Cold Atom-Ion Charge-Exchange and Internal Molecular-Ion Sympathetic Cooling in an Ion-Neutral Hybrid Trap

这项研究使用PI小组开发的创新混合离子中性原子粒子阱作为观察低能离子与激光冷却到接近绝对零度（~0.001开尔文）的原子的反应和碰撞的工具。 磁光阱（MOT）中的冷原子可以用来捕获原子或分子离子的样品，以研究在接近空间温度下的离子-原子相互作用。冷，捕获Na+和Ca+原子离子，和Na 2+分子离子与超冷钠（Na）原子的反应速率将被测量，以及交感碰撞冷却的速率，使用混合陷阱。 这项研究在技术上可应用于精密光谱学、基本常数、太阳系和星际介质中的天体物理过程、原子离子钟和量子计算。 离子中性混合阱结合了两个独立但空间重叠的同心阱：MOT和Paul射频离子阱。具体而言，该项目将涉及Na和Ca+之间的绝对电子交换速率常数的直接实验测量，研究其对碰撞能量和离子和/或原子激发态种群的依赖性。这些比率将与模拟进行比较。被捕获的Ca+离子的共振辐射吸收光谱将作为陷阱的温度探针进行研究，以及通过使用共振冷却碰撞而不是传统的激光冷却在陷阱内形成受限的离子库仑“晶体”的小晶格的可能性。在实验原子物理根据以前的NSF补助金和两个额外的博士学位。水平的学生希望在新的补助金下完成他们正在进行的论文研究。 一名本科物理数学专业的学生在上一次拨款期间从事模拟工作，还有两名硕士-海德堡大学的一级交换生，他们做了实验工作。 物理系本科生和研究生都参与了这个项目的独立研究工作。 学生接受原子和分子物理学基本实验技术的广泛教育：激光和碰撞冷却和高真空（类似于太空条件）的捕获，以及冷离子操纵，捕获，检测和激光光谱学。PI于2013年在巴西圣保罗大学圣卡洛斯校园举行的研讨会上就这种混合陷阱研究发表了特邀演讲，5位诺贝尔物理学奖获得者出席了研讨会。研究成果经常在出版物和地方、国家和国际会议上发表。

This research uses an innovative hybrid ion-neutral atomic particle trap developed by the PI's group as a tool for observing reactions and collisions of low energy ions with atoms cooled by lasers to near absolute zero temperature (~0.001 Kelvin). The cold atoms within a magneto-optic trap (MOT) can be used to refrigerate a co-trapped sample of atomic or molecular ions to study ion-atom interactions at temperatures approaching that of space. Cold, trapped Na+ and Ca+ atomic ion, and Na2+ molecular ion reaction rates with ultracold sodium (Na) atoms will be measured, as well as the rates of sympathetic collisional cooling, using the hybrid trap. The research has technical applications to precision spectroscopy, fundamental constants, astrophysical processes in the solar system and interstellar medium, atomic ion clocks and quantum computing. The ion-neutral hybrid trap combines two separate but spatially overlapped and concentric traps: a MOT and a Paul radiofrequency ion trap. Specifically, the project will involve direct experimental measurements of the absolute electron-exchange rate constant between Na and Ca+, investigating its dependence on collision energy and ionic and/or atomic excited-state populations. The rates will be compared with simulations. The resonance radiation absorption spectrum of trapped Ca+ ions will be investigated as a temperature probe of the trap as will the possibility of forming small lattices of confined, ionic Coulomb "crystals" inside the trap by using sympathetic cooling collisions, rather than traditional laser cooling.A graduate student completed his Ph.D. in experimental atomic physics under the previous NSF grant and two additional Ph.D. level students expect to complete their ongoing dissertation research under the new grant. An undergraduate physics-mathematics student worked on simulations during the previous grant, as well as two M.S.-level exchange students from the University of Heidelberg, who did experimental work. Both undergraduate and graduate physics students participate in independent study work on this project. Students receive a broad education in basic experimental techniques of atomic and molecular physics: laser and collisional cooling and trapping at high vacuum (conditions resembling those of space), as well as cold ion manipulation, trapping, detection and laser spectroscopy. The PI gave an invited talk on this hybrid trap research in 2013 at a symposium on the Sao Carlos campus of the University of Sao Paulo, Brazil, attended by 5 physics Nobel Laureates. Research results are frequently presented in publications and at local, national and international meetings.