# INFRARED ABSORPTION SPECTROSCOPY OF MOLECULAR IONS IN A CORONA-EXCITED SLIT-JET EXPANSION

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 Title: INFRARED ABSORPTION SPECTROSCOPY OF MOLECULAR IONS IN A CORONA-EXCITED SLIT-JET EXPANSION Creators: Amano, T.; Xu, Yunjie; Fukushima, Masaru; McKellar, A. R. W. Issue Date: 1995 Publisher: Ohio State University Abstract: A corona-excited slit nozzle has been constructed as part of our contiuing $effort^{1}$ to investigate jet-cooled ion sources for infrared absorption spectroscopy. Spectra of four protonated ions, $H_{3}^{+}, HN_{2}^{+}, H_{3}O^{+}$, and $ArH^{+}$ generated in a continuous slit-jet expansion have been studied using an IR difference frequency laser source in the $2400-3500 cm^{-1}$ region. The new corona-excited jet gives a significant improvement (up to 50 times better) in signal-to-noise ratio compared to our previously $reported^{1}$ "hollow cathode" jet discharge source. Furthermore, the observed effective rotational temperatures were lower than with the hollow cathode source: about 30 K for ${HN_{2}}^{+}$, and 70 K for the other three ions, which are more difficult to cool because of their larger rotational level spacings. The rotational populations of some of the ions show strong non-Boltzmann characteristics for higher levels. This and other experimental observations will be discussed in terms of the dynamics of the discharge jet expansion. Description: 1. M. Fukushima, M. -C. Chan, Y. Xu, A. Taleb-Bendiab, and T. Amano, Chem. Phys. Lett. 230, 561 (1994). Author Institution: Ibaraki University, 2-1-1 Bunkyo, Mito 310, Japan.; Mitsubishi Heavy Industries Ltd., 8-1, Sachiura 1, Kanazawa, Yokohama 236, Japan.; National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada. URI: http://hdl.handle.net/1811/29686 Other Identifiers: 1995-RJ-02