Collisions of Spin-polarized YO Molecules in a Crossed Dipole Trap.

Gray Molasse Cooling inside a crossed dipole trap prepares YO molecules in the microkelvin regime, resulting in the highest phase space density of 1.8 * 10^-5 for a bulk laser-cooled molecular sample. This sets the stage to study YO-YO collisions, enabling the determination of state-dependent single partial wave two-body loss rates. We identify the partial wave contributions, specifically of the s-wave and p-wave, in specific rotational states. This is achieved by comparing loss rates across different spin mixtures or by tuning the collisional kinetic energy relative to the p-wave barrier.