title: Molecular beam brightening by shock-wave suppression.
abstract: Supersonic beams are a prevalent source of cold molecules used in the study of chemical reactions, atom interferometry, gas-surface interactions, precision spectroscopy, molecular cooling, and more. The triumph of this method emanates from the high densities produced in relation to other methods; however, beam density remains fundamentally limited by interference with shock waves reflected from collimating surfaces. We show experimentally that this shock interaction can be reduced or even eliminated by cryocooling the interacting surface. An increase of nearly an order of magnitude in beam density was measured at the lowest surface temperature, with no further fundamental limitation reached. Visualization of the shock waves by plasma discharge and reproduction with direct simulation Monte Carlo calculations both indicate that the suppression of the shock structure is partially caused by lowering the momentum flux of reflected particles and significantly enhanced by the adsorption of particles to the surface. We observe that the scaling of beam density with source pressure is recovered, paving the way to order-of-magnitude brighter, cold molecular beams.
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Yair
authors.initials: Y
authors.lastname: Segev
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Natan
authors.initials: N
authors.lastname: Bibelnik
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Nitzan
authors.initials: N
authors.lastname: Akerman
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Yuval
authors.identifier: 0000-0002-6994-4814
authors.initials: Y
authors.lastname: Shagam
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Alon
authors.initials: A
authors.lastname: Luski
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Michael
authors.identifier: 0000-0003-4240-7995
authors.initials: M
authors.lastname: Karpov
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Julia
authors.identifier: 0000-0002-6217-6656
authors.initials: J
authors.lastname: Narevicius
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors.forename: Edvardas
authors.initials: E
authors.lastname: Narevicius
keywords: Molecular beams; atomic beams; molecular cooling; skimmers; supersonic beams