SKM 2023 – scientific programme

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O: Fachverband Oberflächenphysik

O 97: Focus Session: Scanning Probe Microscopy with Quartz Sensors IV

O 97.8: Talk

Friday, March 31, 2023, 12:30–12:45, TRE Ma

Visualizing electrochemical interfaces with a qPlus sensor-based AFM/STM — •Andrea Auer, Bernhard Eder, and Franz Giessibl — Institute of Experimental and Applied Physics, University of Regensburg, Germany

Atomic force microscopy (AFM) that can be simultaneously performed with scanning tunneling microscopy (STM) modes using metallic tips attached to self-sensing quartz cantilevers (qPlus sensors) has advanced the field of surface science by allowing for unprecedented high spatial resolution under ultrahigh vacuum conditions. Applying a qPlus sensor, which offers simultaneous STM/AFM and seamless transitions in between, to the field of electrochemistry creates new possibilities to locally image both the 3D layering of the interfacial water and the lateral structure of the electrochemical double layer. In this work, a home-built AFM/STM instrument equipped with a qPlus sensor for operation under precise potential control in an electrochemical liquid cell is presented. The potential-dependent structural interface organization of the electrochemical double layer on both highly oriented pyrolytic graphite (HOPG) and Au(111) electrodes in acidic media is investigated by means of (simultaneous) AFM/STM imaging and force spectroscopy. We observe frequency shift oscillations as a function of the z-piezo distance, which correspond to the layering of the interfacial solvent molecules, where both the number of layers as well as their strength is highly dependent on the applied potential.