Resonance enhancement of electron-projectile excitation in collisions of O5+ ions with H2 targets

The electron-impact excitation cross section for the 1s2 2s(2S)→1s2s2p(4P) transition in O5 has been calculated using the R-matrix method. Resonance contributions are found to increase the background cross section by factors of 2--5 in the 550--700-eV energy region when convoluted with a 1-eV full-width-at-half-maximum Gaussian profile. When convoluted with the Compton profile for H2, however, the difference between the background and resonance enhanced cross sections is less than 5% near the peak. Thus, experiments involving collisions of O5+ ions with H2 targets shed little light on the resonance scattering dynamics found in the near-threshold energy region