerful tool for the investigation of individual molecules, being able to probe their orbitals with sub-molecular resolution [1]. However, the requirement of a conductive substrate strongly limits the accessible electronic transitions. Conversely, atomic force microscopy (AFM) can be extended to insulating substrates, providing structural and electrostatic information. However, electronic states are generally not accessible by AFM. Here, we exploit the single-electron sensitivity of AFM [2] in detecting electrostatic forces to establish a novel mode in scanning probe, in which an alternating current instead of a direct current probes the sample. Only a single electron per oscillation cycle of the AFM cantilever tunnels between tip and investigated structure back and forth, enabling operation in absence of any conductance of the underlying substrate. Our results unveil the effects of electron-transfer and polaron formation on the single-orbital scale [3]. References: [1] J. Repp et al., Phys. Rev. Lett. 94, 026803 (2005); [2] J. Klein et al., Appl. Phys. Lett. 79, 1828 (2001); [3] L. L. Patera et al., in press (2019).