THE SUBMILLIMETER ROTATION TUNNELING SPECTRUM OF THE WATER DIMER

Rotational tunneling transitions have been measured for the (Ka = 0, lower) → (Ka = 1, upper) and the (Ka = 1, lower) → (Ka = 2, upper) bands of (H2O)2. Although some of these transitions have been reported in an earlier publication, a more detailed discussion of the experiment and of the results is presented here. Transitions have been measured by direct absorption spectroscopy in a continuous slit nozzle expansion using either harmonics from klystrons or sidebands. These data along with previous measurements have been analyzed using an IAM-like treatment. A better determination of the A rotational constant and of the value of the largest tunneling splitting has been achieved. © 1991.