Collisionally induced hyperfine-structure transitions of OH

Abstract

The theory of excitation of the internal structures of OH by electron or heavy-particle impact is formulated within the quantum-mechanical close-coupling approximation, incorporating spin-orbit and hyperfine interactions. In the case of electron impact, explicit Born formulae are derived and the selection rules are discussed for the dipole- and the quadrupole-induced transitions. Numerical results are reported for the electron excitation cross sections of the hyperfine-structure transitions among the lower-lying rotational ladders of two states.