LE13164
- It is an elementary principle of chemistry that radicals, i.e. atoms or molecules with an unpaired electron orbiting their nucleus, are highly reactive, while closed-shell species, i.e. atoms and molecules where the electrons are all paired, are relatively stable. In this paper, atoms and ions are produced and confined at ultracold temperatures in a novel hybrid trap, dubbed the MOTION trap. By carefully monitoring the interaction of the ultracold atoms and ions in this trap, it is observed that at these ultracold temperatures closed-shell species can in fact be thousands of times more reactive than radicals. This role-reversal is found to be the consequence of the underlying quantum dynamics driving the chemical reaction, which are normally obscured at room temperature. Given that reactions of the type observed in this work are important for determining astrophysical processes and in planned hybrid atom-ion devices, this work highlights both the need for a renewed effort in laboratory astrophysics and fully-quantum chemical reaction calculations on a case-by-case basis to guide the next generation of atom-ion device design.
