HGH-RESOLUTION NEAR-INFRARED ABSORPTIONS of $CH_{4}$/He PLASMAS
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Date
2003
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Near infrared absorptions $(11000-13000 cm^{-1})$ of a gaseous plasma generated by discharging a gas mixture of He and $CH_{4}$ (at a ratio of 220:1 to give a total pressure of 860 mTorr) was studied using a high-resolution Ti:sapphire laser spectrometer. Using a home-built AC high voltage power supply and a 2 m long multi-traversal hollow cathode discharge cell equilibrated at 210 K, a peak-to-peak discharge current of 1-1.5 A was maintained for the plasma. The absorption signals were detected using phase-sensitive detection with concentration modulation at 5-10 kHz. In addition to the absorptions due to the Phillips band system ($^{1}Pi_{u} - ^{1}Sigma_{g}$ electronic transitions) of $C_{2},^{a}$ several unidentified bands were also observed with good signal-to-noise ratio. Based on the earlier work of Ballik and Ramsey,$^{b}$ and $S. P. Davis et al.,^{c}$ the analysis of the spectrum is underway.
Description
$^{a}$ J. G. Phillips, Ap. J. 107, 389 (1948). $^{b}$ J. G. Phillips, Ap. J. 137, 84 (1963). $^{c}$ S. P. Davis, M. C. Abrams, J. G. Phillips, and M. L. P. Rao, J. Opt. Soc. Am. B5, 2280 (1988).
Author Institution: Department of Chemistry, The Chinese University of Hong Kong
Author Institution: Department of Chemistry, The Chinese University of Hong Kong