Dynamics of the dissociative electron attachment in H2O and D2O: The A1 resonance and axial recoil approximation#

Abstract

The dynamics of the formation and decay of negative ion resonance of A1 symmetry at 8.5 eV electron energy in the dissociative electron attachment (DEA) process in H2O and D2O are investigated using the velocity slice imaging technique. While the highest energy hydride ions formed by DEA show angular distributions characteristic to the A1 symmetry, those formed with low-kinetic energy show considerably different angular distributions indicating changes in the orientation of the dissociating bond due to bending mode vibrations. Our observations are quite different from the recently reported measurements, but consistent with the fully quantum calculations. Dynamics of the 2A1 negative ion resonance in water is probed using velocity slice imaging of H– from H2O and D– from D2O. While the momentum distributions of the highest energy ions agree with quantum calculations, those of low energy ions indicate the role of bending mode excitations before dissociation.