Collisional properties of cold spin-polarized nitrogen gas: theory, experiment, and prospects as a sympathetic coolant for trapped atoms and molecules

Abstract

We report a combined experimental and theoretical study of collision-induced dipolar relaxation in a cold spin-polarized gas of atomic nitrogen (N). We use buffer gas cooling to create trapped samples of 14N and 15N atoms with densities 5+/-2 x 10^{12} cm-3 and measure their magnetic relaxation rates at milli-Kelvin temperatures. Rigorous quantum scattering calculations based on accurate ab initio interaction potentials for the 7Sigma_u electronic state of N2 demonstrate that dipolar relaxation in N + N collisions occurs at a slow rate of ~10^{-13} cm3/s over a wide range of temperatures (1 mK to 1 K) and magnetic fields (10 mT to 2 T). The calculated dipolar relaxation rates are insensitive to small variations of the interaction potential and to the magnitude of the spin-exchange interaction, enabling the accurate calibration of the measured N atom density. We find consistency between the calculated and experimentally determined rates. Our results suggest that N atoms are promising candidates for future experiments on sympathetic cooling of molecules.

48 pages, 17 figures, 3 tables

References in corpus (7)

• Controlling electronic spin relaxation of cold molecules with electric fields
• Ultracold Rb-OH collisions and prospects for sympathetic cooling
• Electrostatic extraction of cold molecules from a cryogenic reservoir
• Interactions and dynamics in Li + Li_2 ultracold collisions
• Avoided crossings between bound states of ultracold Cesium dimers
• Magnetic trapping of atomic nitrogen (14^N) and cotrapping of NH (X-triplet-Sigma-)
• Cold guided beams of water isotopologs

Cited by in corpus (2)

• Cold N+NH Collisions in a Magnetic Trap
• Cold collisions of N atoms and NH molecules in magnetic fields