MICROWAVE-SPECTRUM OF AR-H2O - DIPOLE-MOMENT, ISOTOPIC STUDIES, AND O-17 QUADRUPOLE COUPLING-CONSTANTS

Microwave spectra for the K = 0 states of ArH2O, ArD2O, ArHOD, ArH218O, and ArH217O were obtained using a pulsed-nozzle Fourier-transform microwave spectrometer. The observed states, which correlate to the 000 and 101 rotational states of free H2O, are labeled Σ(000) and Σ(101), respectively. For the ArH2O species, the results are in excellent agreement with the far-infrared data of Cohen et al. (J. Chem. Phys., 89, 4494-4504 (1988) and 92, 169-177 (1990)). The present data are also compared with predictions from the three anisotropic potentials proposed by Hutson [J. Chem. Phys., 92, 157-168 (1990)] to interpret the far-infrared spectrum of the complex. The μa dipole moment, 17O nuclear quadrupole coupling constants, and Coriolis perturbations, are in good agreement with predictions from one potential, but in poor agreement with predictions from the other two potentials. The dipole moment for the Σ(000) state specifies the coefficient, v10, of cos θAr in the Legendre expansion of the van der Waals angular potential. Here θAr is the angle between the C2 axis of H2O and the line joining the centers of mass of the two bonding partners. We find |v10| = 3.3 cm-1. © 1990.