Physics Colloquium, Henning Zettergren, Stockholm University
|When:||Th 16-05-2019 16:00 - 17:00|
|Title:||Free flying fullerenes and small graphene flakes in space|
|Date:||16 May 2019|
|Start:||16:00 (Doors open and coffee available at 15:30)|
To this date, a rich variety of molecular species have been identified free flying in the interstellar medium. Most of them contain fewer than ten atoms but there are also significantly larger ones.
Observations from the Hubble space telescope reported last month  combined with recent laboratory results [2,3], give solid evidence for the existence of fullerene molecules (C60) containing sixty carbon atoms arranged in a soccer ball shape. This means that we now know that they are out there, but how and where they are formed are still outstanding questions to be answered. It has for instance been suggested that fullerenes are formed by UV-processing of Polycyclic Aromatic Hydrocarbons , which can be regarded as small pieces of graphene sheets terminated by hydrogen atoms. Such PAHs are believed to make up about ten percent of the carbon in the universe, and thus to be key players in various astrophysical environments although no individual PAH has yet been identified . Laboratory experiments together with theory and model developments are essential to advance the understanding of how complex molecules are formed and may survive in space.
In this talk, I will discuss these key questions and highlight results from recent combined experimental and theoretical studies on how isolated free flying fullerenes and PAHs respond to light and energetic particles, and how they are affected by a surrounding (cluster) environment.
 M. A. Cordiner et al, The Astrophysical Journal Letters 875, L28 (2019).
 E. K. Campbell, M. Holz, D. Gerlich, and J. P. Maier, Nature 523 32 (2015)
 M. Kuhn et al, Nature Communications 7, 13550 (2016)
 O. Berné, G. Mulas, and C. Joblin, A&A 550, 4 (2013)
 A. G. G. M. Tielens, Annu. Rev. Astron. Astrophys. 46, 289 (2008) n.