Surface thermodynamic origin

The Frumkin epoch in electrochemistry [i-iii] commemorates the interplay of electrochemical kinetics and equilibrium interfacial phenomena. The most famous findings are the - Frumkin adsorption isotherm (1925) Frumkin s slow discharge theory (1933, see also - Frumkin correction), the rotating ring disk electrode (1959), and various aspects of surface thermodynamics related to the notion of the point of zero charge. His contributions to the theory of polarographic maxima, kinetics of multi-step electrode reactions, and corrosion science are also well-known. An important feature of the Frumkin school was the development of numerous original experimental techniques for certain problems. The Frumkin school also pioneered the experimental style of ultra-pure conditions in electrochemical experiments [i]. A list of publications of Frumkin until 1965 is available in [iv], and later publications are listed in [ii]. 

From the thermodynamic point of view surface or interfacial tensions are intensive parameters and their value does not depend on the extension of the interface. Originating in the physics and chemistry of surfaces, surface thermodynamics is now an independent field. 

Another phenomenon, also of thermodynamic origin, is the wetting that occurs during the adhesive interaction. The wetting is defined as the spontaneous movement (or forced movement whenever the process is deliberately caused) of the system energy, which accompanies the components interactions. It has as quantitative parameter, the contact angle between the drop surface and that of solid one, respectively. The contact angle is noted by q for the systems in equilibrium and by / for those far from equilibrium [1233]. 

However, making an even small step to qualitative assessment of availability of active particles on the surface under regular thermodynamic conditions is difficult. This is especially difficult if we are faced with the problem of quantitative evaluation of particles origin and role in specific heterogeneous processes. 

The physical origin of this structural flexibility of the FeO overlayer is still unclear, the more so since no clear trend is observable in the sequence of lattice parameters of the coincidence structures. The FeO(l 11) phase forming up to coverages of 2-3 ML is clearly stabilized by the interactions with the Pt substrate since FeO is thermodynamically metastable with respect to the higher iron oxides [106,114], FeO has the rock salt structure and the (111) plane yields a polar surface with a high surface energy [115], which requires stabilization by internal reconstruction or external compensation. The structural relaxation observed in the form of the reduced Fe—O... 

A quantity of central importance in the study of uniform liquids is the pair correlation function, g r), which is the probability (relative to an ideal gas) of finding a particle at position r given that there is a particle at the origin. All other structural and thermodynamic properties can be obtained from a knowledge of g r). The calculation of g r) for various fluids is one of the long-standing problems in liquid state theory, and several accurate approaches exist. These theories can also be used to obtain the density profile of a fluid at a surface. 

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