Absolute cross sections for anion production by low energy electron impact on physisorbed CO2

Total charge trapping cross sections are reported for CO2 physisorbed onto multilayer Kr substrates. For incident electron energies between 1 and 14 eV, charge trapping proceeds via a dissociative electron attachment (DEA) mechanism, related to that observed in the gas phase. However, near 9.7 eV, coupling between CO2∗− and Kr∗− states results in a significant increase in DEA, and hence charge trapping. Between 1 and 6 eV, we measure absolute total cross sections for anion production with peak values approximately 43 times larger than those for gas phase CO2; this is attributed to effects of the solidʹs polarization energy.