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O: Fachverband Oberflächenphysik

O 120: Focus Session: Nonequilibrium Electron Transfer Across Interfaces in Real Time

O 120.3: Hauptvortrag

Freitag, 20. März 2020, 11:15–11:45, TRE Ma

Dynamic non-linear multi-frequency analysis: investigating the electron-transfer theory — •Fabio La Mantia — Universität Bremen, Energiespeicher- und Energiewandlersysteme, Bibliothekstr. 1, 28359 Bremen, Germany

The possibility to study and analyze the frequency response of electrochemical systems in dynamic conditions has shown the powerful advantage over classic electrochemical impedance spectroscopy (EIS) to be not limited only to stable systems. This is achieved by superimposing to a slow changing perturbation (dc) a broadband multi-sine perturbation (ac), which can cover several decades of frequency. However, typically the design of the multi-sine allows recovering and collecting only the first order frequency responses, typically named dynamic impedance spectra, for example through fast Fourier-transform EIS (FFT-EIS) or dynamic multi-frequency analysis (DMFA). In doing so, the information on the temporal asymmetry of the electrochemical reaction, carried by the intermodulation between any two frequencies of the multi-sine, is lost and cannot be recovered. In this work, after defining the concept of dynamic intermodulation, the multi-sine perturbation signal is redesigned in order to allow recovering and analyzing it. Non-linear dynamic multi-frequency analysis (NL-DMFA) will be used for investigating the electron transfer reaction to a redox couple in solution. The dynamic impedance and intermodulation spectra will be used in order to extract information on the dependence of the symmetry coefficient on the electrode’s potential and its correlation to the Marcus theory of electron transfer.