Accession Number:

ADA281165

Title:

In-Situ X-Ray Characterization of the Electrolyte-Solid Interface

Descriptive Note:

Final rept. 1 Dec 1989-31 May 1994

Corporate Author:

RENSSELAER POLYTECHNIC INST TROY NY DEPT OF PHYSICS

Personal Author(s):

Report Date:

1994-05-31

Pagination or Media Count:

17.0

Abstract:

Electrochemically controlled surfaces are expected to be very different from those in vacuum due to high electric fields at the electrolyte- metal interface. Microscopic knowledge of that interface is essential in understanding technologically important processes like corrosion and electroplating. Underpotentially-deposited UPD layers of one metal on another are relatively stable, prototypical systems for such research. The Cu atomic- scale environment in a layer of Cu deposited electrochemically on a large polycrystalline Pt electrode has been studied in situ using both fluorescence- detection x-ray absorption spectroscopy XAS and measurements of x-ray reflectivity. Measurements were made on the same layer with the x-ray electric field vector both parallel and perpendicular to the surface normal vector, essential for the determination of the number of neighboring atoms. After a substantial effort in XAS experimental design and technique development, we have obtained significantly higher quality data than others. Moreover, we have achieved a consistent interpretation for these spectra, involving O, Cu, and Pt atoms as near neighbors. Their distances from Cu are identical in the two polarizations, but their amplitudes are different. These differences provide geometrical constraints on models proposed for the structure of the interface. X-ray absorption spectroscopy, Fluorescence-detection x-ray absorption spectroscopy, Buried interfaces, Electrochemistry, Underpotential deposition, Metal monolayers.

Subject Categories:

  • Inorganic Chemistry
  • Physical Chemistry
  • Coatings, Colorants and Finishes
  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE