Three-body breakup in dissociative electron attachment to the water molecule

We report the results of ab initio calculations on dissociative electron attachment to water that demonstrate the importance of including three-body breakup in the dissociation dynamics. While three-body breakup is ubiquitous in the analogous process of dissociative recombination, its importance in low-energy dissociative electron attachment to a polyatomic target has not previously been quantified. Our calculations indicate that three-body breakup is a major component of the observed ${\mathrm{O}}^{-}$ cross section. Our studies suggest that the local complex potential model provides a generally accurate picture of the experimentally observed features in this polyatomic system.

Figure 1

Two- and three-body cross sections calculated for DEA via the ${}^{2}A_1$ state.

Figure 2

Results for DEA via the ${}^{2}B_2$ state, coupled to the ${}^{2}A_1$ state via the conical intersection. (a) Two-body cross sections. (b) Kinetic energy release for DEA leading to ${\mathrm{H}}^{-}+\mathrm{O}\mathrm{H}$. The cross section per unit kinetic energy release is plotted versus incident energy and kinetic energy of ${\mathrm{H}}^{-}+\mathrm{O}\mathrm{H}$ separation. The cut at $12\mathrm{eV}$ is compared with the experimental results of Belic, Landau, and Hall [8] in the inset. (c) Two- and three-body cross sections.

Figure 3

Final results for ${\mathrm{O}}^{-}$ production in DEA to the water molecule, compared with the experimental results of Fedor et al. [10].