Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms - a new hope

TL;DR

This paper investigates the interaction potentials between NH molecules and various atoms, identifying Be and Mg as promising candidates for sympathetic cooling to ultracold temperatures due to their weaker anisotropic interactions.

Contribution

The study provides detailed ab-initio potential energy surfaces for NH with alkali-metal and alkaline-earth atoms, highlighting the suitability of Be and Mg for ultracold molecule cooling.

Findings

Deep covalent wells with alkali-metal atoms lead to strong inelastic collisions.

Shallower wells with Be and Mg suggest weaker inelastic collisions.

Be and Mg are promising for sympathetic cooling of NH.

Abstract

We explore the potential energy surfaces for NH molecules interacting with alkali-metal and alkaline-earth atoms using highly correlated ab-initio electronic structure calculations. The surfaces for interaction with alkali-metal atoms have deep wells dominated by covalent forces. The resulting strong anisotropies will produce strongly inelastic collisions. The surfaces for interaction with alkaline-earth atoms have shallower wells that are dominated by induction and dispersion forces. For Be and Mg the anisotropy is small compared to the rotational constant of NH, so that collisions will be relatively weakly inelastic. Be and Mg are thus promising coolants for sympathetic cooling of NH to the ultracold regime.