Sub-doppler infrared spectra of the OH-stretch fundamental of C-13-methanol

High-resolution infrared spectra of the C-13-methanol OH stretching band, n u(1), were obtained by slit-jet absorption spectroscopy at a rotational tem perature of 12-15 K. Twenty-eight subbands were assigned within the range o f upper state quantum numbers, K' = 0 to 2 and J' = 0 to 10. The upper stat e energy levels are heavily perturbed; about half of the assigned subbands were found to be split by perturbations with matrix elements in the range 1 -3 cm(-1). The doubled lines were deperturbed and together with the "unpert urbed" lines were fitted to a global torsion-rotation Hamiltonian with root -mean-square deviation of 0.41 cm(-1) to yield a torsional barrier height o f similar to 405 cm(-1) in the vibrationally excited state. (C) 2000 Academ ic Press.