Fourier transform microwave spectroscopy of ScS (X2Σ+) and YS (X2Σ+)

► Measured rotational spectra of YS and ScS (X2Σ+) with FTMW/laser ablation methods. ► Accurate bond length obtained for ScS and YS for examination of periodic trends. ► Hyperfine constants suggest Sc-S and Y-S bonds more covalent than O analogs.