We consider the prospect of using ultracold hydrogen atoms for sympathetic cooling of fluorine atoms to microkelvin temperatures. We carry out quantum-mechanical calculations on collisions between cold F and H atoms in magnetically trappable states and show that the ratio of elastic to inelastic cross sections remains high across a wide range of temperatures and magnetic fields. For F atoms initially in the spin-stretched state (${}^2{P}_{3/2}$, $f=m_f=+2$), sympathetic cooling appears likely to succeed from starting temperatures around 1 K or even higher. This occurs because inelastic collisions are suppressed by $p$-wave and $d$-wave barriers that are 600 mK and 3.2 K high, respectively. In combination with recent results on $\mathrm{H}+\mathrm{NH}$ and $\mathrm{H}+\mathrm{OH}$ collisions [M. L. González-Martínez and J. M. Hutson, Phys. Rev. Lett. 111, 203004 (2013)], this establishes ultracold H atoms as a very promising and versatile coolant for atoms and molecules that cannot be laser-cooled.

• Received 13 July 2013

DOI:https://doi.org/10.1103/PhysRevA.88.053420