Microwavea-Dipole Transitions of CH2DOH and CHD2OH in Excited Torsional States

Abstract Previously identified, measured, and rotationally assigned but unpublished J = 0–1 and 1–2 microwave a -dipole lines for excited states of the torsion for CH 2 DOH and CHD 2 OH are given torsional assignments for the first four excited states. The troublesome assignments were for the K −1 = 0 lines of the o 2 state of CH 2 DOH and the e 2 state of CHD 2 OH, where a resonance is found for the J 0 J levels. The assignment for these states was facilitated by combination differences with the b - or c -dipole intratorsional state transitions, relative intensities, and FIR combination differences for the e 2 and e 3 states of CH 2 DOH. A few new b - and c -dipole assignments are reported for o 2 of CH 2 DOH and e 2 of CHD 2 OH. Transitions for these two states have been analyzed to estimate the strength of the resonant interaction and energy difference for the levels involved and to estimate how well the theory is predicting the K −1 -dependent torsional energy levels. The empirically determined Δ B and Δ C from nonrigidity for each species for the four excited states should prove helpful for future calculations of vibration–internal rotation–overall rotation interactions in these molecules.