Non-dissociative and dissociative ionization of CO, CO2 and CH4 by positron impact

Cross sections for direct and total non-dissociative ionization of CO, CO2 and CH4 by positron impact have been measured for projectile energies ranging from threshold to 2000 eV. For CO and CO2 direct and total dissociative cross sections for several different fragments have been measured. The non-dissociative cross sections are observed to behave similarly to the single ionization cross sections of the light noble gases. The dissociative cross sections resemble that seen recently for N-2, and can be related to models for double ionization of the light noble gases.