The pure rotational spectrum of ZnS (X1Σ+)

The pure rotational spectrum of ZnS (X-1 Sigma(+)) has been measured using direct-absorption millimeter/submillimeter techniques in the frequency range 372-471 GHz. This study is the first spectroscopic investigation of this molecule. Spectra originating in four zinc isotopologues ((ZnS)-Zn-64, (ZnS)-Zn-66. (ZnS)-Zn-68, and (ZnS)-Zn-67) were recorded in natural abundance in the ground vibrational state, and data from the nu=1 state were also measured for the two most abundant zinc species. Spectroscopic constants have been subsequently determined, and equilibrium parameters have been estimated. The equilibrium bond length was calculated to be r(e) similar to 2.0464 angstrom, which agrees well with theoretical predictions. In contrast, the dissociation energy of D-E similar to 3.12 eV calculated for ZnS, assuming a Morse potential, was significantly higher than past experimental and theoretical estimates, suggesting diabatic interaction with other potentials that lower the effective dissociation energy. Although ZnS is isovalent with ZnO, there appear to be subtle differences in bonding between the two species, as suggested by their respective force constants and bond length trends in the 3d series. (C) 2009 Elsevier Inc. All rights reserved.