Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 19: Poster Monday: Scanning Probe Techniques 1
O 19.8: Poster
Monday, September 5, 2022, 18:00–20:00, P4
Grating Coupled Illumination with Image Recognition for Scanning Tunneling Microcopy under Highly Stable and Truly Localized Optical Excitation — •Georg A. Traeger1, Marlo H. Teichmann1, Benjamin Schröder1,2, and Martin Wenderoth1 — 1IV. Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 2Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
We present a versatile approach for a highly stable and localized optical excitation in a scanning tunneling microscopy (STM). Optical gratings on STM tips allow to excite a surface plasmon polariton (SPP), which travels to the tunneling junction and results in a highly confined optical excitation. Unfortunately, this technique comes with the drawback, that a much larger thermal load compared to the conventional direct illumination of the tunnel gap is introduced to the tip. This necessitates a high stability of the laser setup both in terms of long-term power stability and pointing[1]. The latter is limited by the mechanical decoupling of the STM from the environment, leading to independent movement of the microscope and the laser focus. We utilize an auto focus approach based on a CCD camera, which is aligned with the optical pathway of a fs-laser to achieve a active coupling between the laser and the STM. Studying ultrafast photo-currents in tunneling junctions we find that the new setup allows for STM operation under higly localized and background free illumination with a lateral resolution better than 2nm. [1] Kloth et al., Rev. Sci. Instrum. 87, (2016).