Photoionization of CO₂ -CO-O₂ Mixtures. Formation and Reactions of Ion Clusters

Various mixtures containing combinations of CO₂, O₂, or CO have been photoionized at 16.7 and 21.2 eV at pressures up to 1.5 torr in the NBS high pressure photoionization mass spectrometer. In CO₂-CO mixtures the interactions of $$ ions eventually lead to the formation of $$ and [(CO)_2-CO₂]⁺ cluster ions, while photoionization of CO₂-CO-O₂ mixtures yields mainly oxygen-containing clusters at higher pressures. The investigation of O₂-CO mixtures also revealed reactions between $$ and CO. The role of impurity reactions involving H₂O is considered in some detail, and the implications of all of these data to the vapor phase radiolysis of CO₂ is discussed.