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Seminar by Thanja Lamberts: 'Influence of ice on interstellar surface chemistry: Insights from computational studies' (Lecture)

Date
Monday 10 February 2020Add to my calendar
Time
from 14:00
Location
HG00.307
Speaker
Thanja Lamberts - Leiden Institute of Chemistry
Description

The darkness readily observed between the stars on a clear night sky is far Thanja Lambertsfrom empty. In fact, a large variety of molecules has been detected in the gas phase. They make up about 99% of the total mass in the Interstellar Medium (ISM). The final 1% of mass in the ISM is brought about by dust grains that once were expelled by dying stars.

I focus primarily on the cold, dense molecular medium where surface reactions lead to the build-up of ‘dirty’ ices leading to a solid-state molecular mantle covering the micron-sized dust grains. The composition of this mantle in turn influences the surface chemistry of most other species that are formed in situ. Species accrete, diffuse, and react on the surface after which they can evaporate back into the gas phase. The interplay between these processes determines which molecules are formed, where, and if they are astronomically observable, either in the solid or gas phase. Confirmation or exclusion of reaction pathways is possible experimentally, however, it is nearly impossible to quantitatively disentangle the relative importance on realistic amorphous ices.

By computational studies of each process individually I aim to provide coarse-grained astrochemical models with crucial input parameters, such as branching ratios, binding energies, rate constants, and energy dissipation efficiencies. To this end I make use of a variety of methods from theoretical and computational chemistry, ranging from force field-based solid-state descriptions to high-level coupled cluster theory of isolated reactions.

Contact
Prof. Herma Cuppen