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Relaxation processes due to the electrode-electrolyte interface in ionic solutions.

Authors
  • Sanabria, Hugo
  • Miller, John H Jr
Type
Published Article
Journal
Physical Review E
Publisher
American Physical Society (APS)
Publication Date
Nov 01, 2006
Volume
74
Issue
5 Pt 1
Pages
51505–51505
Identifiers
PMID: 17279915
Source
Medline
License
Unknown

Abstract

One of the major challenges in electrochemistry is to properly account for polarization of the electrical double layer that forms at an electrode-electrolyte interface, especially when interpreting the impedance spectra of biological molecules, electrolytes, or live cell suspensions. This double layer, which affects the measured impedance, is also known as the electrode polarization effect. Various methods of correcting for its effects on impedance data have been reported, including varying the spacing between electrodes, four-electrode techniques, and electrodeless methods. Here we discuss the use of a constant phase element in a recently proposed circuit model, which can be thought of as a measure of the fractal nature of the interface. We also report on the conductivity spectra of several saline solutions over the frequency range 1 Hz-1 MHz, in which we observe Debye-like relaxation behavior that changes with ion concentration and type. Good agreement is obtained with an alternative model that treats the cations and anions as overdamped oscillators in harmonic restoring potentials.

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