title: A pair of concentric capillaries as an interface for gas chromatography and supersonic jet/multiphoton ionization/mass spectrometry.
abstract: A pair of concentric capillaries was developed to mix helium, which was used as the carrier gas for gas chromatography, with argon for efficient molecular cooling by supersonic jet expansion. A simple instrument was constructed for the evaluation of nozzle diameter using the Hagen-Poiseuille equation. The effects of nozzle diameter, type of expansion gas, flow rate, and the distance from the nozzle to the observation region were investigated. Mixing argon gas with the carrier gas helium resulted in efficient molecular cooling from 30 to 10 K and the complete disappearance of the background signal from the multiphoton ionization spectrum. Consequently, the spectral selectivity was significantly improved and the nozzle was successfully applied to isomer-selective analysis of dichlorotoluenes. Since the dead volume in the nozzle was negligible, it was suitable as an interface for gas chromatography and supersonic jet/multiphoton ionization/mass spectrometry.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan. h-okudaira@cstf.kyushu-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Okudaira
authors.forename: T
authors.initials: T
authors.lastname: Uchimura
authors.forename: T
authors.initials: T
authors.lastname: Imasaka