Collisional effects in the formation of cold guided beams of polar molecules

TL;DR

This paper investigates how collisional effects influence the formation of cold guided beams of polar molecules, revealing how source parameters affect beam properties and providing a model that explains velocity-dependent losses near the nozzle.

Contribution

It introduces a model accounting for velocity-dependent collisional losses that explains the parameter dependence of guided molecular beams.

Findings

Velocity distribution changes with source parameters.

Guided signal depends on trapping electric field.

Model accurately reproduces collisional effects.

Abstract

High fluxes of cold polar molecules are efficiently produced by electric guiding and velocity filtering. Here, we investigate different aspects of the beam formation. Variations of the source parameters such as density and temperature result in characteristic changes in the guided beam. These are observed in the velocity distribution of the guided molecules as well as in the dependence of the signal of guided molecules on the trapping electric field. A model taking into account velocity-dependent collisional losses of cold molecules in the region close to the nozzle accurately reproduces this behavior. This clarifies an open question on the parameter dependence of the detected signal and gives a more detailed understanding of the velocity filtering and guiding process.