Rotational-state resolved quantum dynamics of molecular anions in a low temperature ion trap

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We will investigate cold reaction dynamics of negative ions with specific emphasis on quantum state-specific effects in elementary reaction processes. This research is motivated by our recent breakthroughs of quantitatively measuring electron detachment from molecular anions at low rotational temperature and of observing an unexpected temperature-dependence of the reaction rate coefficient, indicative of an unknown energy barrier, for a negative ion reaction for temperatures down to 8 Kelvin. Our goal is to identify the general importance of quantum mechanical effects in negative ion reactions and to investigate how quantum effects are modified in larger molecules and in microsolvated molecular clusters. These experiments employ a multipole ion trap, which allows us to control the internal temperature of trapped ions by buffer gas cooling. We will specifically study absolute photodetachment and chemical reaction cross sections as a function of the rotational and translational temperature. These results will provide insight into the relevance of quantum-state specific effects for reactions of negative ions in atmospheric and interstellar environments. In particular, we will identify suitable candidates of negative ions that promise to be observable in interstellar molecular clouds.