title: A cold and slow molecular beam.
abstract: Employing a two-stage cryogenic buffer gas cell, we produce a cold, hydrodynamically extracted beam of calcium monohydride molecules with a near effusive velocity distribution. Beam dynamics, thermalization and slowing are studied using laser spectroscopy. The key to this hybrid, effusive-like beam source is a "slowing cell" placed immediately after a hydrodynamic, cryogenic source [Patterson et al., J. Chem. Phys., 2007, 126, 154307]. The resulting CaH beams are created in two regimes. In one regime, a modestly boosted beam has a forward velocity of v(f) = 65 m s(-1), a narrow velocity spread, and a flux of 10(9) molecules per pulse. In the other regime, our slowest beam has a forward velocity of v(f) = 40 m s(-1), a longitudinal temperature of 3.6 K, and a flux of 5 × 10(8) molecules per pulse.
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. lu@cua.harvard.edu
authors.forename: Hsin-I
authors.initials: HI
authors.lastname: Lu
authors.forename: Julia
authors.initials: J
authors.lastname: Rasmussen
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Wright
authors.forename: Dave
authors.initials: D
authors.lastname: Patterson
authors.forename: John M
authors.initials: JM
authors.lastname: Doyle