Excitation of fine structure transitions in O by H2

Cross-sections σ(J → J') have been computed for the excitation of fine structure transitions in O(3Pj) by para-H2 in its rotational ground state (j = 0). The potentials were derived as modified fits to the SCF and dispersion energies of interaction for 0-He. Owing to the larger polarizability of H2, compared with He, the cross-sections for excitation by H2 are larger at low collision energies than for excitation by He. The propensities of the cross-sections are the same for both perturbers, with σ(0 → 1) being much smaller than σ(0 → 2) or σ(1 → 2). (author)