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Electrochemistry The Bookstore Tell Us ! |
Whenever you look at a Complex-Plane Impedance Plot (
Nyquist or Cole-Cole plot) and see a 45° line, or fit data to an equivalent circuit and find a
)
as you would expect for a CPE with an n-value of 0.5. The
Warburg is unique among CPE's because the real and imaginary components are
equal at all frequencies and both depend upon 
) is a bit more complicated and will be discussed on
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A fairly readable derivation of these equations can be found in Bard's book
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We
are often suspicious of "diffusion controlled" experiments in aqueous solutions which
last more than a few seconds because of the possibilities of convection and
stirring at these long times. For exactly the same reason, we should also be suspicious of EIS
experiments in aqueous solutions taken at frequencies less than 0.1 Hz if we expect a
"diffusion controlled" Warburg impedance!
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Electrochemistry The Bookstore Tell Us ! |
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A fairly readable derivation of these equations can be found in Bard's book
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