Stuttgart 2012 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 8: Ion Trap and FT-ICR-MS, Molecules, Clusters and Reactions
MS 8.2: Invited Talk
Thursday, March 15, 2012, 14:30–15:00, V57.06
Light induced reactions (LIR) in a cold 22-pole ion trap — Oskar Asvany, Sandra Brünken, and •Stephan Schlemmer — I. Physikalisches Institut, Universität zu Köln
Ion molecule reactions play an important role in astrophysics and other plasma environments like planetary atmospheres. They are studied in a variable temperature 22-pole ion trap where the temperature dependence of the rate coefficient and thus related activation energies are determined. Reactions with competing product channels are of particular interest because the outcome often strongly depends on the internal states of the reaction partners. In the experiments described vibrational and/or rotational levels of the stored ions are excited by IR or FIR photons. The increase or decrease of the number of product ions monitored by mass spectrometry as a function of the excitation wavelength results in a very sensitive method of action spectroscopy of the parent ions. Examples include protonated hydrogen, H3+, the most abundant molecular ion in space, the very floppy CH5+ molecule or a radical like CH2D+. Experiments at low temperatures lead to simplified spectra and to significant changes in reactivity based on the population of particular states, an effect with significant consequences on the molecular composition of the interstellar medium.