Potentiodynamic electrochemical impedance spectroscopy (PDEIS) is the technique for versatile characterisation of electrochemical responses of interfacial processes and structures. PDEIS acquires variable frequency responses in alternating current and a potentiodynamic dc voltammogram in the same potential scan, by probing the electrochemical interface with streams of mutually coordinated wavelets.

PDEIS virtual spectrometer program acquires a potentiodynamic impedance spectrum by a common potentiostat connected to a computer with ADC/DAC interface. The object is placed in a common three-electrode electrochemical cell and the spectra are usually recorded in bidirectional potential scans, which give additional information on the extent of reversibility of different constituent processes that contribute to the frequency response of a nonstationary electrochemical interface.

Virtual instruments implement both the acquisition and analysis of the potential-dependent electrochemical response. In the potential scan, the multivariate data analysis gives a PDEIS spectrum and a voltammogram in a 3D plot on a computer screen. After the scan, a built-in equivalent electric circuit analyser decomposes the ac part of the interface response into constituents related to different interfacial processes and structures. Thus, potentiodynamic electrochemical impedance spectroscopy characterises, in a single potential scan, different interrelated processes (interfacial charge transfer, diffusion, adsorption, etc.) and interfacial structures (double electric layer, space charge layers, etc.) at non-stationary electrochemical interface. The separation of the constituent ac responses has enabled multiparametric monitoring of atomic layer-by-layer deposition in multilayer assembly, characterisation of nonstationary semiconductor systems by acquisition of variable Mott-Schottky plots, monitoring of nonstationary stages of electropolymerisation and mutually correlated adsorption of cations and anions.