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Updated: Jun 15, 2026

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
Communications: Development and characterization of a source of rotationally cold, enriched para-H3+
Brian A Tom1, Andrew A Mills, Michael B Wiczer
1Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. brian.tom@usafa.edu
Abstract:
In an effort to develop a source of H(3)(+) that is almost entirely in a single quantum state (J=K=1), we have successfully generated a plasma that is enriched to approximately 83% in para-H(3)(+) at a rotational temperature of 80 K. This enrichment is a result of the nuclear spin selection rules at work in hydrogenic plasmas, which dictate that only para-H(3)(+) will form from para-H(2), and that para-H(3)(+) can be converted to ortho-H(3)(+) by subsequent reaction with H(2). This is the first experimental study in which the H(2) and H(3) (+) nuclear spin selection rules have been observed at cold temperatures. The ions were produced from a pulsed solenoid valve source, cooled by supersonic expansion, and interrogated via continuous-wave cavity ringdown spectroscopy.
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