Computer analysis of ion elastic backscattering: An iterative fitting method

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Abstract
A new approach towards the computer analysis of ion elastic backscattering is introduced, in which the spectrum synthesis method is extended to an automatic iterative procedure. Instead of fitting the spectrum as a whole, parameters such as signal areas, widths, and leading-edge heights, often readily determined from an experimental spectrum, are fitted by corresponding parameters of computer generated theoretical spectra. Usually fewer signals of the elements of the sample are needed than in alternative methods, and the beam dose may be ignored. The number of layers or the number of elements in a layer is not limited. Regardless of the choice of initial approximations, only a few iterations generally suffice to reproduce accurately the given parameters. As a result of successful analysis, the depth profiles of the elements and a theoretical energy distribution identical in all relevant aspects to the experimental spectrum is produced, thus verifying the initial assumptions about the sample. The accuracy of the procedure exceeds or is equal to that of conventional data analysis.