ROTATIONAL SPECTRUM OF THE METHANE-OZONE VAN DER WAALS COMPLEX USING FT-MICROWAVE SPECTROSCOPY

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 Title: ROTATIONAL SPECTRUM OF THE METHANE-OZONE VAN DER WAALS COMPLEX USING FT-MICROWAVE SPECTROSCOPY Creators: Hight Walker, A. R.; Suenram, R. D.; Fraser, G. T.; Lovas, F. J.; Steyert, D. W.; Mayer, P. Issue Date: 1995 Publisher: Ohio State University Abstract: The microwave spectrum of $CH_{4}-O_{3}$ has been measured using a pulsed-nozzle Fourier transform microwave spectrometer. Large-amplitude motions of both the ozone and the methane monomers complicate the spectrum. Pure a-type rotational transitions and c-type rotation-inversion transitions are observed with the inversion splitting attributed to the motion of the ozone molecule through a heavy atom planar transition state. The observed statistical weights from the spin zero oxygen nuclei are consistent with this type of transition state. The low frequency tunneling motion is on the order of 30 MHz, which is, as expected, significantly lower than the frequency found in $Ar-O_{3}$ of $460 MHz^{1 \ast}$. Internal rotor states of the methane were observed correlating to the A, E, and F states of the free methane. The A and F states of the complex exhibit rigid-rotor like spectra, except for a small deviations resulting from the ozone tunneling mentioned above. The spectrum for the E internal rotor state is complicated by the unquenched angular momentum of the methane and is presently being analyzed. Description: $^{1}$ Meunter, J. S., DeLeon, R. L., Yokozeki, A; Faraday Discuss, Chem. Soc., 1982, 73, 63-70 ${\ast}$ This frequency was obtained via new measured made on the $ArO_{3}$ complex at NIST Author Institution: National Institute of Standards and Technology, Gaithersburg, MD 20899; Wabash College, Crawfordsville, IN 47933; Princeton University, Princeton, NJ 08540 URI: http://hdl.handle.net/1811/29673 Other Identifiers: 1995-RI-03