  Rovibrational energy level calculations using a high-level intermolecular
potential surface are reported for H2O-CO and D2O-CO. They predict the ground K
= 1 levels to lie about 20 (12) cm-1 above K = 0 for H2O-CO (D2O-CO) in good
agreement with past experiment. But the first excited K = 1 levels are
predicted to lie about 3 cm-1 below their K = 0 counterparts in both cases.
Intensity calculations also indicate that mid-infrared transitions from the K =
0 ground state to this seemingly anomalous excited K = 1 state should be
observable. These predictions are strikingly verified by new spectroscopic
measurements covering the C-O stretch region around 2200 cm-1 for H2O-CO,
D2O-CO, and HOD-CO, and the O-D stretch region around 2700 cm-1 for D2O-CO,
HOD-CO, and DOH-CO. The experiments probe a pulsed supersonic slit jet
expansion using tunable infrared quantum cascade laser or optical parametric
oscillator sources. Discrete perturbations in the O-D stretch region give an
experimental lower limit of about 340 cm-1 for D2O-CO, as compared to our
calculated binding energy of 368 cm-1. Wavefunction plots are presented to help
understand the intermolecular dynamics of H2O-CO. Coriolis interactions are
invoked to explain the seemingly anomalous energies of the first excited K = 1
levels.
