Probing ultracold reaction with ion spectrometry

Advances in AMO techniques enabled the creation of ultracold samples of molecular species and opened opportunities to explore chemistry in the ultralow temperature regime. We report progress toward a detailed microscopic picture of molecules transforming from one species to another. So far, most studies of ultracold collisions rely on a loss-of-molecules signal. To extend such studies into the short-range where chemistry takes place, we combine the production of quantum-state-selected ultracold KRb molecules with ion mass and kinetic energy spectrometry, and directly observed KRb $+$ KRb reaction intermediates and products. Such direct detections allow further studies, including measuring the transient reaction intermediate lifetime, steering the reaction pathway with light, and investigating the product state distribution.