The rich internal structure and strong long-range interactions available with molecules are a central motivation for ongoing efforts in molecular cooling, with applications envisioned in ultracold chemistry, precision spectroscopy, and quantum simulation. However, the molecular structure complicates many attempts to apply direct laser cooling. We present a scheme for cooling paramagnetic molecules solely through collisional processes, with the aim of providing a route applicable to many species, including naturally occurring ones. Starting from a supersonic source, we adiabatically decelerate cold molecules to a stop using co-moving magnetic traps. We then load the molecules into a tunable, static trap made of a high-Tc superconducting wire, and hold them for over a minute.
We achieve a collision rate that is sufficiently high to observe losses resulting from collisions between cold, trapped oxygen molecules, and differentiate between the relative contributions of elastic and inelastic collisions. The combination of a high collision rate and a long trapping time of our cold sample is a prerequisite condition for evaporative cooling.
Making use of the generality of this method, we now hope to identify a molecular species with suitable collisional properties and to cool it to quantum degeneracy.