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A cryogenic beam of refractory, chemically reactive molecules with expansion cooling

Hutzler, Nicholas R. and Parsons, Maxwell F. and Gurevich, Yulia V. and Hess, Paul W. and Petrik, Elizabeth and Spaun, Ben and Vutha, Amar C. and DeMille, David and Gabrielse, Gerald and Doyle, John M. (2011) A cryogenic beam of refractory, chemically reactive molecules with expansion cooling. Physical Chemistry Chemical Physics, 13 (42). p. 18976. ISSN 1463-9076. doi:10.1039/C1CP20901A.

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Cryogenically cooled buffer gas beam sources of the molecule thorium monoxide (ThO) are optimized and characterized. Both helium and neon buffer gas sources are shown to produce ThO beams with high flux, low divergence, low forward velocity, and cold internal temperature for a variety of stagnation densities and nozzle diameters. The beam operates with a buffer gas stagnation density of ∼10^(15)–10^(16) cm^(−3) (Reynolds number ∼1–100), resulting in expansion cooling of the internal temperature of the ThO to as low as 2 K. For the neon (helium) based source, this represents cooling by a factor of about 10 (2) from the initial nozzle temperature of about 20 K (4 K). These sources deliver ∼10^(11)ThO molecules in a single quantum state within a 1–3 ms long pulse at 10 Hz repetition rate. Under conditions optimized for a future precision spectroscopy application [A. C. Vutha et al., J. Phys. B: At., Mol. Opt. Phys., 2010, 43, 074007], the neon-based beam has the following characteristics: forward velocity of 170 m s^(−1), internal temperature of 3.4 K, and brightness of 3 × 10^(11) ground state molecules per steradian per pulse. Compared to typical supersonic sources, the relatively low stagnation density of this source and the fact that the cooling mechanism relies only on collisions with an inert buffer gas make it widely applicable to many atomic and molecular species, including those which are chemically reactive, such as ThO.

Item Type:Article
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URLURL TypeDescription Paper
Hutzler, Nicholas R.0000-0002-5203-3635
Hess, Paul W.0000-0003-2985-4221
Additional Information:© 2011 the Owner Societies. Received 24th March 2011, Accepted 27th May 2011, First published on 22nd June 2011. Thanks to Stan Cotreau and Dave Patterson for technical assistance; and John Barry and Edward Shuman for helpful discussions. This work was funded by a NIST Precision Measurement Grant and a grant from the National Science Foundation.
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National Institute of Standards and Technology (NIST)UNSPECIFIED
Issue or Number:42
Record Number:CaltechAUTHORS:20170905-073816674
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Official Citation:A cryogenic beam of refractory, chemically reactive molecules with expansion cooling Hutzler, Nicholas R. Parsons, Maxwell F. Gurevich, Yulia V. Hess, Paul W. Petrik, Elizabeth Spaun, Ben Vutha, Amar C. DeMille, David Gabrielse, Gerald Doyle, John M. Physical Chemistry Chemical Physics v.12, no. 42, 2011
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81116
Deposited By: Ruth Sustaita
Deposited On:05 Sep 2017 17:48
Last Modified:15 Nov 2021 19:41

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