Practical aspects of inverse scattering methods applied to specular reflectivity data

摘要

The deduction of the scattering potential (SP) perpendicular to the surface by specular reflectivity measurements has been traditionally carried out by trial-and-error and non-linear least-squares analysis. Recently, it has become clear that methods can be used that directly invert the data without having to rely on an a priori model. These so-called inverse scattering methods have in common that they use a two-step procedure. The first step consists in finding the phase belonging to the measured amplitude, either experimentally or in some cases numerically; the second step converts the complex reflection coefficient into the scattering potential. Practical applications are still scarce but will become more popular once the possibilities are known and the eventual pitfalls of the data analysis have been explored. This paper describes several problems that are encountered when real data (i.e., not simulated data) are used to directly invert specular reflectivity data. The possibilities for phaseless inverse scattering determinations are investigated. Two experimental cases show how the latter methods may play a complementary role to traditional fitting methods. The effects of instrumental smearing on the obtained SP are treated. Finally, a new solution is proposed for deconvolving the experimental data from the instrumental profile function. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 27]