SurfaceScience21 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 97: Poster Session VII: Poster to Mini-Symposium: Molecular scale investigations of liquid-vapor interfaces II

O 97.4: Poster

Donnerstag, 4. März 2021, 10:30–12:30, P

Kinetics of Nano-Droplet Halide Emission from Salty Interfaces — •Philip Loche¹, Douwe J. Bonthuis², and Roland R. Netz¹ — ¹Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany — ²Institute of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria

Ozone is one of many atmospheric trace gases whose presence is crucial for sustaining life on earth. Most of the ozone is located in the stratosphere (12 km - 55 km) where it absorbs short-wave radiation from the Sun and thus protects living organisms from potentially fatal genetic damage. Ozone depletion especially in the arctic can lead to temperature changes and influence the Southern Hemisphere mid-latitude circulation. The ozone concentration in the lower atmos-phere is correlated with the halide concentration which is emitted from seawater.

Here, we use molecular simulations to study the kinetics of Cl- by the evaporation from the air-water interface. We show that the emission of ions is a 2-state process. First hydrated ions are emitted, forming water fingers with the surface up to a distance of ~2 nm from the Gibbs dividing surface. If ions overcome this distance, they lose their hydration shell after ~20 nanoseconds and distances of several μm. From the determined reaction rate coefficient of evaporation we obtain the total flux of chloride ions per year from the earth's ocean and estimate that it would take roughly 90 years until the current chloride concentration in the lower atmosphere is reached.