Dissociative Electron Attachment to Polyatomic Molecules - I : Water

TL;DR

This study investigates dissociative electron attachment in water molecules using velocity map imaging, revealing detailed angular and energy distributions of fragment ions at specific resonant energies, and highlighting complex dissociation dynamics.

Contribution

It provides detailed experimental characterization of DEA in water, including angular distributions and resonance behaviors, advancing understanding of polyatomic molecule dissociation mechanisms.

Findings

Identified resonant states at 6.5 eV, 8.5 eV, and 12 eV in water.

Observed unique angular distributions at 8.5 eV and 11.8 eV resonances.

Revealed dissociation dynamics beyond axial recoil approximation.

Abstract

Using the velocity map imaging technique, we studied and characterized the process of Dissociative Electron Attachment (DEA) in polyatomic molecules like Water, Hydrogen Sulphide, Ammonia, Methane, Formic Acid and Propyl Amine. We present the details of these studies in a series of 5 articles. In the first article here, we discuss the DEA process in gas phase water ($H_{2}O$ and $D_{2}O$) molecules. Electrons of 6.5 eV, 8.5 eV and 12 eV are captured by water molecules in neutral ground state to form $H_{2}O^{-*}$ ($D_{2}O^{-*}$) resonant states which dissociate into an anion fragment and one or more neutrals. Kinetic energy and angular distributions of the fragment anions $H^{-}$($D^{-}$) and $O^{-}$ produced from the three negative ion resonant states in the entire $2\pi$ scattering range are obtained. Unique angular distribution patterns are observed at the 8.5 eV and 11.8 eV resonances showing dissociation dynamics beyond the axial recoil approximation.