Cold and Slow Molecular Beam

TL;DR

This paper demonstrates a hybrid cryogenic buffer gas cell technique to produce cold, slow, and high-flux calcium monohydride molecular beams with near effusive velocity distributions, suitable for precision experiments.

Contribution

It introduces a novel two-stage cryogenic buffer gas cell with a slowing cell to generate cold, slow, and high-flux molecular beams, advancing control over molecular beam velocities.

Findings

Produced CaH beams with velocities of 65 m/s and 40 m/s.

Achieved a longitudinal temperature of 3.6 K in the slowest beam.

Generated fluxes of 10^9 and 5x10^8 molecules per pulse, respectively.

Abstract

Employing a two-stage cryogenic buffer gas cell, we produce a cold, hydrodynamically extracted beam of calcium monohydride molecules with a near effusive velocity distribution. Beam dynamics, thermalization and slowing are studied using laser spectroscopy. The key to this hybrid, effusive-like beam source is a "slowing cell" placed immediately after a hydrodynamic, cryogenic source [Patterson et al., J. Chem. Phys., 2007, 126, 154307]. The resulting CaH beams are created in two regimes. One modestly boosted beam has a forward velocity of vf = 65 m/s, a narrow velocity spread, and a flux of 10^9 molecules per pulse. The other has the slowest forward velocity of vf = 40 m/s, a longitudinal temperature of 3.6 K, and a flux of 5x10^8 molecules per pulse.