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MO: Molekülphysik
MO 18: Stossprozesse, Energietransfer
MO 18.4: Talk
Thursday, March 25, 2004, 17:15–17:30, HS 355
Experimental Investigations of Radiative and Ternary Association for CH3+ + CO: Interstellar Implications. — •Alfonz Luca1, Gheorghe Borodi1, Radek Plašil2, and Dieter Gerlich1 — 1Fakultät für Naturwissenschaften, Technische Universität Chemnitz, 09126 Chemnitz — 2Department of Electronics and Vacuum Physics, Mathematics and Physics Faculty, Charles University, 180 00 Prague
Formation of certain molecules in interstellar clouds must be explained either by surface processes or by complex reaction schemes including radiative association followed by ion-electron recombination. A low temperature radio-frequency 22-pole ion trap has been used to study association of CH3+ + CO at low number of densities and temperatures from 80 K to 280 K. In pure CO gas the temperature dependence of the ternary rate coefficient has been determined as k3(T) = 1.8 × 10−25cm6s−1 (T / 300 K)−2.2. If helium is used for stabilizing the collision complexes a rate coefficient k3(T) = 1.7 × 10−25 cm6s−1 (T / 300 K)−1.5 has been obtained. At CO number densities below 1011 cm−3 radiative stabilization becomes dominant. The radiative rate coefficient has been determined at 80 K, kr = 6.9 × 10−13 cm3s−1. In order to study this reaction under conditions prevailing in dense interstellar clouds a loaded supersonic molecular beam has to be utilized and the trapped CH3+ ions have to be cooled not only in He but also in p-H2.