Characterization and Atmospheric Implication of Hydrotrioxy Radical-Water-Methylamine-Formic Acid-Sulphuric Acid...

Area of Science:

• Atmospheric Chemistry
• Aerosol Science
• Quantum Chemistry

Background:

• New particle formation is a key source of atmospheric aerosols, significantly impacting climate and air quality.
• The precise mechanisms of nucleation, particularly involving the hydroperoxyl radical (HOOO•), remain incompletely understood.
• Understanding molecular interactions is crucial for modeling atmospheric aerosol processes.

Purpose of the Study:

• To investigate the formation of bimolecular complexes between the HOOO• radical and various atmospheric molecules (H2O, CH3NH2, HCOOH, H2SO4).
• To explore the stabilizing effects of these molecules on the HOOO• radical.
• To examine the subsequent hydration of stable 1:1 complexes and their impact on atmospheric chemistry.

Main Methods:

• Employed quantum chemical methods to study the energetics and stability of molecular complexes.
• Calculated equilibrium constants for complex formation.
• Analyzed spectroscopic properties, specifically the IR intensity of OH stretching vibrations.

Main Results:

• Bimolecular complex formation between HOOO• and CH3NH2 or H2SO4 is spontaneous under atmospheric conditions.
• Methylamine and sulfuric acid exhibit comparable stabilizing effects on the HOOO• radical.
• Water significantly stabilizes the HOOO•…H2SO4 complex, with complexation being spontaneous and affecting IR spectra.

Conclusions:

• The stabilization provided by methylamine and sulfuric acid is critical for HOOO• radical interactions in new particle formation.
• Hydration further enhances the stability of key complexes, influencing aerosol formation pathways.
• These findings provide essential data for understanding tropospheric aerosol composition and formation dynamics.