Anionic Reactions Degrading SF₆ Using Metals: Insights From the Gas Phase

Area of Science:

• Inorganic Chemistry
• Physical Chemistry
• Mass Spectrometry

Background:

• Alkali metals are known to degrade sulfur hexafluoride (SF6) in liquid ammonia, yielding metal fluorides.
• Investigating the reaction mechanisms of SF6 degradation is crucial for environmental and industrial applications.

Purpose of the Study:

• To investigate the reaction of atomic metal anions (K- and Ag-) with SF6 using mass spectrometry.
• To elucidate the reaction pathways and product formation at varying collision energies.

Main Methods:

• Generation of atomic metal anions (K- and Ag-) via in-source collision-induced dissociation (CID) of oxalate salts.
• Reaction of metal anions with neutral SF6 in a triple quadrupole mass spectrometer.
• Analysis of reaction products (SF6- and SF5-) as a function of collision energy.

Main Results:

• The primary reaction products observed were SF6- and SF5-.
• At low collision energy, SF5- formation was attributed to fluorine abstraction from SF6- within an encounter complex.
• At higher collision energies, collision-induced dissociation (CID) of SF6- contributed to SF5- formation.

Conclusions:

• The reaction of K- and Ag- with SF6 proceeds via electron transfer and subsequent pathways.
• Collision energy plays a significant role in determining the dominant reaction mechanism (fluorine abstraction vs. CID).
• Understanding these reactions provides insights into SF6 decomposition pathways relevant to its environmental impact.