C.A. Melendres

In-situ synchrotron far infrared spectroscopy of surface films on a copper electrode in aqueous solutions.

Abstract Far infrared spectra of the surface films formed upon anodic oxidation of copper have been obtained in-situ for the first time in aqueous solution environments using a synchrotron source. The spectroelectrochemical behavior of copper was studied in NaOH and in a dilute solution of KSCN in perchlorate. The oxide film at −0.05 V vs. SCE in 0.1 M NaOH solution has been identified as Cu 2 O. In the passive region at 0.3 V, CuO and Cu(OH) 2 appear to be present on the surface. Vibrational bands observed in 0.025 M KSCN+perchlorate solution are attributed to a multilayer film of copper(I) thiocyanate.

On the composition of the passive film on nickel: a surface-enhanced Raman spectroelectrochemical study

Abstract The composition of the surface film on nickel in the passive potential region has been determined using the technique of surface-enhanced Raman spectroscopy with electrodeposited silver. Both Ni(OH)2 and NiO were found to be present. The formation of these species is correlated for the first time with the two anodic waves in the voltammogram of nickel in all the solutions studied from pH 2.7 to 12. Ni(OH)2 is formed first, and then NiO at a more anodic potential. A duplex-type film consisting of an inner NiO layer and an outer Ni(OH)2 layer appears to be the most consistent model for the passive film on nickel.

Cell design for in—situ X-ray scattering study of electrodes in transmission geometry

A novel electrochemical cell that permits in—situ X-ray scattering studies in transmission geometry for the examination of electrode/electrolyte interfaces is described. The advantages of this geometry over others used presently are discussed, and initial experimental results are reported on the electrochemical formation of passive oxide film on silver.

‘In-situ’ observation of halide ion adsorption on a gold electrode using synchrotron far infrared spectroscopy

Abstract The adsorption of chloride and bromide ions on a gold electrode in the double layer region in 0.5 M perchloric acid solution was observed ‘in-situ’ for the first time using the technique of synchrotron far infrared reflectance spectroscopy (SFIRS). The Au–Cl surface vibrational frequency was measured to be about 263 cm −1 in chloride concentrations from 0.005 to 0.05 M. The Au–Br stretching mode was observed at 182 cm −1 . The SFIRS technique is a promising tool for the investigation of interfacial electrochemical structures and processes with monolayer sensitivity.

A laser Raman spectroscopic study of anodic corrosion films on silver and copper

Nouvelles donnees eu egard aux processus de corrosion obtenus a partir des etudes experimentales de dissolution de Ag et Cu en milieu sulfate

SPECULAR X-RAY REFLECTION FOR THE 'IN SITU' STUDY OF ELECTRODE SURFACES

We wish to report here the results of a study of the state of copper surfaces «in situ» during electrochemical polarization in aqueous solution environments. We demonstrate in this work that valuable information on the formation and reduction of surface films, as well as the density, thickness, and interface roughness of the corrosion layers formed, can be obtained from X-ray reflectivity studies. The information on atomic-scale roughness of buried interfaces cannot be obtained by any other technique

High-temperature “in-situ” surface Raman spectroelectrochemistry in aqueous solutions

Etude, au moyen de ces methodes couplees, de la corrosion et de la passivation du plomb dans une solution de sulfate tres diluee, de 25 a 290°C et a 100 atm.

Synchrotron far infrared spectroscopy of surface films on a copper electrode in aqueous solutions.

Abstract Far infrared (IR) spectra of the surface films on copper have been obtained “in situ” in aqueous solution environments using a synchrotron source. The oxide film on copper at −0.05 V vs. SCE in 0.1M NaOH solution has been identified as Cu2O. In the passive region at 0.3 V, CuO and Cu(OH)2 appear to be present on the surface. In dilute solutions of KOCN in perchlorate, vibrational bands have been observed that could be attributed to a few monolayers of Cu(OCN)2.

Difference Raman spectroscopy for “in-situ” analysis of electrode surfaces

La spectroscopie Raman par difference comprenant lelimination de leffet de la fenetre et du volume de la solution est utilisee pour analyser la surface de lelectrode

The Adsorption of CO and H2O on Polycrystalline Gold, as Studied by Synchrotron Infrared Spectroscopy

Synchrotron infrared spectra of CO and H2O adsorbed on a polycrystalline (pc) gold surface have been obtained for the first time Assignments were confirmed through isotopic shifts measurements with 13CO and D2O. Surprisingly, CO was found to adsorb on (pc) gold over a wide range of temperatures well above the limit of a few K generally accepted in the literature. CO adsorption occurred on mostly atop sites characterized by a strong C-O stretching mode at 2111 cm−1. A maximum absorption intensity of 3% was measured at 132 K and a surface coverage of 5 to 20 L. But despite repeated efforts, no reproducible Au-C stretching vibrations were detected.