Electrochemical Impedance Spectroscopy (EIS) has
become a standard technique in the electrochemists’
toolbox providing detailed information over very wide
time scales and amplitudes. Commercial instruments
are available that can measure impedances from m?
to T? and over frequencies from μHz to MHz.
Most commonly, EIS is measured using a “single-sine”
method where individual frequencies are measured
sequentially. One disadvantage of single-sine EIS is
the time it takes to acquire a full spectrum. A
complete sine wave cycle takes ~17 min at 1 mHz
and ~27 hrs for 10 μHz. This disadvantage can be
overcome by measuring multiple frequencies at the
same time (akin to Fourier transform spectroscopy
techniques).
This application note discusses the use of multiple sine
wave excitation in EIS and its implementation in
Gamry Instrument software. It does not cover the
basics of EIS which are described in the application
note ”Basics of Electrochemical Impedance
Spectroscopy”
(http://www.gamry。。ｃｏｍ/App_Notes/Index.htm).