Knowledge Bank

Recently, preliminary investigations on the microwave and millimeterwave spectra of methyl hydroperoxide $(CH3OOH)$ have been reported (1). The two lowest CH-torsional states $O+$ and $O-$ are coupled by strong Coriolis interactions. ``Forbidden” transitions ($O+\to O-$ with $\Delta KC=1$) have been observed when asymmetry splitting and $CH3$-rotational splitting are comparable in magnitude. In the present contribution an accurate Hamiltonian is presented, which describes the $O+$ and $O-$ states. A 22-term Hamiltonian was adjusted to 160 experimental data; the average difference between observed and calculated transition frequencies was 140 kHz. The energy difference between the rotational ground state levels of $O+$ and $O-$ was determined to be 448760.3(1) MHz. $CH3$- rotational splittings have been analysed and were treated using perturbation theory.