Abstract
Exploring and controlling inelastic and reactive collisions on the quantum level is a main goal of the developing field of ultracold chemistry. For this, the preparation of precisely defined initial atomic and molecular states in tailored environments is necessary. Here we present experimental studies of inelastic collisions of metastable ultracold Rb2 molecules in an array of quasi-1D potential tubes. In particular, we investigate collisions of molecules in the absolute lowest triplet energy level where any inelastic process requires a change of the electronic state. Remarkably, we find similar decay rates as for collisions between rotationally or vibrationally excited triplet molecules where other decay paths are also available. The decay rates are close to the ones for universal reactions but vary considerably when confinement and collision energy are changed. This might be exploited to control the collisional properties of molecules.
Highlights
Exploring and controlling inelastic and reactive collisions on the quantum level is a main goal of the developing field of ultracold chemistry
It is striking that the decay takes place in a step-wise fashion which, after B100 ms, gives way to a much slower exponential decay with a corresponding time constant of 41 s. This slow exponential decay is similar to the one we observe in a deep 3D optical lattice (Fig. 2a, inset), which is due to background gas collisions and spontaneous photon scattering[41]
We presented the experimental determination of reaction rates for deeply bound triplet molecular states
Summary
Exploring and controlling inelastic and reactive collisions on the quantum level is a main goal of the developing field of ultracold chemistry. Recent advances in the preparation of ultracold molecular samples in well-defined quantum states[1,2,3,4,5,6,7] sparked increasing interest in studying molecular collisions and chemical reactions on a pure and fundamental level[8,9,10,11,12] Such experiments were first carried out with highly excited molecules[13,14,15,16,17,18,19,20,21,22,23,24] ( in the context of Efimov physics25–30), which can vibrationally relax in a collision. These results are compared to predictions of a quantum defect model[39,40]
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