Born-Oppenheimer breakdown effects and hyperfine structure in the rotational spectrum of strontium monosulfide, SrS

A newly constructed Fourier transform microwave spectrometer has been used to record the pure rotational spectra of four isotopomers of SrS (⁸⁸Sr³²S, ⁸⁷Sr³²S, ⁸⁶Sr³²S, and ⁸⁸Sr³⁴S) between 6 and 26 GHz. The molecules were produced by reacting laser ablated strontium with carbonyl sulfide (0.1% in argon). Pure rotational transitions in the ground, first and second vibrational states have been observed. The data set has enabled a multi-isotopomer fit. Born-Oppenheimer breakdown terms for both atoms have been determined. The ⁸⁷Sr nuclear quadrupole coupling constant in ⁸⁷Sr³²S has been determined for the first time.