Rotational spectra and hyperfine constants of ZrO and ZrS

Abstract

The pure rotational spectra of ZrO and ZrS have been recorded using cavity Fourier transform microwave spectroscopy in the frequency range 9–26 GHz. The molecules were generated by laser ablation of a solid Zr rod in the presence of 0.05% of O2 or H2S, respectively, in either argon or neon. Rotational spectra of five previously unobserved isotopomers of ZrO in the X 1Σ+ state have been measured. Spectra for all five Zr32S isotopomers and for the Zr90S34 isotopomer in natural abundance have also been measured; this is the first report of pure rotational transitions for ZrS. Transitions in several excited vibrational states were also measured for the most abundant isotopomers of both species. Atomic mass-dependent Born–Oppenheimer breakdown correction terms were determined by fitting the data obtained for each molecule to a Dunham-like expression. Values for the equilibrium bond lengths of the two species were also calculated from the results of these fits. For both the Zr91S32 and Zr91O16 isotopomers, nuclear hyperfine structure due to the zirconium nucleus was observed and values for eQq0(91Zr) and CI(91Zr) have been determined. A rotational transition in the low lying a 3Δ state of ZrS has also been observed.