Application of Mössbauer Spectroscopy to in Situ Studies of the Anodic and Cathodic Behavior of Cobalt Surfaces

Abstract

The anodic behavior of metals is a complex phenomenon, particularly for experimental conditions that produce passivation of the metal surfaces. Because of the limited experimental techniques available for in situ studies of surface films, there remains considerable uncertainty about many aspects of passivation and anodic behavior of metals. Electrochemical methods have been useful in characterizing the anodic behavior of metals, but these techniques have not provided unambiguous information about the chemical composition and structure of anodically-produced surface films. The non-electrochemical approaches used thus far have also been of limited value. Electron diffraction investigations require that the specimen be removed from its initial environment, and reasonable objections to the interpretation of results can be raised because of possible changes in composition of the specimen surface, such as dehydration, that may occur during the diffraction analysis. Although ellipsometry is a highly surface sensitive technique and is applicable to in situ studies, the measured parameters of thin films, 10–50 A, lead only to information about the thickness.