The feasibility of an XPS expert system demonstrated by a rule set for carbon contamination

A 'surface analysis', no matter how well authenticated, is rarely satisfying as a single piece of information. Many users require the quantified distribution of observed species as a function of depth. In this paper it is argued that adding knowledge-based inferencing to the data-system is required if the full interpretation of spectra is to be made possible. The basic principles of an expert system are introduced and a preliminary set of rules for the recognition of carbon as a contamination overlayer are proposed. Both the logical steps taken by the expert system in progressing towards identification of the C peak as overlayer contamination and the scientific knowledge on which each rule is based are explained. Once identified as contamination, use of this information in proceeding further with the expert system analysis is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.