Module to guide the expert use of x-ray photoelectron spectroscopy by corrosion scientists

Abstract

This contribution, to the potential development of data systems having some degree of “expert” character for use in x-ray photoelectron spectroscopy (XPS), illustrates the manner in which models of “Rules” might be developed by the user community. The field of corrosion science is taken as an example of one community of researchers who make regular use of XPS for well defined needs. These “needs” are redefined as a series of Goals that have to be reached in order to characterize the surface in terms of layer sequences and the enrichment of given elements within them. Rules are written to allow a structured approach to achieve each Goal. A feature of this set of Rules is that they are designed expressly to allow automated interpretation of the survey scan. This approach is facilitated by the use of a recommendation that the survey spectrum be acquired as a series of accumulated scans instead of the usual approach of making a single scan through the spectrum. Repeat scans enable the information extracted by the operation of the Rules to be processed and displayed for information during the period that is normally used for the survey scan. It is intended that this information will inform the setting up of any subsequent high resolution scans and their interactive interpretation. It will also inform any future operations such as ion etching or angle-resolved measurements. In some cases, the information made available may be all that is required by the user and in this case the “expert module” approach becomes particularly cost effective. The operation of the rules is illustrated throughout by an examination of data obtained for passivated stainless steel, giving a data set of measurements, typical of those made by corrosion scientists, that can be compared with the literature values obtained by more conventional XPS interpretation.