Skip to Content

Karin Öberg - Leiden Observatory

Wednesday, May 27 – 4:15-5:00PM

 

“Complex processes in simple ices – the role of UV light”

 

Ice formation and destruction underpin the chemical evolution during star formation. Their experimental simulation is thus a vital ingredient to evolve astrochemistry, while their deeper understanding is an exciting solid-state chemistry problem. UV light induces a variety of physical and chemical processes in astrophysically relevant ices. A number of these processes have recently been quantitatively investigated in the laboratory, starting with non-dissociative photodesorption of CO and N2 ice, followed by dissociative photodesorption of CO2 and H2O ice, and UV-induced chemistry in CH3OH-dominated ice mixtures. These investigations correspond directly to astrophysical problems: the desorption experiments to the presence of non-thermally desorbed gas in star-forming regions, and the chemistry one to the excess of gas-phase complex molecules close to protostars. From a chemical point of view, the experiments probe direct UV photodesorption mechanisms as well as diffusion and reaction properties of radicals inside of amorphous solids. Together with different levels of modeling and previous experimental investigations, the new studies have already revised the understanding of non-dissociative and dissociative desorption mechanisms, while further modeling of diffusion and reactions of radicals is on the way.

 

Related Reference(s):

K. I. Öberg, G. W. Fuchs, Z, Awad, H. J. Fraser, S. Schlemmer, E. F. van Dishoeck, and H. Linnartz, “Photodesorption of CO Ice,” ApJL, 662, L23-L26 (2007).

K. I. Öberg, H. Linnartz, R. Visser, and E. F. van Dishoeck, “Photodesorption of Ices. II. H 2O and D 2O," ApJ, 693, 1209-1218 (2009).

K. I. Öberg, S. Bottinelli, and E. F. van Dishoeck, “Cold gas as an ice diagnostic toward low mass protostars,” A&A, 494, L13-L16 (2009).