Elemental sulfur aerosol-forming mechanism

Area of Science:

• Astrobiology
• Atmospheric Chemistry
• Planetary Science

Background:

• Elemental sulfur aerosols are prevalent in the atmospheres of Venus, ancient Earth, and Mars.
• Evidence suggests these aerosols influenced the evolution of early life on Earth.
• The precise formation mechanism of these sulfur aerosols remains poorly understood.

Purpose of the Study:

• To elucidate the chemical mechanism behind the formation of elemental sulfur aerosols.
• To investigate the role of sulfur oxides and hydrogen sulfide in aerosol genesis.
• To provide a framework for understanding sulfur aerosol formation in diverse planetary environments.

Main Methods:

• Theoretical calculations were employed to model chemical reactions.
• The study focused on the interaction between sulfur oxides (SO_n) and hydrogen sulfide (nH₂S).
• Reaction pathways were analyzed under conditions of water and sulfuric acid catalysis.

Main Results:

• A novel chemical mechanism for efficient formation of S_n+1 particles was identified.
• The SO_n + nH₂S → S_n+1 + nH₂O reactions proceed via low-energy pathways.
• Formation of larger polysulfur aerosols through nucleation of S_n+1 particles was demonstrated.

Conclusions:

• The proposed chemical mechanism provides a plausible explanation for elemental sulfur aerosol formation.
• This pathway is effective under catalytic conditions relevant to planetary atmospheres.
• The findings offer insights into the chemical environment supporting early life on Earth and other planets.