Oxidation of Adsorbed CO on Pt(111) in CO-Saturated Perchloric Acid Aqueous Solutions:  Simultaneous In Situ Time-Resolved Reflectance Spectroscopy and Second Harmonic Generation Studies

Simultaneous normalized differential reflectance spectroscopy (Δ<i>R</i>/<i>R</i>) and second harmonic generation (SHG) has been employed to follow, independently, OH and adsorbed CO (CO_ads) on a single Pt(111) microfacet in CO-saturated aqueous perchloric acidic solutions during voltammetric cycles, leading to the oxidation of CO_ads and subsequent readsorption of CO on the surface. The results obtained are consistent with the disruption of the √19 × √19R19.1° phase just prior to the oxidation of adsorbed CO.