10min:

MASAZUMI ISHIGURO, K. HARADA, K. TANAKA AND T. TANAKA, Devision of Chemistry, Graduate School of Science, Kyushu University, Fukuoka, 812-8581 Japan.

The pure rotational spectrum of the ( p -H₂)- and ( o -H₂)-HCl clusters for both ³⁵Cl and ³⁷Cl species have been recorded by using pulsed supersonic jet technique and millimeter-wave direct absorption spectroscopy in the 67-166 GHz region. These spectra were searched by using prediction based on the result of the infrared spectrum of the Cl-H stretching band.

For ( p -H₂)-HCl, two rotational transitions, J = 3 - 2, 4 - 3, in the ₀ ground state were obseved. For ( o -H₂)-HCl, four rotational transitions split into l -type doubling, J = 2 - 1 5 - 4, in the ₀ ground state were observed. All of spectra were split into hyperfine structure due to Cl nucleus. The intensity of ( p -H₂)-HCl were approximately 1 / 20 that of ( o -H₂)-HCl. The rotatonal constant, B₀, for the ( p -H₂)-H³⁵Cl and ( o -H₂)-H³⁵Cl were determined to be 16627.2089(20) and 16841.5120(54) MHz, respectively. The analysis of hyperfine structure and the search for rovibrational transions of the vdW bending mode are now in progress.