Knowledge Bank

High-resolution infrared spectra of the $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C-methanol\nu 1$ band have been obtained by slit-jet absorption spectroscopy. A total of 1278 lines have been recorded from 3665 to $3708cm-1$ with several ``holes'' resulting from strong water absorption lines. Thirty five subbands of the $\nu 1$ band with $K=0,1,2$ have been assigned based on polynomial fits and ground-state combination differences. Half of the upper states are split by perturbations with matrix elements in the range of $1-3cm-1$. The deperturbed data show an approximately regular pattern of torsional energies with a torsional tunnelling splitting of $7cm-1$ at $K=0$.