Laboratory measurements on cold electron reactions with key species of interstellar chemistry using ion beams

在星际介质的化学网络中，涉及带电粒子（原子离子、多原子分子离子和电子）的二元反应是在远低于标准实验室条件的温度和密度下的关键驱动机制。为了获得和改善这些过程的实验室数据，事件与存储离子束的反应研究提出了低能量的离子和电子之间的复合反应，特别是。通过将单个反应产物的计数和多粒子碎裂的成像与冷光阴极电子束的使用相结合，这种研究在最近的工作中已经成功地实现。然而，对于冷离子化学过程，由于室温热辐射和太短的束存储寿命，它们受到限制。因此，建议在低温静电储存环CSR上实施该技术，这将通过离子束的低温冷却环境和更长的储存寿命为冷离子化学过程的研究提供更有利的条件。数据将获得解离重组的多原子分子离子与冷电子在大大减少初始旋转激发，不受室温下的热辐射，和双电子重组的较重的单电荷原子离子的高度激发的里德伯原子形成的灵敏度大大提高。该项目使CSR成为研究星际介质中离子化学的独特实验室。

In the chemical network of the interstellar medium binary reactions involving charged particles (atomic ions, polyatomic molecular ions and electrons) are crucial driving mechanisms at temperatures and densities much below standard laboratory conditions. In order to obtain and improve laboratory data on such processes, event-by-event reaction studies with stored ion beams are proposed on low-energy recombination reactions between ions and electrons in particular. By combining the counting of individual reaction products and the imaging of multiparticle fragmentation with the use of cold photocathode electron beams, such studies have been successfully realized in recent work. For cold ion chemistry processes, however, they hit limitations due to the room-temperature thermal radiation and too short beam storage lifetimes. It is hence proposed to implement the technique at the cryogenic electrostatic storage ring CSR, which will offer much more favorable conditions for the study of processes in cold ion chemistry through the cryogenically cooled surrounding of the ion beam and much longer storage lifetimes. Data will be obtained for dissociative recombination of polyatomic molecular ions with cold electrons at much reduced initial rotational excitation, unaffected by room-temperature thermal radiation, and for dielectronic recombination of heavier singly charged atomic ions with a strongly improved sensitivity for the highly excited Rydberg atoms formed. The project opens up CSR as a unique laboratory for the study of ion chemistry in the interstellar medium.