Millimeter- and submillimeter-wave spectra of platinum monosulfide (PtS) in the X3Σ0- state

► The millimeter- and submillimeter-wave spectra of PtS were observed. ► Rotational transitions were recorded for four isotopomers in the X3Σ0- ground state. ► The spectroscopic constants were determined using a Hund's case (c) Hamiltonian. ► The lower limit of 3Σ0--3Σ1- is estimated from a Hund's case (a) analysis.