Even though Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous in the interstellar medium, the role they play as catalysts for interstellar chemistry is still not well understood. However, existing experimental data [1-3] and theoretical calculations [4] indicate that PAHs may well play a very active role, in particular in connection with the formation of molecular hydrogen. These findings may explain observations of increased molecular hydrogen formation rates in Photodissociation regions with high PAH abundances [5-6]. In my talk I will present temperature programmed desorption data demonstrating the formation of highly super-hydrogenated PAHs via hydrogen addition reactions and catalytic formation of molecular hydrogen via abstraction reactions at a wide range of H atom temperatures [1-3]. Approximate cross-sections for these reactions derived via model simulations will be presented [7]. The implications for the role played by PAHs in interstellar chemistry will be discussed. [1] J. D. Thrower, E. E. Friis, A. L. Skov, B. Jørgensen and L. Hornekær. Phys. Chem. Chem. Phys. 16, 3381 (2014) [2] J. D. Thrower, B. Jørgensen, E. E. Friis, S. Baouche, V. Menella, A. C. Luntz, M. Andersen, B. Hammer, and L. Hornekær. Astrophysical Journal 750, 1, (2012) [3] V. Menella, L. Hornekær, J. Thrower and M. Accolla. Astrophys. J. Lett. 745, L2 (2012) [4] E. Rauls and L. Hornekær. Astrophys. J. 679, 531 (2008) [5] E. Habart, F. Boulanger, L. Verstraete, G. P. des Fortes, E. Falgarone and A. Abergel, Astron. Astrophys. 397, 623 (2003) [6] E. Habart, F. Boulanger, L. Verstraete, C. M. Walmsley and G. P. des Forets, Astron. Astrophys. 414, 531 (2004) [7] A. L. Skov, J. D. Thrower and L. Hornekær. Faraday Discussions 168, 223 (2014)

Polycyclic aromatic hydrocarbons as catalysts for interstellar molecular hydrogen formation

249th National Meeting (2015)

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