Observation and analysis of high-J o1−e1 inter-state transitions in CH2DOH

We report the observation and assignments of several series of transitions in ${\mathrm{CH}}_2\mathrm{DOH},$ including a new and intense series of Q-branch c-type transitions between the $e_1$ and $o_1$ torsional substates through high values of the rotational quantum number J. Other transitions assigned are c-type R-branch and P-branch transitions between these two substates and a-type lines within the $e_1$ and $o_1$ substates. The assignments were facilitated by initial analysis of the strong Q-branch series, as recorded by the fast scan submillimeter spectroscopy technique (FASSST). The assigned lines of ${\mathrm{CH}}_2\mathrm{DOH}$ include the first inter-state transitions in the sub-millimeter-wave region and the first to possess high J-values. The completeness of the data generated by FASSST and the success of a simple power series analysis suggest that many parts of the spectrum of ${\mathrm{CH}}_2\mathrm{DOH}$ may be far more tractable than previously believed. The data should be useful in the development of a full Hamiltonian and in the assignment of astronomical emission features.