OPOKU Richard Asamoah: Theoretical core spectroscopy of molecules interacting with ice surfaces.
PhD thesis: Ice is ubiquitous in the environment in the form of snow, sea ice, or cirrus clouds and can play an important role as a catalyst for reactions between atmospheric trace gases and trace gas scavenger. Uptake of oxygenated and halogenated molecules has been proposed for major atmospheric oxidation capacity. An experimental means of following the interaction between the molecular species and the substrate is via X-ray photoelectron spectroscopy (XPS) [1,2], one of the most sensitive probes for surface elemental composition. However, given the complexity of the physico-chemical processes that can occur, the analysis of such experiments is not trivial matter, and establishing a theoretical framework for the interpretation of experimental results. simulating XPS spectra under different conditions (temperature, concentration of the species etc.) is of great relevance. The goal of this thesis is such a framework, based on a multiscale approach that allows for the treatment of such large, complex systems with the highest possible accuracy. We have focus on the combination of classical molecular dynamics , previously employed to determine adsorption sites at the air / ice interfaces, and fully quantum mechanical embedded electronic structure calculations [4, 5], recently introduced for valence ionizations and that should be validated to the core spectra domain. Once successfully applied to model systems, the new approach will be applied to our experimental collaborators.  A. Křepelová, T. Bartels-Rausch, A. Brown, H. Bluhm, M. Ammann J. Phys. Chem. A 2013, 117, 401-409.  X. Kong, A. Waldner, F. Orlando, L. Artiglia, T. Huthwelker, M. Ammann, T. Bartels-Rausch, J. Phys. Chem. Lett. 2017, 8, 4757-4762.  A. Habartova, L. Hormain, E. Pluharova, S. Briquez, M. Monnerville, C. Toubin, M. Roeselova, J. Phys. Chem. A 119, 39 (2015), 10052-10059.  A. S. P. Gomes and C. R. Jacob, Annu. Rep. Prog. Chem. Sect. C: Phys. Chem. 2012, 108, 222  Y. Bouchafra, A. Shee, F. Real, V. Vallet, A. S. P. Gomes, Phys. Rev. Lett. 2019, 121, 266001
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Thesis supervisor: TOUBIN Céline
Co-directors: André SEVERO PEREIRA GOMES