Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy
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Updated: May 7, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
Bharat Kumar1, Scott R Crittenden
1Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208, USA.
Abstract:
We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson-Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length.
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