Collisions of ultracold molecules in bright and dark optical dipole traps

July 05, 2021

What happens when two molecules collide with each other? This seemingly simple question remains unanswered in many cases. Specifically, when two molecules collide in such a way that chemical reactions are impossible due to energy and momentum conservation, one would expect that the molecules remain unchanged. However, despite of this, we have found ultracold NaK molecules disappearing after collisions in our experiments.

Hence the question is: Where do these molecules go? The most commonly believed hypothesis is that a transient four-atom complex that is formed in the collision can be long-lived enough to be excited by background light.

Using a new trapping technique that allows us to suppress the background light intensity by three orders of magnitude, we set out to demonstrate that without light absorption, molecules will no longer be lost in collisions, but surprisingly found that they still are. While we can not yet offer a complete solution for this unexpected discovery, it will certainly be a starting point for further investigation.

If you would like to read the whole article please visit Physical Review Research.

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