Molecular properties affecting the hydration of acid-base clusters

Area of Science:

• Atmospheric Chemistry
• Physical Chemistry
• Environmental Science

Background:

• Water's ubiquitous presence in the atmosphere influences chemical reactions and aerosol composition.
• Direct measurement of water clusters is challenging due to evaporation.
• Theoretical studies are essential for understanding atmospheric hydration.

Purpose of the Study:

• Investigate the thermodynamics and population dynamics of hydration for atmospheric bases and sulfuric acid-base pairs.
• Explore the mechanisms of proton transfer reactions at water-air interfaces.
• Determine factors influencing sulfate formation in hydrated clusters.

Main Methods:

• Computational study of thermodynamics and population dynamics.
• Analysis of hydration of base monomers and sulfuric acid-base pairs.
• Thermodynamic study of proton transfer in water clusters (up to 20 water molecules).

Main Results:

• Base hydration ability correlates with gas-phase base strength.
• Acid-base cluster hydration depends on hydrogen binding sites.
• Proton transfer in water clusters relates to aqueous-phase basicity.
• Sulfate formation is most favorable with dimethylamine in hydrated clusters.

Conclusions:

• Hydration and proton transfer in atmospheric clusters are governed by molecular properties like base strength and hydrogen bonding.
• Dimethylamine plays a key role in sulfate formation within hydrated clusters.
• Theoretical modeling provides critical insights into atmospheric water cluster behavior.