Fourier transform spectroscopy of the CO-stretching band of O-18 methanol

The high-resolution Fourier transform spectrum of the nu(8) CO-stretching band of CH(3)(18)OH between 900 and 1100 cm(-1) has been recorded at the Canadian Light Source (CLS) synchrotron facility in Saskatoon, and the majority of the torsion-rotation structure has been analyzed. For the nu(t) = 0 torsional ground state. subbands have been identified for K values from 0 to 11 for A and E torsional symmetries up to J values typically well over 30. For nu(t) = 1, A and E subbands have been assigned up to K = 7, and several v, = 2 subbands have also been identified. Upper-state term values determined from the assigned transitions using the Ritz program have been fitted to J(J + 1) power-series expansions to obtain substate Origins and sets of state-specific parameters giving a compact representation of the substate J-dependence. The nu(t) = 0 subband origins have been fitted to effective molecular constants for the excited CO-stretching state and a torsional barrier of 377.49(32) cm(-1) is found, representing a 0.89% increase over the ground-state value. The vibrational energy for the CO-stretch state was found to be 1007.49(7) cm(-1). A number of subband-wide and J-localized perturbations have been seen in the spectrum, arising both from anharmonic and Coriolis interactions, and several of the interacting states have been identified. (C) 2009 Elsevier Inc. All rights reserved.