Improved molecular constants and empirical corrections for the torsional ground state of the CO stretch fundamental of CH 3OH
The CO stretch fundamental of CH 3OH is analyzed on the basis of previously published diode laser spectra and data from optically pumped far-infrared laser emission. Improved values for Ib, Ic, and V3 are presented, and Ia1 and Ia2 are determined separately. Energy levels are calculated, and empirical corrections tabulated, which show that the levels are heavily perturbed around K = 5. By including these corrections, as well as cubic effects in J( J + 1), infrared transition energies can be evaluated for K ≤ 10 and J ≤ 24 with an accuracy approaching the Doppler limit. The improved model is used for performing additional far-infrared laser line assignments.