Molecular dynamics of dissociative electron attachment in water

Classical trajectory calculations have been used to model dissociative electron attachment (DEA) processes in water. In previously reported experiments, DEA cross-sections show maxima at three different energies between ca. 6 and 12 eV; these have been ascribed to the formation and dissociative decay of three different resonant (anion) states of symmetry ²B₁, ²A₁ and ²B₂ whose parent states are the à ¹B₁, B~¹A₁ and C~ ¹B₂ states, respectively, of neutral water. The present model calculations show that the essential features of the experimental findings can be reproduced using only two anionic potential surfaces; furthermore, most of the observed product ions follow from initial excitation to one (the lower-lying in symmetric geometries) of these. If the two surfaces are related to resonances of symmetry ²B₁ and ²B₂, then all of the observed features associated with resonant electron scattering from water can be rationalised.