Hannover 2016 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 19: Posters 4: Novelties in Molecular Physics: Femtosecond Spectroscopy, Molecular Clusters, Cold Molecules and Helium Droplets
MO 19.19: Poster
Donnerstag, 3. März 2016, 16:30–19:00, Empore Lichthof
Thermalization of OH− in Multipole RF-Ion Traps with cold He, H2 and HD as buffer gas — •Gerhard Egger, Seunghyun Lee, Olga Lakhmanskaya, Eric Endres, Daniel Hauser, and Roland Wester — Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Österreich
High order multipole ion traps are a versatile tool for performing spectroscopy on cold molecular ions and analyzing cold ion-neutral reaction dynamics with astrophysical relevance. In contrast to a Paul trap, the linear 22-pole trap features a large field free region [1]. Cooling is achieved by collisions with neutral buffer gas, thermalizing the kinetic temperature as well as the internal degrees of freedom which works well for many ion species. Furthermore, the temperature can be tuned from several Kelvin to room temperature, which enables temperature dependent measurements of reactions. With rotationally resolved near threshold photodetachment of OH− the rotational temperature can be determined [2].
Interestingly, below 20 K the rotational temperature does not decrease linearly any more even though the trap temperature is reduced [2]. This can not easily be explained by the known heating effects. Therefore further measurements at different temperatures have been performed. Clearly seeing the effect in He buffer gas we performed corresponding measurements also in H2 and HD. These results will be presented.
[1] R. Wester, J. Phys. B 42, 154001 (2009) [2] R. Otto et al, Phys. Chem. Chem. Phys. 15, 612 (2013)