VIBRATION-ROTATION INTERACTION IN QUASI-LINEAR MOLECULES.

Author Institution: National Bureau of Standards; National Research CouncilThe unusual dependence of the rotational constant B on the bending vibrational quantum number $v_{2}$ obtained from the microwave spectrum of CsOH and CsOD is discussed with the help of a formalism derived from an exact vibration-rotation Hamiltonian containing a curvilinear bending coordinate. Unfortunately, a lack of knowledge concerning the harmonic force field for these two molecular species prevents any reliable quatitative conclusions concerning anharmonic constants being drawn from the experimental data. The most that can be said qualitatively appears to be that the observed unusual behavior of $B(v_{2})$ is not necessarily inconsistent with a linear equilibrium structure for the molecules