title: In situ, time-resolved normal incidence reflectance spectroscopy of polycrystalline platinum microelectrodes in aqueous electrolytes.
abstract: In situ normal incidence reflectance spectra of polycrystalline Pt microelectrodes have been monitored as a function of the applied potential in aqueous 0.5 M H(2)SO(4) using a He-Ne laser source (633 nm) and a beam splitter/microscope objective arrangement. Data recorded during voltammetric cycles in Ar-purged solutions revealed a linear correlation between the normalized change in reflectance, DeltaR/R = (R(s) - R(ref))/R(ref) (where R(s) and R(ref) are the light intensities measured by the detector at the sampling, s, and reference potentials, ref, respectively), and the extent of oxidation of the Pt surface over a wide coverage range. Reflectance spectra were also collected in CO-saturated 0.5 M H(2)SO(4) during chronocoulometric measurements involving judiciously selected limits for both the potential step and duty cycle parameters. Analysis of these results made it possible to extract contributions to the current derived from oxide formation during oxidation of adsorbed and bulk CO, based strictly on the optical response.
authors.forename: Iosif
authors.initials: I
authors.lastname: Fromondi
authors.forename: Ping
authors.initials: P
authors.lastname: Shi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mineshige
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Scherson
mesh_terms: D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry; D003460:Crystallization; D004563:Electrochemistry; D004573:Electrolytes / Q000737:chemistry*; D007834:Lasers; D008839:Microelectrodes; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000379:methods; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D004573:Electrolytes; D014867:Water; D010984:Platinum; D002248:Carbon Monoxide