Cross Sections and Interpretation of Dissociative Attachment Reactions Producing OH−, O−, and H− in H2O

Dissociative-electron-attachment cross sections for the production of OH−, O−, and H− from water vapor have been determined. These cross sections are discussed within the framework of resonance scattering theory. The relatively low cross sections for the production of OH−, 1.2, 0.85, and 0.85× 10−21 cm2 molecule−1 for maxima of 6.4, 8.4, and 11.2 eV, suggest that the atoms in the H2O− complex are loosely bound together and behave as essentially independent entities. All of the negative ions from H2O appear to be produced from three different electronic states of the molecule. Results from this study are used to draw a hypothetical potential energy diagram for H2O.