Updated Excitation and Ionization Cross Sections for Electron Impact on Atomic Oxygen

Cross sections for the excitation and ionization of atomic oxygen by electron impact are presented as the result of a critical review of experimental and theoretical work on this subject. An effort has been made to compile the most accurate and complete set of cross sections available. More than 60 profiles of excitation cross section versus electron-impact energy are presented. These include transitions to the forbidden metastable O(2p4 1D) and O(2p4 1S) states, the allowed autoionizing O(2p5 3P o) state, nine allowed Rydberg series, and twenty-nine forbidden Rydberg series. Recommended ionization cross sections for transitions to the outer-electron ionization states O+(4S o), O+(2Do), O+(2Po), to the inner-electron ionization state O+(4P), and to the O2+ state are also given. Many of these excitation and ionization cross sections are based on recently published laboratory measurements, and differ from previously accepted values by factors of ∼2–3, and in a few cases by up to a factor of 10. The data presented in this report will be useful in calculations of aeronomical and artificially-induced electron impact on atomic oxygen, an important component of the upper atmosphere.