Wide frequency range impedance measurements are applied to a kinetic investigation of passive iron in various acidic media. Special care was taken in the electrode preparation to reach stable current densities false(7 μA·cm−2 normalin Fe/1M H2SO4,25°Cfalse) . Impedance data were obtained as a function of potential and temperature in the steady state. An original approach to the nonsteady‐state behavior is introduced by combining transient response to the time dependence of the impedance. Contributions from transport in the film and interfacial impedance are separated. The classical view of high field conduction mechanism is refined with respect to the generality of the description and also to the film properties in various environments leading to the concept of chemically dependent high field ion migration. Low frequency behavior in the millihertz range supported this conclusion by ruling out the idea of diffusion‐controlled passive current. The capacitance observed is attributed to the film‐growth kinetics.

The possible use of Raman spectroscopy for studies of anodic corrosion film formation on Fe‐Cr and Fe‐Cr‐Mo single crystals has been elucidated. The study shows that Raman spectra from passive films (thickness range 5–6 nm) and from “transpassive films” or films grown during secondary passivity (thickness range 5–25 nm) can be detected and interpreted. The results from Raman spectroscopy have been obtained in 1MKOH and combined with complementary results from x‐ray photoelectron spectroscopy and nuclear microanalysis. Identified phases in the passive film are α‐false(normalFe,normalCr)2O3 and in the transpassive film α‐false(normalFe,normalCr)2O3 , Fe‐Cr spinel, and amorphous normalFeOOH .

The electrochemical response of Rh/H3SO4(aq) interfaces at 25°C, subjected to different potential-time perturbation programs in the potential range of H and 0 electrosorption and H and 0 electrodesorption is reported . The H electrosorption and H electrodesorption involve the participation of at least two distinguishable adsorption states. The degree of reversibility of the corresponding electrochemical processes is appreciably influenced by the history of the electrode including the type of perturbation applied to the electrode in the 0 electrosorption potential range.The 0 electrosorption and 0 electrodesorption involve the formation of different surface species as it is deduced either from the charge balance or from the kinetic response of the electrochemical interface . The early stages of the anodic reaction are interpreted through a reversible charge transfer comprising the formation of OH adsorbed species which later undergoes electrochemical and chemical reactions yielding different 0-containing species . The existence of the various 0-containing surface species as well as the influence of the most stable ones in the H electrosorption potential range is evidenced through their potentiodynamic electrodesorption . The kinetic results of the 0 electrosorption are discussed in terms of aging mechanisms including anion adsorption .

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