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 ${\text{0.85× 10}}^{\text{−21}}\hspace{0.17em}{\mathrm{cm}}^2\hspace{0.17em}{\mathrm{molecule}}^{\text{−1}}$ 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.