Stuttgart 2012 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 13: Poster 1: Cold Molecules, Femtosecond Spectroscopy, Molecular Dynamics
MO 13.11: Poster
Dienstag, 13. März 2012, 16:30–19:00, Poster.IV
High-resolution LIR-spectroscopy of molecular ions — •Oskar Asvany, Sandra Brünken, Lars Kluge, Sabrina Gärtner, and Stephan Schlemmer — I. Physikalisches Institut, Universität zu Köln
Laser Induced Reaction (LIR) is a powerful technique for the spectroscopy of molecular ions as well as the study of state-specific rate coefficients. It is based on trapping mass-selected ions in a cryogenic ion trap and probing their laser-induced excitation by the outcome of an endothermic ion-molecule reaction. In particular, the combination of cold ions with a narrow-bandwidth optical parametric oscillator (OPO) enables highly accurate determination of rovibrational transitions. In this poster, the application of this technique to H3+, CH2D+ and CH5+ in the 3 micron wavelength region is presented. H3+ and CH2D+ are molecules of mostly astrophysical interest. For CH2D+, the presented method yielded rovibrational lines known with MHz accuracy. A standard asymmetric rotor model fitted to the data transferred this acuracy to the ground state rotational transitions. The method demonstrated here could be a useful way to determine rotational transitions which are difficult to measure in the microwave region. The ion CH5+ is known to be the prototype of a floppy molecule. For this reason, its chaotic spectrum presented by Takeshi Oka in 1999 is still unexplained. Applying the LIR-technique, the prospects of obtaining high-resolution information of CH5+ are discussed. In this particular case, cooling of this floppy ion to populate only the lowest states will be crucial for the feasibility of the experiment.