CO2 laser saturation Stark spectra and global rovibrational analysis of the main isotopic species of carbonyl sulfide (OC34S,O13CS,and 18OCS)

Stark spectra of OC³⁴S, O¹³CS, and ¹⁸OCS have been recorded with an intracavity CO₂ laser spectrometer. The observed transitions are the 2ν₂ band and the associated hot bands from ν₂¹, ν₁, 2ν₂⁰, 2ν₂², ν₁ + ν₂¹, 3ν₂¹, and 3ν₂³. One line has also been observed in the 00⁰1 ← 02⁰0 band of OC³⁴S. For each isotopic species of OCS, a global weighted least-squares analysis has been applied simultaneously on all available zero-field and Stark data, yielding coherent sets of rovibrational and electrical molecular parameters. From the equilibrium rotational constants we have deduced an improved equilibrium structure for the OCS molecule.