Hannover 2013 – wissenschaftliches Programm
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MS: Fachverband Massenspektrometrie
MS 3: Ion Trap and FT-ICR-MS, Molecules, Clusters and Reactions
MS 3.6: Vortrag
Montag, 18. März 2013, 18:00–18:15, F 442
The low-temperature nuclear spin (ortho/para) equilibrium of H3+ in collisions with H2 — •Florian Grussie1, Max Berg1, Kyle Crabtree2, Sabrina Gärtner3, Ben McCall2, Stefan Schlemmer3, Andreas Wolf1, and Holger Kreckel1 — 1Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg — 2Department of Chemistry, University of Illinois at Urbana-Champaign. Urbana, IL 61801, USA — 3I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln
The triatomic molecular hydrogen ion H3+ is the cornerstone of interstellar chemistry and the simplest polyatomic molecule. As a highly reactive proton donor, H3+ initiates the formation of larger interstellar molecules like water and hydrocarbons. Recent observations of H2 and H3+ in the diffuse interstellar medium revealed a difference in the nuclear spin excitation temperatures of the two species. In order to probe the nuclear spin exchange in the H3+/H2 reaction system, we have performed measurements of the steady-state ortho/para ratio of H3+ in collisions with thermal H2 in a temperature-variable cryogenic radiofrequency ion trap at the Max Planck Institute for Nuclear Physics [1]. The populations of the lowest rotational states of H3+ were probed by a laser-induced chemical reaction with argon. The product ArH+ of this chemical reaction can be detected with very high sensitivity. Here we present results for temperatures from 45-100 K and discuss the implications for the diffuse interstellar medium.
[1] F. Grussie et al. 2012, ApJ, 759, 21