THE MILLIMETER-WAVE ROTATIONAL SPECTRUM OF TRICHLOROACETONITRILE - A STUDY OF H3 SPLITTING IN A NEAR-SPHERICAL MOLECULE

The ground state rotational spectrum of trichloroacetonitrile. CI3CCN, was measured up to 376 GHz and J = 112. A splitting of the K = 3 transitions was observed at high J and allowed the determination of the sextic "splitting" constant h3, in addition to the usual symmetric top spectroscopic constants. It was found that the near-spherical nature of Cl3CCN causes the h3 term to have a perceptible effect also on other low-K transitions. This was accounted for by diagonalization of Watson′s fully reduced symmetric top Hamiltonian and, in the process, it became possible to determine also the rotational constant A from the measured ΔJ = 1, ΔK = 0 transitions. © 1993 Academic Press, Inc.