15min:
ROTATIONAL SPECTRA OF THE H2-H2O AND H2-D2O CLUSTERS OBSERVED BY MILLIMETER-WAVE SPECTROSCOPY COMBINED WITH A PULSED SUPERSONIC JET TECHNIQUE.

C. J. WHITHAM, KEIICHI TANAKA AND K. HARADA, Department of Chemistry, Kyushu University, Fukuoka, 812-8581, Japan.

Millimeter-wave absorption spectroscopy combined with a pulsed-jet expansion technique was applied to the measurement of the rotational transitions of of the(o)H2-H2O and (o)H2-D2O complexes in the frequency region up to 400 GHz. Rotational transitions of the complexes for two internal rotation states of the water part, Sigma(000) and Pi(101), were observed. The H2 part was, however, limited to the ortho species with nuclear spin of one and internal angular moment of jH2 = 1 and kH2 = 0. No spectral lines for the para-H2 species have been detected.

The Pi(101) state is split into doublet (e and f), due to the Coriolis interaction between the Pi and Sigma sublevels in the (101) state. Analysis of the Coriolis interaction give us the anistropy of potential energy surface around H2O, and the Sigma sublevel is estimated to be located about 10 cm-1 above the Pi sublevel. The center of mass bond length between H2 and water was derived to be 3.598 and 3.610 A, for (o)H2-H2O and (o)H2-D2O, respectively, from the observed rotational constants of the Sigma(000) state. Simple potential fuction was determined by fitting to the observed rotational lines.