Dissociative Electron Attachment to Molecular Acetonitrile

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Spectroscopy

Background:

• Dissociative electron attachment (DEA) is a fundamental process involving electron interaction with molecules.
• Previous studies on acetonitrile (CH3CN) DEA reported specific fragmentation patterns and resonant states.
• Discrepancies in reported efficiency curves necessitate further investigation into acetonitrile's DEA.

Purpose of the Study:

• To investigate low-energy dissociative electron attachment to molecular acetonitrile (CH3CN).
• To identify and characterize the resonant states of the acetonitrile anion (CH3CN-).
• To elucidate the fragmentation pathways and reaction thresholds for acetonitrile dissociation.

Main Methods:

• Recording efficiency curves for CH2CN-, CHCN-, and CN- product ions.
• Utilizing a high-resolution anion velocity-map imaging spectrometer.
• Obtaining CN- momentum images at specific electron attachment energies (7.10, 7.60, and 8.10 eV).

Main Results:

• Observed efficiency curves differ significantly from previous reports.
• Identified reaction thresholds for e- + CH3CN → H2 + CHCN- at ~1.51 eV and CH3 + CN- at ~1.52 eV.
• Characterized four shape-resonant states (one 2Π and three 2Σ) of CH3CN- involved in fragmentation.
• Interpreted CN- momentum images with four dissociation pathways (two- and three-body).

Conclusions:

• The study provides new insights into the low-energy electron-molecule interactions of acetonitrile.
• The identified resonant states and fragmentation pathways refine our understanding of acetonitrile anion dynamics.
• This research offers a more detailed picture of acetonitrile dissociation mechanisms under electron impact.