THE MILLIMETER-WAVE SPECTRUM OF (CH3OH)-O-18 IN THE 119-165 GHZ SPECTRAL RANGE

The rotational millimeter-wave spectrum of (CH3OH)-O-18 has been revis ited, and 162 transitions of both a-and b-types have been measured in the 119-165 GHz spectral range. The spectrum was recorded using the fr equency-modulated millimeter-wave spectrometer at the Justus-Liebig-Un iversitat in Giessen. The (CH3OH)-O-18 transition assignments were bas ed on energy levels obtained from the far-infrared analysis of S. Zhao (Ph.D. thesis, University of New Brunswick, 1993) using the ''Ritz'' program of G. Moruzzi et al. (J. Mel. Spectrosc. 167, 156 (1994)) for direct energy level fitting. The relatively low residuals between calc ulated and observed frequencies highlight the good quality of the resu lts from this program. The newly measured transitions combined with th ose existent in the literature have been included in least-squares fit s to improve the set of rotational, torsional and centrifugal distorti on constants for O-18 methanol.