Quantum-state controlled reactive scattering at tunable collision energy

该项目旨在以前所未有的细节水平研究锂原子和亚稳氦原子（Penning和缔合电离）之间的反应性碰撞，对反应物进行完全的量子状态控制，并在从热到量子的精确可调碰撞能量范围内进行碰撞。为此，现有的由超音速、速度可调亚稳态光束源和超冷锂原子作为散射目标的磁光阱组成的装置将扩展为电子和磁量子态控制组件。为了达到低碰撞能量，将建立一个亚稳态氦原子的低温源，并将其与原子束减速机相结合。本研究中获得的实验结果不仅将揭示自旋极化和量子效应对该反应机制的影响，而且还将挑战当前从头算量子化学计算势能表面的准确性，以及在由几个部分波主导的能量体系中相关的量子动力学。

This project is aimed at studying reactive collisions between lithium atoms and metastable helium atoms (Penning and associative ionisation) at an unprecedented level of detail, with full quantum-state control of both reactants and at precisely tunable collision energies ranging from the thermal to the quantum regime. For this purpose, an existing setup composed of a supersonic, velocity-tunable metastable beam source and a magneto-optical trap for ultracold lithium atoms as a scattering target will be extended with components for electronic and magnetic quantum state control. To reach low collision energies, a cryogenic source for metastable helium atoms will be built and combined with an atomic beam decelerator. The experimental results obtained in this study will not only shed light on the influence of spin polarisation and quantum effects on the mechanism of this reaction but they will also challenge the current level of accuracy of ab initio quantum chemical calculations of potential energy surfaces and the associated quantum dynamics in an energy regime dominated by a few partial waves.