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Home > EN > Job Opportunities > PhD 2017

PCMT — Ion selectivity at the surface of atmospheric aerosols

by Webmestre - published on

PhD Director: C. Toubin — D. Duflot

Sea spray aerosol (SSA), one of the most abundant naturally produced aerosols in the atmosphere, is mainly formed through the bubble bursting process in the open ocean. SSA chemically consists of organic matter and salts, whose relative ratios vary as a function of size. Recent efforts have identified saturated and unsaturated linear carboxylates (LCs) and various derivatives as well as linear dicarboxylates (LDCs) as components of the organic-­‐rich fraction of nascent SSA. Grassian et al.(1) have shown a selective enrichment of ions, organic and inorganic, at the air/water interface. This mechanism can be better understood through molecular level investigation. Electronic structure calculations will be first carried out to quantify the interactions between the organic surfactants, mono and dicarboxylates, and the inorganic ions. Moreover, classical and ab initio molecular dynamics simulation will also be employed to mimic explicitly the interface taking into account temperature and concentration effects. These calculations will allow to derive some trends on the surface concentrations of ions at the liquid− air interface compared to the aerosol phase.

Finally, the outcomes of the thesis will contribute to a better understanding of the ions distribution at the aerosol particle and the consequences for its reactivity. The proposed work falls within the scope of the CaPPA Labex (Chemical and Physical Properties of the Atmosphere), and more specifically into « Work Package 2 » (Aerosol microphysical, chemical and optical properties from fundamental heterogeneous processes to remote sensing), in which the PCMT group from PhLAM is involved.

(1) R. Cochran et al, J. Phys. Chem. Lett. 2016, 7, 1692−1696 (DOI: 10.1021/acs.jpclett.6b00489)