15min:

A. JANCZYK AND L. M. ZIURYS, Department of Chemistry, Department of Astronomy, and Steward Observatory, University of Arizona, Tucson, AZ 85721.

The pure rotational spectra of LiSH (X¹A') and two of its isotopomers (⁶LiSH, LiSD) were recorded using millimeter/submillimeter-wave direct absorption techniques. The molecule was produced by reacting lithium vapor with H₂S in the presence of a d.c. discharge. Transition ranging from J = 1 2 to J = 13 14, spanning the region of 73-520 GHz, were measured for ⁷LiSH, as well as 3-4 transitions for the ⁶Li and deuterium isotopomers. The spectra showed an extensive K_a ladder structure for the three species, which is consistent with the molecule being an asymmetric top. Rotational constants for all three molecules have been determined, as well as r₀ and r_m^(1) structures for LiSH. This study shows that this molecule is bent, with = 93^\circ and therefore is significantly different from the quasilinear LiOH. This structural change likely results from more covalent bonding in LiSH.