Description
Ultracold ground-state molecular quantum gases and mixtures yield highly complex and mostly unknown scattering behavior. In molecule-molecule collisions it ranges from the formation of long-lived four-body complexes to subsequent chemical reactions [1], photo-excitation [2] or spontaneous spin relaxation [3]. Atom-molecule collisions can give rise to tunable interactions such as Feshbach resonances [4] and might be used for evaporative cooling of molecules or trimer formation.
Here, we present our investigations of collisions with ultracold bosonic and chemical stable $^{23}$Na$^{39}$K ground-state molecules. In the pure molecular gas we probe photo-induced loss of four-body complexes in chopped optical dipole traps. We find the lower limit of the complex lifetime to be much larger than the lifetime derived from RRKM theory. In mixtures of $^{23}$Na$^{39}$K ground-state molecules with dense $^{39}$K atoms in different spin states, we find spin dependent loss rates. For one particular state of the $^{39}$K atoms, we observe unexpected suppression of the loss rate of several orders of magnitude below the universal scattering limit.
We also present our approach for the detection of such collisional events and product particles by state-selective ionization and VMI mass spectrometry [5] for our ultracold $^{23}$Na$^{39}$K ground-state molecules.
[1] Science, 2019, 366, 6469, 1111-1115
[2] Phys. Rev. Lett., 2020, 124, 163402
[3] arXiv, 2021, 2110.07501
[4] Science, 2019, 363, 6424, 261-264
[5] Phys. Chem. Chem. Phys., 2020, 22, 4861-4874
| Presenter name | Kai Voges |
|---|---|
| How will you attend ICAP-27? | I am planning on in-person attendance |
