15min:

Z.-D. SUN, Department of Physical Sciences, University of New Brunswick, Saint John, NB, Canada E2L 4L5;; R. M. LEES AND L.-H. XU, Department of Physics, Yantai University, 264005, P. R. China.

We have extended the sub-Doppler spectroscopic study of the ₈ C-O stretching fundamental band of methanol with a dual-mode CO₂-laser/microwave-sideband spectrometer\footnoteZ.-D.~Sun, R.M.~Lees, L.-H.~Xu, M.Yu.~Tretyakov, and V.V.~Dorovskikh, Rev.~Sci.~Instrum. 75, 1052 (2004).. A further 492 transitions, including a number of overlapped and doublet lines unresolved in the Doppler-limited spectra of the broadband scanning mode, have been observed as saturation dips with a resolution of 0.4 MHz in the sub-Doppler detection mode and their frequencies have been measured with accuracy of order \pm200 kHz. For K from 1 to 5, energy term values for the excited-state levels of these A- and E-species transitions have been determined using known ground-state energies and have been fitted to Taylor-series expansions in powers of J(J+1) to yield accurate expansion coefficients. The present, together with previous sub-Doppler measurements^a,\footnoteZ.-D.~Sun, F.~Matsushima, S.~Tsunekawa, and K.~Takagi, J.~Opt.~Soc.~Am.~B 17, 2068 (2000)., provide a high accuracy database for CH₃OH, with application to methanol vibrational interaction studies and the interpretation of the optically pumped far-infrared laser emission spectrum.