Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
PC Online Talk
Chair: Lukas Gierster

Thursday, January 28, 2021, 11:00 am
Martin Thämer
FHI Department PC
Vibrational Surface Spectroscopy of Liquid, Interfaces with Nanometer Depth Resolution
An important portion of chemical reactions in biology, heterogeneous catalysis, or electrochemistry exclusively happens at liquid interfaces. This selectivity originates from the special physical and chemical properties of these interfaces, which can largely deviate from the corresponding bulk properties. Despite decades of intensive research, our current understanding of such interfaces on a molecular level is still very limited and mainly based on results from theory, such as molecular dynamics simulations. Prominent but still unanswered questions concern e.g. the spatial extend of the interfacial region, which is given by the length scale of preferential molecular orientation, the altered strength of molecular interactions, and the role of electric fields which arise from surface potentials.
In this talk I will present a new experimental approach to address these questions by adding nanometer depth resolution to phase resolved vibrational Sum Frequency Generation (SFG) spectroscopy. In the first part of the talk the basic concept of the technique will be shown along with the underlying physics governing second order nonlinear light-matter interactions. In the second part the results of several measurements on model systems and on the highly relevant D2O-air interface are presented and discussed, which illustrate the accuracy of the method and give a promising perspective for future experiments.

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