Hamburg 2009 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 16: Stossprozesse, Energietransfer 1
MO 16.2: Vortrag
Mittwoch, 4. März 2009, 14:45–15:00, VMP 6 HS-G
Molecular fragment excitation in cold electron collisions with polyatomic ions: new views through EMU — •M.B. Mendes1, H. Buhr1,2, D. Schwalm1,2, M.H. Berg1, D. Bing1, O. Heber2, B. Jordon-Thaden1, C. Krantz1, S. Menk1, O. Novotný1, S. Novotny1, D.A. Orlov1, A. Petrignani1, M.L. Rappaport2, T. Sorg1, J. Stützel1, J. Varju3, D. Zajfman2, and A. Wolf1 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Weizmann Institute of Science, Rehovot, Israel — 3Charles University Prague, Czech Republic
The dissociative recombination (DR) of a molecular ion and a low energy (few meV) electron, often yielding excited and chemically active fragments, is a very important process in cold and dilute ionised media. Event-by-event studies of the reaction are performed with cold ion and electron beams merged in a storage ring. Fragment momenta can be derived by coincidence imaging. However, the multichannel plate detectors used so far are insensitive to fragment masses. This limited the reaction analysis for many cases apart from simple diatomics. We present a new energy-sensitive multi-strip detector (EMU), able to identify fragment masses together with offering good position resolution. A wide range of applications opens with this device for the measurement of excitation energies of molecular products from polyatomic ions. Recent results were obtained for the DR of D3O+ and suggest that certain dissociation paths on the molecule’s potential energy surface are preferred. A further promising application is the measurement of accurate product branching ratios for interstellar chemical models.