ROTATIONAL SPECTRA AND STRUCTURES OF THE H2S-H2O AND $(H_{2}S)_{2}$ COMPLEXES

A pulsed-beam Fabry-Perot cavity microwave spectrometer has been employed in the measurement of rotational spectra of $H_{2}S-H_{2}$O and $(H_{2}S)_{2}$. The a-type $K=0$ rotational transitions of both species have been observed in the 6-21 GHz range. The spectrum of H2S-H2O is expected to be analogous to that of $H_{2}^{18}O-H_{2}O$ and $^{15}N_{2}-H_{2}O$ (described in the previous papers) for which two tunneling motions,1 give rise to four components for each transition. For $H_{2}S-H_{2}O$ and its $^{34}S$ and $^{18}O$ isotopic forms, 3 of the 4 components have been resolved. The molecular parameters for $H_{2}S-H_{2}O$ are: [FIGURE] The energy levels of $H_{2}S$ dimer and its isotopic forms are expected to be similar to those of water $dimer.^{1}$ While hoping to observe a wider range of states than presently known for water dimer, at present only the $K = 0$ states for the E levels for $(H_{2}S)_{2}, (H_{2}^{34}S)$ and $(D_{2}S)_{2}$, and the similar levels of the mixed isotopic forms have been observed. For $(H_{2}S)_{2}$ the rotational constants are: $B (E^{+}) 1749.310(1) MHz$ and $B (E***) = 1748.109(1)$. The structures of both complexes will be presented based on 9 isotopic species of $H_{2}S-H_{2}O$ and 7 species of $(H_{2}S)_{2}$. Comparisons of the hyperfine structure, dipole moments and structural implications will be presented.