Electron Driven Reactions in Tetrafluoroethane: Positive and Negative Ion Formation

Area of Science:

• Atmospheric Chemistry
• Plasma Science
• Materials Science

Background:

• Chlorine-containing gases like dichlorodifluoromethane (R12) are being phased out due to environmental concerns.
• Tetrafluoroethane (CF3CH2F, R134a) is a leading replacement refrigerant with significantly lower global warming and ozone depletion potentials.
• Electron interactions are fundamental to understanding gas-phase chemistry and atmospheric processes.

Purpose of the Study:

• To investigate the electron-driven fragmentation pathways of tetrafluoroethane (R134a) under electron ionization and attachment.
• To determine the ion efficiency curves for R134a fragmentation from 0 to 25 eV.
• To provide insights into the atmospheric behavior and plasma interactions of R134a.

Main Methods:

• Experimental measurement of ion efficiency curves for positive and negative ion formation.
• Electron ionization and electron attachment techniques.
• Quantum chemical calculations, electron-impact ionization models, and electron-molecule scattering simulations.

Main Results:

• Identified multiple positive ions from R134a dissociation, with CF3+ being the most abundant.
• Determined the first ionization potential of R134a at 13.10 ± 0.17 eV and the second at approximately 14.25 eV.
• Detected C2F3- as the sole anion formed above 8.3 eV.

Conclusions:

• Electron interactions play a significant role in the dissociation of R134a.
• The findings contribute to a better understanding of R134a's atmospheric fate and its application in refrigeration.
• This research supports the development of environmentally friendlier refrigeration technologies and advances plasma science.