Hannover 2010 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 28: Poster: Cold Molecules

MO 28.9: Poster

Donnerstag, 11. März 2010, 16:00–18:30, Lichthof

Photodissociation and chemical probing spectroscopy of H₃⁺ — •Dennis Bing¹, M.H. Berg¹, H. Buhr^2,1, M. Grieser¹, C. Kranz¹, M.B. Mendes¹, S. Menk¹, S. Novotny¹, O. Novotný^1,3, D.A. Orlov¹, A. Petrignani¹, R. Repnow¹, T. Sorg¹, J. Stützel¹, X. Urbain⁴, and A. Wolf¹ — ¹Max-Planck-Institut für Kernphysik, Heidelberg — ²Weizmann Institute of Science, Rehovot, Israel — ³Columbia University, New York, USA — ⁴Université catholique de Louvain, Louvain-la-Neuve, Belgium

We present developments towards resonantly enhanced multiphoton dissociation (REMPD [1]) spectroscopy on cold H₃⁺ by (a) driving rovibrational excitation from the ground state towards the H₃⁺ dissociation limit near 4.4 eV and (b) establishing single photon dissociation of vibrationally excited H₃⁺ into the channel H₂⁺ + H. Rovibrational excitation spectroscopy of H₃⁺ was performed in a 22-pole RF ion trap, where the ions were cooled down to their lowest rotational states and then excited above the barrier to linearity (E>1.24 eV). Transitions up to the visible range (reaching E>2 eV) were scanned with a cw dye laser. The photodissociation of H₃⁺ was performed separately [2] in a collinear ion-laser-beam setup at the ion storage ring TSR using ion-source-excited H₃⁺ and pulsed Nd:YAG laser harmonics of 266 and 532 nm. An H₂⁺ signal from laser dissociation of stored H₃⁺ ions carrying about 3.4 eV internal excitation was seen with 266 nm and decayed with 1 ms lifetime after the ion beam injection. Combination in a REMPD scheme is coming into reach. [1] B. Roth et al., PRA 74, 040501(R); [2] A. Petrignani et al., J. Phys. Chem. A (submitted).