The high-lying rotational energy levels of the OH radical in the ν = 0 level of the X 2Π state

Abstract

Lambda-doubling and rotational transition frequencies for the OH radical in the ν = 0 level of its X 2Π state have been fitted close to the limit imposed by experimental error for a very wide range of J values. High power centrifugal distortion correction terms (up to N 12) were required in the effective Hamiltonian to achieve this. The traditional power series expansion of the rotational Hamiltonian is only very slowly convergent for the highest N values included (up to N = 47). Nevertheless, reliable interpolation of rotational transition frequencies for intermediate N values is possible from the results, giving values which are superior to those measured directly in the solar spectrum. A refined and extended table of rotational term values for OH in its ground state has been computed from the molecular parameters.