Bimolecular chemistry at sub-microkelvin temperatures

Abstract

Advances in AMO techniques lead to the creation of ultracold samples of molecular species and opened opportunities to explore chemistry in the ultralow temperature regime. While many prior studies investigated how long-range forces influence ultracold reactions, we aim to extend the exploration into the short-range where chemistry actually takes place. To this end, we developed a new experimental apparatus that combines the production of quantum-state-selected ultracold molecules with ion mass and kinetic energy spectrometry. Using such an apparatus, we were able to probe the exchange reaction between ultracold potassium-rubidium (KRb) molecules in its entirety, detecting both the reaction intermediates and the products. Such direct signals allowed us to further investigate this reaction, and eventually gain control over its various aspects. This thesis will describe the identification of an unusually long-lived reaction intermediate and a direct measurement of its lifetime, steering the pathway of the reaction with light, and controlling the quantum state distribution of the reaction products via an external magnetic field. The techniques we have developed here open up the exciting possibility to understand and manipulate state-to-state chemistry in the ultracold regime.