Synchrotron infrared reflectance microspectroscopy study of film formation and breakdown on copper

Synchrotron far-infrared spectroscopy of corroded steel surfaces using a variable angle of incidence

Far-infrared spectroscopy, using a synchrotron source, has been used to study carbon steel corroded in CO2-saturated brine in the presence and absence of the corrosion inhibitor 2-mercaptopyrimidine (MPY), which allowed the steel surface roughness to be modified. The effect of the angle of incidence (θi, 30-80°) on the band intensity and observed bands of the spectra from these surfaces has been determined. For the MPY-treated steel (low surface roughness) the highest band intensity is observed at high θi (80°) and different bands were observed at different θi. In contrast, for the MPY-free steel (high surface roughness) the highest band intensity is observed at low θi (30°) and spectral content changes were not observed. The results are explained in terms of the roughness of the MPY-treated and MPY-free steels, and their effect on the level of diffusely reflected light of the incident infrared beam.

Quantitative aspects of normalized differential reflectance spectroscopy: Pt(111) in aqueous electrolytes

A theoretical model is herein proposed to account for changes in the normalized differential reflectance, ΔR/R, of well-defined single crystal Pt(111) surfaces|aqueous electrolyte interfaces. It assumes that ΔR/R is proportional to the area of the electrode either bare or covered by neutral and/or nominally charged species and, for a specific type of site, is modulated by the applied potential, E. Correlations between the coverage of the various species and E were obtained from data reported in the literature or by coulometric analysis of linear voltammetric scans. Excellent agreement was found for the adsorption/desorption of hydrogen and that of bisulfate from acidic electrolytes both on bare, and cyanide-modified Pt(111). Also discussed are extensions of this technique in the transient mode involving the reduction of adsorbed nitric oxide, NO, on Pt(111).