Dipole moment of ArH+X1Σ+ from analysis of pure rotational and vibration-rotational spectra

By a direct fit to 431 experimental wave numbers of pure rotational and vibration-rotational transitions of ArH+X1Σ+ in six isotopic variants, 16 coefficients of radial functions defining the Born–Oppenheimer potential energy, adiabatic and nonadiabatic effects have been determined at σ̂=0.885 and F=4.07×1015. Using a relation between nonadiabatic rotational effects and electric and magnetic properties of the molecule, a permanent dipole moment of 40Ar1H+ is estimated as μ0=2.12(55) D which agrees both with the ab initio value 2.2(1) D and the experimental result μ0=3.0(6) D within quoted error limits.