Jump to main content
Jump to site search

Volume 67, 1971
Previous Article Next Article

Electron attachment and negative ion-molecule reactions in pure oxygen


The formation of negative ions in oxygen by electron attachment and by subsequent ion-molecule reactions has been studied in the gas phase, using a drift-tube and mass filter. Pressures ranged between 0.65 and 13 mbar (0.5–10 Torr) and reduced fields (field/density) between 3 × 10–18 and 6 × 10–16 V cm2 part.–1. At reduced fields below 10–16 V cm2 part.–1 masses 32 (O2), 64 (O4) and 50 (O2˙H2O) predominate. The O2 formed initially is converted to O4 in a three-body reaction, O2+ 2O2⇌O4+ O2, with a thermal rate constant of 3 ± 0.5 × 10–31 part.–2 ml2 s–1 at 298 K. The back reaction has a rate constant of 7 ± 1 × 10–15 part.–1 ml s–1. The hydrate concentration is related to that of the dimer via the reactions O4+ H2O⇌O2˙ H2O+ O2. The forward rate constant is estimated to be of the order of 10–9 part.–1 ml s–1, and the back measured as 2.5 ± 1 × 10–15 part.–1ml s–1.

At higher fields the initially formed mass 16 (O) is converted irreversibly to mass 48 (O3): O+ 2O2→O3+ O2. The thermal rate constant is measured as 1.05 ± 0.1 × 10–30 part. –2 ml s–1 up to pressures of at least 13 mbar, without any significant change in order. The change in the rate constants with ion collisional energy has also been followed.

Back to tab navigation

Article type: Paper
DOI: 10.1039/TF9716700711
Trans. Faraday Soc., 1971,67, 711-729

  •   Request permissions

    Electron attachment and negative ion-molecule reactions in pure oxygen

    D. A. Parkes, Trans. Faraday Soc., 1971, 67, 711
    DOI: 10.1039/TF9716700711

Search articles by author