Dynamics of Low-Energy Electron Attachment to Formic Acid

Abstract

Low-energy electrons (<2 eV) can fragment gas phase formic acid (HCOOH) molecules through resonant dissociative attachment processes. Recent experiments have shown that the principal reaction products of such collisions are formate ions (HCOO-) and hydrogen atoms. Using first-principles electron scattering calculations, we have identified the responsible negative ion state as a transient pi* anion. Symmetry considerations dictate that the associated dissociation dynamics are intrinsically polyatomic: a second anion surface, connected to the first by a conical intersection, is involved in the dynamics and the transient anion must necessarily deform to nonplanar geometries before it can dissociate to the observed stable products.