Düsseldorf 2007 – scientific programme
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MO: Fachverband Molekülphysik
MO 22: Cold Molecules I (gemeinsam mit Q)
MO 22.3: Talk
Tuesday, March 20, 2007, 11:15–11:30, 6B
A negative ion proton transfer reaction at extremely low temperatures — •Rico Otto, Jochen Mikosch, Sebastian Trippel, Christoph Eichhorn, Markus Debatin, Matthias Weidemüller, and Roland Wester — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg
Using a low-temperature 22-pole ion trap we have studied the reaction of NH2− with molecular hydrogen in the temperature interval from 300 down to 8 Kelvin. We access in this experiment the, for negative ions previously unexplored, temperature regime below 25 Kelvin. For NH2− + H2 we observe an unexpected decrease of the reaction rate coefficient at low temperatures, which is indicative of a very small reaction barrier. In this presentation we will present the new low-temperature 22-pole trap setup, the employed experimental scheme to obtain absolute reaction rate coefficients, and the measurements for the proton transfer from H2 to NH2−. We will then discuss the current status of the interpretation of the measured rate coefficient. In future experiments we will investigate in how far the temperature dependence of the studied proton-transfer reaction represents a general behaviour of negative ion reactions at low temperature.