Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 32: Poster: Solid-Liquid Interfaces

O 32.13: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster C

In Situ Study of Ferrocenylundecanethiol Conformations — •Nelli Kremer, Tim Lämmerzahl, and Eckart Hasselbrink — Universität Duisburg-Essen, Essen, Deutschland

Self-assembled monolayers (SAMs) of alkanethiols have been extensively studied as model systems. Many research groups have investigated the structures of the monolayer under ambient conditions. However, structural changes of monolayers on electrode surfaces in electrolyte solutions in comparison to those in air are expected, because of the interaction between the adsorbed molecules and the species in solution. Therefore SAMs with ferrocene-terminated alkanethiols are of great interest since the orientation of the monolayer can be controlled by the redox-active functional group. By applying a potential, the ferrocene group in the monolayer on a gold surface readily exchanges an electron with gold. Previous studies have shown that the angle between the alkyl chain and the normal to the electrode surface changes upon oxidation, while structural reorientation associated with the rotation of the ferrocene group occurs.

Our vibrational sum frequency spectroscopy setup, which provides a resonant narrowband infrared laser pulse for pumping and a broadband femtosecond IR visible pulse pair, enables us to suppress the nonresonant background, which arises due to the metallic surface, and study the intramolecular vibrational energy redistribution (IVR) of 11-Ferrocenylundecanethiol (FcC11) on gold as well as the change of IVR due to the potential-dependent reorientation.

Keywords: Sum frequency generation spectroscopy; Spectroelectrochemistry; Intramolecular vibrational energy redistribution; Alkanethiol monolayer