A Bright, Slow Cryogenic Molecular Beam Source for Free Radicals

TL;DR

This paper introduces a cryogenic buffer gas-cooled molecular beam source that produces bright, slow, and cold beams of free radicals like SrF, with detailed characterization and potential advantages over existing methods.

Contribution

The paper presents a new cryogenic buffer gas source capable of generating bright, slow, and cold beams of free radicals, with detailed characterization and construction guidance.

Findings

Beam brightness of 1.2 x 10^11 molecules/sr/pulse in ground state

Forward velocity around 140 m/s

Rotational temperature approximately 1 K

Abstract

We demonstrate and characterize a cryogenic buffer gas-cooled molecular beam source capable of producing bright beams of free radicals and refractory species. Details of the beam properties (brightness, forward velocity distribution, transverse velocity spread, rotational and vibrational temperatures) are measured under varying conditions for the molecular species SrF. Under typical conditions we produce a beam of brightness 1.2 x 10^11 molecules/sr/pulse in the rovibrational ground state, with 140 m/s forward velocity and a rotational temperature of approximately 1 K. This source compares favorably to other methods for producing beams of free radicals and refractory species for many types of experiments. We provide details of construction that may be helpful for others attempting to use this method.