Positive and negative ion reactions in carbon dioxide

Abstract

The positive and negative ions produced in carbon dioxide over a wide range of E/N have been examined in a drift tube/mass spectrometer experiment. The positive ion spectra show that unless considerable care is taken to maintain high purity of the gas samples, the dominant ion species are H+(H2O)n and to a lesser extent HCO2+. The spectra are interpreted on the basis of the formation of H2CO3 through chemisorption of CO2 at surfaces in the gas inlet line. For pure CO2 the dominant ions were O2+ and CO2+. The charge exchange reaction O2++CO2 to CO2++O2 was observed at E/N>or approximately=135 Td and values of its reaction rate are reported for 135<E/N<390 Td.