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Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy
Published on: August 13, 2019
Size-resolved sea spray aerosol particles studied by vibrational sum frequency generation
Carlena J Ebben1, Andrew P Ault, Matthew J Ruppel
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
The Journal of Physical Chemistry. A
|July 4, 2013
Summary
Sea spray aerosol particles likely contain disordered surfactants, impacting their surface chemistry and permeability. This suggests more gas exchange than previously assumed, challenging simple particle models.
Area of Science:
- Atmospheric Chemistry
- Surface Science
- Aerosol Science
Background:
- Sea spray aerosol (SSA) particles play a crucial role in Earth's climate.
- Understanding the surface composition and properties of SSA is vital for accurate climate modeling.
- Previous models often simplify the complex organic layers present on SSA.
Purpose of the Study:
- To investigate the molecular structure and orientation of organic species on SSA surfaces.
- To determine the impact of surfactants on SSA particle properties.
- To assess the permeability of SSA surfaces to gas exchange.
Main Methods:
- Vibrational sum frequency generation (SFG) spectroscopy was employed.
- SFG spectra were collected from size-selected SSA particles.
- Comparison of SSA spectra with wave flume microlayer spectra.
Main Results:
- SFG spectra indicate the presence of surfactants in the topmost layer of SSA particles.
- Alkyl chains of surfactants on SSA are likely disordered, not well-aligned.
- SSA particle surfaces exhibit broader molecular orientation distributions than expected.
- SFG data suggest a one-component model is insufficient for SSA.
- Spectra from SSA and wave flume microlayer show similarities in chemical environments.
Conclusions:
- Surfactant-rich SSA particles have disordered alkyl chains, influencing surface properties.
- The permeability of organic layers on SSA may be substantial, enhancing gas exchange.
- SSA surface chemistry is complex and requires multi-component models.
- The surface of SSA may resemble the sea surface microlayer compositionally.
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