Rotational spectrum and spectroscopic constants of 36Ar⋯H35Cl and 40Ar⋯HCl

The rotational spectrum of the 36Ar⋯H35Cl isotopomer of the Van der Waals dimer between an argon atom and a hydrogen chloride molecule has been observed in natural abundance with a molecular beam, cavity Fourier transform microwave spectrometer. The derived spectroscopic constants are compared with those redetermined for 40Ar⋯H35Cl and 40Ar⋯H37Cl, which have been obtained from new measurements of all rotational transitions below 19 GHz and a new data analysis inclusive of chlorine spin–rotation and hydrogen-chlorine spin–spin effects.