MECHANISM OF ACTIVE DISSOLUTION OF IRON AND FORMATION OF ITS SURFACE-STRUCTURE - THE ROLE PLAYED BY ADSORPTION OF WATER AND OXYGEN

A mechanism is discussed of active dissolution of iron, which is dynam ically (reversibly) passivated by adsorbed oxygen atoms O-ads. Time ch aracteristics of the iron electroreflectance spectra related to water adsorption are compared with the literature data on the kinetics of th e single-crystal iron dissolution. The conclusion is drawn on the basi s of the comparison that, in acidic solutions, dissolution of iron in half-crystal positions (kinks) does not involve solution components wh ereas in sources of kinks and monoatomic steps, it involves adsorption of water and products of water's interaction with the surface. The fo rmation of O-ads is shown to affect the surface structure of dissolvin g iron, giving rise to disruptions in the steps and to random distribu tion of pyramids that form in the course of the dissolution process.