Dipole moment of ArH +X 1Σ+ from analysis of pure rotational and vibration-rotational spectra

Abstract

By a direct fit to 431 experimental wave numbers of pure rotational and vibration-rotational transitions of ArH +X 1 Σ + in six isotopic variants, 16 coefficients of radial functions defining the Born–Oppenheimer potential energy, adiabatic and nonadiabatic effects have been determined at σ ̂ =0.885 and F=4.07×10 15. Using a relation between nonadiabatic rotational effects and electric and magnetic properties of the molecule, a permanent dipole moment of 40 Ar 1 H + is estimated as μ 0=2.12(55) D which agrees both with the ab initio value 2.2(1) D and the experimental result μ 0=3.0(6) D within quoted error limits.