Hannover 2010 – scientific programme
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MO: Fachverband Molekülphysik
MO 2: Collisions, Energy Transfer
MO 2.5: Talk
Monday, March 8, 2010, 15:00–15:15, F 142
Isomers in Space - Dissociative Recombination of 2HCN2H+ — •Mario B. Mendes1, Henrik Buhr2, 1, Oldřich Novotný1, Max H. Berg1, Dennis Bing1, Michael Froese1, Manfred Grieser1, Brandon Jordon-Thaden1, Claude Krantz1, Steffen Novotny1, Dmitry A. Orlov1, Annemieke Petrignani1, Julia Stützel1, Oded Heber2, Michael L. Rappaport2, Dirk Schwalm2, 1, Daniel Zajfman2, and Andreas Wolf1 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Faculty of Physics, Weizmann Institute of Science, Rehovot, Israel
Hydrogen cyanide (HCN) and its energetically higher lying isomer hydrogen isocyanide (HNC) play an important role in the chemistry of dense molecular clouds within the interstellar medium. Despite the fact that HNC is less stable than HCN, its abundance is of the same order of magnitude. In order to explain this unusual abundance ratio, it has been proposed that both isomers are formed with the same efficiency in dissociative electron-ion recombination of HCNH+. Although this hypothesis has been discussed for more than 35 years now, there is still no convincing experimental evidence.
We studied the dissociative recombination of DCND+ in a storage ring experiment at the TSR, Heidelberg, using a new mass-sensitive fragment imaging detector. Surprisingly, DCN/DNC is mostly produced in vibrationally excited states, well above the isomerization barrier. The final branching ratios are fixed by radiative relaxation. This presents the formation of the two isomers in a new light, supporting the assumption that both of them are produced in this process.