Electron-triggered processes in halogenated carboxylates: dissociation pathways in CF₃COCl and its clusters

Area of Science:

• Atmospheric Chemistry
• Physical Chemistry
• Chemical Physics

Background:

• Trifluoroacetyl chloride (CF3COCl) is an atmospheric degradation product of hydrochlorofluorocarbons.
• It is a potential source of reactive halogen radicals.
• Its electron reactivity was previously uninvestigated.

Purpose of the Study:

• To investigate the electron ionization and attachment of isolated CF3COCl molecules and their clusters.
• To understand the fragmentation pathways and ion formation.
• To explore potential atmospheric implications.

Main Methods:

• Molecular beam experiment.
• Electron ionization and attachment studies.
• Quantum chemical calculations.

Main Results:

• Electron ionization at 70 eV causes C-C and C-Cl bond fragmentation, yielding CF3+, COCl+, and CF3CO+ ions.
• Electron attachment below 3 eV primarily breaks the C-Cl bond, forming Cl- ions.
• Electron attachment above 4 eV breaks the C-C bond, forming CF3- ions.
• Cluster studies show stabilization of intact negative ions and formation of M·Cl2- ions.

Conclusions:

• CF3COCl undergoes significant fragmentation upon electron impact, both in isolated molecules and clusters.
• Electron attachment leads to characteristic bond dissociations and negative ion formation.
• The findings provide insights into the electron-induced chemistry of CF3COCl in atmospheric processes.