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O: Fachverband Oberflächenphysik

O 27: Poster Session II: Poster to Mini-Symposium: Molecular scale investigations of liquid-vapor interfaces I

O 27.4: Poster

Monday, March 1, 2021, 13:30–15:30, P

Probing the Gold/Water Interface with Surface Specific Spectroscopy — •Stefan Piontek, Stephanie Sanders, Dennis Naujoks, Alfred Ludwig, and Poul Petersen — Ruhr Universität, Bochum, DE

Water is integral in electrochemistry, in the generation of the electric double layer, and propagating the interfacial electric fields; yet our molecular-level understanding of interfacial water near functioning electrode surfaces is limited.

Sum-frequency-generation (SFG) spectroscopy offers an opportunity to investigate the structure and dynamics of the solvent near working electrochemical interfaces, as the method is inherently surface-specific. Previous attempts which propagated IR beams through the solvent have suffered due to the IR absorption of water. Furthermore, sending visible and IR beams through standard electrode films obscures the SFG spectra, due to the large nonlinear response of conduction band electrons.

To overcome this limitation, we have investigated thin yet conductive gradient sputtered Au films on CaF2 using SFG, FTIR, AFM, and UV-Vis spectroscopies to explore the ideal thickness of an Au electrode layer. SFG spectra of dry and wet 8.0-0.4 nm thick Au films suggest that unobscured interfacial water spectra can be obtained using Au films with a thickness of ~2 nm or less. With the newfound ability to probe interfacial solvent structure at electrode/aqueous interfaces we hope to provide insights into more efficient electrolyte composition and electrode design.