MILLIMETER-WAVE SPECTRUM OF THE NO DIMER
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Date
1997
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
We are studying the pure rotational spectrum of the NO dimer, $(NO)_{2}$. The dimers am produced using a continuous supersonic jet source, and probed using a mm-wave spectrometer based on harmonic multiplication. Microwave radiation (75-100 GHz) from a Gunn oscillator is multiplied ($\times 3$ or $\times 4$) in commercial tripler, focussed through the jet by Teflon lenses, and detected by a helium-cooled In Sb bolometer. The frequency scan and data collection are under microcomputer control. The computer also turns the jet off and on at intervals of 5 scans (about 5 sec), and automatically subtracts the background and sample spectra. Previously 4 rotational transitions of $(NO)_{2}$= in the O to 23 GHz microwave region had been $reported.^{h}$ Currently, we have measured about 80 new transitions in the frequency range from 227 To 382 GHz. with J values from 5 to 16, and $K_{a}$ values from 2 to 8. The underlying $^{14}N$ hyperfine structure is partially resolved for some of the transitions, The observed line positions are quite well predicted by the existing molecular parameters from our analysis of the $\nu_{1}$ infrared band, $^{i}$ but the new data will obviously allow a considerably more precise set of parameters to be derived. These new mm-wave results do not directly address the two great mysteries of the No dimer, namely the locations of the intermolecular vibrational mode and of he low-lying electronic states. We still hope to address the former mystery by means of long--path, low temperature FT spectroscopy in the far-ir region.
Description
$^{h}$C. M. Western, P.R.R. Langridge-Smith, B.J. Howard, and S.E. Novick, Mol. Phys. 44. 145 (1981); S. Kukolich, J. Mol. Spectrose, 98, 80 (1983). $^{i}$B. J. Howard and A.R.W. McKellar, Mol. Phys. 78, 55 (1993).
Author Institution: Steacie institute for Molecular Sciences, National Research Council of Canada; Department of Physics and Astronomy, Ibaraki University
Author Institution: Steacie institute for Molecular Sciences, National Research Council of Canada; Department of Physics and Astronomy, Ibaraki University