Stuttgart 2012 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 8: Ion Trap and FT-ICR-MS, Molecules, Clusters and Reactions

MS 8.4: Vortrag

Donnerstag, 15. März 2012, 15:15–15:30, V57.06

Electron auto-detachment of excited SF₆⁻ — •Sebastian Menk¹, Klaus Blaum¹, Swarup Das², Michael Froese¹, Michael Lange¹, Manas Mukherjee², Robert von Hahn¹, Dirk Schwalm^1,3, Robert von Hahn¹, and Andreas Wolf¹ — ¹MPI für Kernphysik, 69117 Heidelberg — ²Raman Center for AMO Science, IACS, Kolkata 700 032 — ³Weizmann Institute of Science, Rehovot, 76100, Israel

Electron auto-detachment of excited SF₆⁻ has been investigated using the Heidelberg cryogenic electrostatic ion beam trap (CTF), where ions can be confined as a beam at keV energies and a time-dependent decay signal is gained by detecting neutralized fragments which escape from the trapping region. The cryogenic conditions provide extremely high vacuum and accordingly low background rates. Hence, they offer the possibility to observe this decay, in principle, over minutes. For the initial auto-detachment stemming from the SF₆⁻ excitation in the ion source, we followed its rate until it naturally vanished at ∼100 ms after ion injection. This enabled us to observe for the first time its fall-off from the previously seen power-law behavior. By detailed modeling of the vibrational auto-detachment, this fall-off is found to reflect the detachment threshold and the rotational excitation, with the power-law separately representing the vibrational excitation in the ion source. Corresponding excitation temperatures could be inferred. Over the longer storage time scale uniquely accessible at the CTF, studies of the same process following laser excitation are in preparation.