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

我们将研究负离子的冷反应动力学，特别强调在基本反应过程中的量子态特异性效应。这项研究的动机是我们最近在低旋转温度下定量测量分子阴离子的电子脱离和观察到一个意想不到的温度依赖的反应速率系数，表明一个未知的能量屏障，温度低至8开尔文的负离子反应。我们的目标是确定量子力学效应在负离子反应中的一般重要性，并研究量子效应如何在大分子和微溶剂化分子簇中被修饰。这些实验采用了多极离子阱，使我们能够通过缓冲气体冷却来控制被捕获离子的内部温度。我们将专门研究绝对光剥离和化学反应截面作为旋转和平移温度的函数。这些结果将为大气和星际环境中负离子反应的量子态特定效应的相关性提供见解。特别是，我们将确定在星际分子云中有望观察到的负离子的合适候选者。

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.