Hamburg 2009 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 3: Präzisionsmassenspektrometrie, Ionenfallen, FT-IZR-MS, Moleküle, Cluster III
MS 3.8: Talk
Monday, March 2, 2009, 18:00–18:15, VMP 8 R05
Cryogenic hydrogen ions and chemical probing spectroscopy in rf ion cages — •Max H. Berg1, Annemieke Petrignani1, Dennis Bing1, Holger Kreckel2, and Andreas Wolf1 — 1Max-Planck Institut fuer Kernphysik, Heidelberg D-69117 — 2Columbia University, New York, NY 10027, USA
Radio frequency ion cages in the 22-pole geometry are well established tools for confining molecular ions in an almost field-free space, providing distinctly lower ion micromotion than standard Paul traps. We are applying these devices for the cryogenic cooling of H3+ ions by He buffer gas down to the lowest rotational levels. H3+ plays an important role in astrophysical and technical hydrogen plasmas, and is also a benchmark for quantum mechanical calculations of rovibrational energy levels of polyatomic molecules. For rovibrational spectroscopy, the conventional absorption method is a cumbersome approach as densities are low and H3+ rovibrational transitions are weak. A much more efficient detection method adapted to the cold multipole traps is to probe photon absorption by laser induced chemical reactions. The reaction products are detected via a mass spectrometer with near unity efficiency. This method revealed in the latest measurements the weakest H3+ rovibrational transitions observed to date, accessing vibrational levels more than 1.6 eV above the ground state.