Potential energy surfaces for Ar–OH (X 2Π) obtained by fitting to high-resolution spectroscopy

Empirical potential energy surfaces for Ar interacting with OH (X 2Π) are obtained by fitting to experimental results from microwave and stimulated-emission pumping (SEP) spectra of the Ar–OH complex. The sum VΠ and difference V2 of the potentials for A′ and A″ symmetry are determined. The sum potential is 126 cm−1 deep, which is about 24 cm−1 deeper than the ab initio CEPA potential of Degli Esposti and Werner [J. Chem. Phys. 93, 3351 (1990)]. The equilibrium geometry is near-linear, Ar—H–O, with a barrier to internal rotation of 44 cm−1. The potential satisfactorily reproduces all the parameters obtained from the SEP experiments, but not the parity doubling obtained from the microwave spectrum.