Sympathetic cooling of polyatomic molecules with S-state atoms in a magnetic trap

TL;DR

This study demonstrates that polyatomic molecules can be sympathetically cooled and trapped magnetically using current technology, based on quantum scattering calculations showing slow spin relaxation rates.

Contribution

It provides a theoretical framework showing the feasibility of cooling and trapping polyatomic molecules with S-state atoms in magnetic traps.

Findings

Collision-induced spin relaxation occurs at slow rates.

Cryogenic buffer-gas cooling of polyatomic molecules is feasible.

Sympathetic cooling with alkaline-earth atoms may produce ultracold polyatomic gases.

Abstract

We present a rigorous theoretical study of low-temperature collisions of polyatomic molecular radicals with ^1S_0 atoms in the presence of an external magnetic field. Accurate quantum scattering calculations based on ab initio and scaled interaction potentials show that collision-induced spin relaxation of the prototypical organic molecule CH_2(X^3B_1) (methylene) and nine other triatomic radicals in cold 3He gas occurs at a slow rate, demonstrating that cryogenic buffer-gas cooling and magnetic trapping of these molecules is feasible with current technology. Our calculations further suggest that it may be possible to create ultracold gases of polyatomic molecules by sympathetic cooling with alkaline-earth atoms in a magnetic trap.