Electrostatic extraction of cold molecules from a cryogenic reservoir

TL;DR

This paper introduces a method to produce a continuous, high-density beam of slow, cold polar molecules using cryogenic cooling and electrostatic guiding, enabling advanced molecular experiments.

Contribution

The authors demonstrate a novel combination of cryogenic buffer gas cooling and electrostatic extraction to generate dense, slow molecular beams with high internal state purity.

Findings

Achieved fluxes up to 7×10^{10} molecules/sec for ND3

Produced single-state populations up to 82% for H2CO

Generated high-density, internally cold molecular beams

Abstract

We present a method which delivers a continuous, high-density beam of slow and internally cold polar molecules. In our source, warm molecules are first cooled by collisions with a cryogenic helium buffer gas. Cold molecules are then extracted by means of an electrostatic quadrupole guide. For ND$_3$ the source produces fluxes up to $(7 \pm ^{7}_{4}) \times 10^{10}$ molecules/s with peak densities up to $(1.0 \pm ^{1.0}_{0.6}) \times 10^9$ molecules/cm$^3$. For H$_2$CO the population of rovibrational states is monitored by depletion spectroscopy, resulting in single-state populations up to $(82 \pm 10)%$.