The study of interfacial phenomena using impedance measurements in conjunction with complementary techniques

It is explained why and how in particular cases additional information from complementary methods should be used to validate and to improve the information obtained from impedance measurements. As an example we present the direct determination of charge density vs potential curves with a newly developed dropping mercury micro electrode, and its application to prove the specific adsorption of the alkali ions at the mercury / aqueous solution interface. As a second example the study of electrode reactions with a finite rate of charge transfer and complicated by adsorption of the reactant is discussed. Here the combination of impedance measurements with high frequency demodulation measurements is indispensable. This is illustrated by some results for the system (TI (I) / Tl (Hg) in 1 M HCI O4.