Absolute cross sections for dissociative electron attachment to H₂O and D₂O

Abstract

The dissociative electron attachment (DEA) process to water (H2O) and heavy water (D2O) has been studied in the gas phase in a cross beam experiment for electron energies up to 20 eV. The apparatus used eliminates discrimination due to the kinetic energy and angular distribution of the ions. The cross sections are normalized to absolute values using the cross section for production of O− from O2 (Rapp and Briglia 1965 J. Chem. Phys. 43 1480). These are the first exhaustive measurements of absolute cross sections for both the H− and O− from H2O and D− and O− from D2O at all the three resonances. The results are compared with the scarce data available in the literature. Isotope effect is observed at the 12 eV resonance in the H− channel and at all the three resonances in the O− channel.