The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paperSpringer is part of Springer Science+Business Media (www.springer.com) v achievement, but also physically very demanding, especially when considering that the author has all the duties of a professor at a chemistry department of a major university! I am sure that the appreciation of the readers will give Marek Orlik the deserved reward and I hope that the monograph will stimulate further studies of this important branch of physical chemistry.

Oscillatory electroreduction of the thiocyanate complexes of nickel(II) at stationary mercury electrodes is complicated by the formation and accumulation of the heterogeneous Ni amalgam and a surface active NiS adsorbate. Consequently, dynamic instabilities observed at such electrodes always have a transient character. To overcome these difficulties, following our previous studies of the Ni(II)-SCN- oscillator, we describe the new experimental approach, based on the application of the streaming mercury electrode to the studies of nonlinear dynamic instabilities of this system. A special experimental setup was assembled. We found that in the presence of an appropriate serial ohmic resistance in the electric circuit, not only the sustained oscillations, but also the bistable behavior in the current−voltage characteristics occurred, which was not reported for this process so far. The experimental diagram of regions of the bistability, monostability and oscillations in the U−R s parameter space is constructed. For the explanation of the bistability, the numerical models were elaborated which quantitatively confirmed the observed phenomena as originating from the coupling of the negative differential polarization resistance with ohmic potential drops.

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paperSpringer is part of Springer Science+Business Media (www.springer.com) v the author has all the duties of a professor at a chemistry department of a major university! I am sure that the appreciation of the readers will give Marek Orlik the deserved reward and I hope that the monograph will stimulate further studies of this important branch of physical chemistry.

The high complexity of the kinetic mechanism of the H(2)O(2)-SCN(-)-OH(-)-Cu(2+) oscillator, involving numerous intermediates, causes the oscillations monitored potentiometrically with gold or glassy carbon electrodes to exhibit opposite phases compared with the oscillations recorded with palladium or platinum electrodes. Following our previous work on the outline explanation of these phenomena, involving the concept of the mixed potential, in this paper, we present their more detailed and advanced study. For that purpose, we built up a simplified but realistic kinetic model of the studied oscillator, involving nine intermediates. Of those nine species, Cu(OH)(3)(-), Cu(OH)(2)(-), and HO(2)(*) were found to be crucial for the explanation of the potentiometric responses of various electrodes, under an additional assumption that the interfacial exchange current density of the HO(2)(*)/HO(2)(-) couple increases in the series GC < Au < Pt. Calculated oscillatory variations of the mixed potential for various model electrodes, compared with experimental results, allowed us to conclude that the potentiometric oscillations are caused largely by the oscillations of the [Cu(OH)(3)(-)]/[Cu(OH)(2)(-)] concentration ratio, irrespective of the electrode material used as a potentiometric sensor. For the Au electrode, the increase of the potential within every oscillatory peak largely reflects the increase in the [Cu(OH)(3)(-)]/[Cu(OH)(2)(-)] ratio. The simultaneous shift of the relatively high Pt electrode potential toward more negative equilibrium potential of the Cu(OH)(3)(-)/Cu(OH)(2)(-) couple is caused by the increase of the exchange current density of the latter couple. Thus, even the opposite phases of the potentiometric oscillations are explainable in terms of the oscillatory behavior of the same redox couple. Understanding of such phenomena is crucial for the proper interpretation of potentiometric data in complex chemical systems.

The electrolysis of rubrene in a thin-layer electrochemical cell leads to formation of electrohydrodynamic (EHD) convection patterns. The well-known electrochemiluminescence produced in this process renders the convective structures clearly visible. The electrochemical mechanism leading to the EHD convection is analyzed. In particular, the importance of ionic salt concentration is elucidated. Example structures are shown, and the basic mechanism of their formation by convective flows is proposed.