X-RAY-ABSORPTION SPECTROSCOPY - A PROBE FOR THE IN-SITU STUDY OF FILMS DEPOSITED AT A METAL ELECTROLYTE INTERFACE

X-ray absorption spectroscopy (XAS) is a sensitive method for determin ing the oxidation state and the local order of an element under study when it is dissolved in a matrix or deposited on the surface of a subs trate of various nature. In the case of grazing incidence and fluoresc ence detection, this method can be used for the in situ study of the s tructural properties of a film found in a condensed medium. This metho d makes it possible to obtain the chemical and structural characterist ics of monolayers electrochemically deposited at a metal/electrolyte i nterface and fractions of such monolayers. A method which was develope d in the DCI storage ring and in LURE (Laboratoire pour l'Utilisation du Rayonnement Electromagnetique) for studying copper and zinc systems at the potentials for deposition on single-crystal gold substrates ha s been described The effect of the crystallographic orientation of the substrate and the coverage of the structure with the adsorbate has be en studied in the Cu/Au system. The formation of a very stable zinc-co pper compound, which can be oxidized only at very positive potentials, has been demonstrated in the Zn/Au system.