DISSOCIATIVE ELECTRON-ATTACHMENT IN WATER AND METHANOL (5-14 EV)

Energies of D- and O- ions produced by dissociative electron attachment (DA) to D2O and CD3OD (and some partially deuteriated methanols) over three resonance regions (ca. 6.5, 8.5 and 10.5 eV) are reported. In both water and methanol over the first two resonances, the most probable D- ion energy is close to the maximum possible, following rupture of the O-D bond to give ground-state products. Over the same two resonances in water, O- ions appear to be produced in a symmetric dissociation accompanied initially by highly excited D2 and, then, above the appropriate energy threshold, by D atoms. Dissociative pathways for the highest energy resonances are not established, but in methanol, the available experimental evidence points to dissociation from a relatively long-lived, rearranged complex (possibly CD2OD2-). Attention is drawn, where comparison is possible, to similarities between the dissociative behaviour of anions (electron/molecule resonant states) and photodissociation of the parent neutral states.