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P: Plasmaphysik
P 22: Poster: Magnetische Fusion, Plasmadiagnostik, Dichte Plasmen
P 22.5: Poster
Dienstag, 19. März 2002, 17:40–18:40, HZO Foyer
New Laser Measurement of the Fundamental Band of the CN Radical in a CH4/N2 plasma — •F. Hempel1, J. Röpcke1, A. Pipa1, and P.B. Davies2 — 1Institute of Low Temperature Plasma Physics (INP), Friedrich-Ludwig-Jahn-Straße 19, 17489 Greifswald, Germany — 2Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB21EW, U.K.
The infrared diode laser absorption spectrum of the fundamental band of the CN free radical in its ground electronic state has been measured in a CH4/N2 plasma. Although absolute line strengths of CN are not available its concentration is estimated to be similar to that of C2N2≈1011 cm−3 by comparison with similar plasmas investigated in the past. These CH4-N2-H2-discharges also contained NH3, HCN, CH3, C2H2, C2H4 and C2H6 which were all quantified by IR diode laser absorption spectroscopy. Of these species HCN had the highest concentration and C2N2 the lowest. So far 8 P- and 10 R-branch lines of 12C14N have been measured to an accuracy of 3 · 10−4 cm−1. A fit of these lines to standard formula, fixing the rotational constants to the microwave values, gives a band origin of 2042.42069(21) cm−1. This agrees reasonably well with earlier data from FTIR and optical spectroscopy. Further work is in progress to measure the spectrum of 13C14N.