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Unveiling structures, chemistry and spectroscopic fingerprints of silica oxides at the interface with liquid water by coupling DFT-MD with SFG spectroscopy

Date: 2023-12-08
Time: 10:00
Venue: M253
Speaker: Marie-Pierre Gaigeot

Université Paris-Saclay


I will review our most recent theoretical works done by DFT-based molecular dynamics simulations (DFT-MD) on silica oxides at the interface with liquid water in synergy with SFG spectroscopy. We will show that the synergy of DFT-MD with the new experimental set-up of SFG spectroscopy that directly probes the surface of the oxide in the phonon range, has allowed us to uncover an unexpected reconstruction and surface chemistry of the silica oxide. We will show how the synergy between DFT-MD and experimental SFG has allowed us to show the existence of Si(5c)O- 5-coordinated silicon species at the silica surface instead of the well-known Si(4c)O- 4-coordinated silicon species as a function of increasing pH. With new theoretical SHG calculations extracted from our DFT-MD simulations, our investigation also demystifies the multimodal chemistry of aqueous silica discovered decades ago, bringing in new information that we believe is capable to radically modify our current understanding of the chemistry of the top-surface of oxides. Beyond these structural, chemical and spectroscopic results, we will also show briefly the new theoretical method that we currently develop in order to calculate SFG spectra from DFT-MD simulations at a much lower computational cost than the current state-of-the-art method from the literature.


Marie-Pierre Gaigeot, Professor at the University of Evry val d’Essonne—University Paris-Saclay in Paris, France. She has also been for several years Subject Editor in Chemistry for the Royal Society Proceedings A, a member of the ACS & SCF American (& French) Chemical Societies, APS American Physical Society, has been appointed recently at the Advisory board of Physical Chemistry Chemical Physics (PCCP), and is FRSC Fellow of the Royal Society of Chemistry.

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