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Polarization charge: Theory and applications to aqueous interfaces
Bobo Shi1, Mithila V Agnihotri1, Si-Han Chen2
1Biophysics Program, Ohio State University, Columbus, Ohio 43210, USA.
The Journal of Chemical Physics
|May 2, 2016
Summary
This study reveals that dielectric polarization charge layers are not infinitely thin but distributed over a nanometer-scale region at aqueous interfaces. Molecular-level analysis provides new insights into electrokinetic phenomena.
Area of Science:
- Physical Chemistry
- Materials Science
- Nanotechnology
Background:
- Dielectric polarization charge layers are theoretically assumed to be infinitely thin.
- This assumption is prevalent in macroscopic dielectric theory and nanoscale electrokinetic studies.
- A molecular-level understanding of these charge layers is lacking.
Purpose of the Study:
- To investigate the molecular details of polarization charge layers at aqueous interfaces.
- To present formal relations and linear response theory for polarization charge.
- To determine the spatial distribution and width of the polarization charge layer.
Main Methods:
- Development of formal relations and linear response theory for polarization charge.
- Equilibrium molecular simulations using linear response theory.
- Non-equilibrium molecular simulations.
- Analysis of three aqueous interfaces: air-water, crystalline silica-water, and amorphous silica-water.
Main Results:
- The polarization charge is found to be distributed over a region approximately one nanometer wide.
- Calculations from both equilibrium and non-equilibrium simulations show consistent results within statistical error.
- Detailed molecular properties of the polarization charge layer are elucidated.
Conclusions:
- Polarization charge layers at aqueous interfaces possess a finite, nanometer-scale width.
- The findings challenge the infinitely thin layer assumption in electrokinetic phenomena.
- This molecular-level understanding is crucial for nanoscale transport and interfacial phenomena.
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