title: Note: A modular and robust continuous supersonic expansion discharge source.
abstract: A direct current discharge has been coupled with a continuous supersonic expansion to provide a source of rotationally cold molecular ions for gas phase spectroscopy. Constructed primarily of machinable ceramic and stainless steel, this source design is modular, customizable, and robust. Its performance has been assessed by recording transitions within the nu(2) fundamental band of H(3) (+) using cavity ringdown spectroscopy to determine the rotational temperature of ions produced in the free-jet expansion. Temperature and column density were recorded as a function of discharge current as the source was operated over a period of 200 h. Observed temperatures ranged between 50-110 K, and the ion column densities between 8x10(10) and 2x10(12) cm(-2).
authors.affiliation: Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Kyle N
authors.initials: KN
authors.lastname: Crabtree
authors.forename: Carrie A
authors.initials: CA
authors.lastname: Kauffman
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: McCall