A Mechanical Means of Producing Cold, Slow Beams Ofmolecules: a Counter-revolutionary Concept

In this work, we describe a method by which to createcold, slow beams of molecules using a rotatingsupersonic molecular beam source. The supersonicexpansion cools the internal temperature of themolecules and the rotor velocity largely cancels theflow velocity of the beam, slowing the beam. Centrifugal action enhances the backing pressure ofthe supersonic expansion and significantly cools themolecules and further enhances the beam intensity. Theoretical calculations and design specification arepresented, followed by extensive experimental resultsfor both supersonic and effusive molecular beams. The latter includes beams of pure gases and seededbeams, where the molecule of interest is furtherslowed by inverse seeding in a heavy rare gas. Finally, other molecular cooling and trappingtechniques are described includingexperimentally-realized techniques (buffer gasloading, photoassociation of cold atoms, and timedpulsed electric fields) and several new theoreticalideas (e.g. multi-wavelength lasers, laser scooping,intracavity slowing, bichromatic slowing, andreactive scattering).