MODEL-INDEPENDENT METHOD FOR RECONSTRUCTION OF SCATTERING-LENGTH-DENSITY PROFILES USING NEUTRON OR X-RAY REFLECTIVITY DATA

A model-independent method is developed for the reconstruction of the scattering-length-density profile of a film on top of a known substrat e or bulk from the measured reflectivity data. The method is first tes ted on simulated reflectivity data calculated from profiles resembling those used in real experiments. It is shown that the method is effect ive in faithfully reproducing the original profiles from the simulated data. The method is then tested on experimental data from four differ ent surface films. It is found again that the method is capable of gen erating physically reasonable profiles whose calculated reflectivities agree to within chi2 = 1 with the measured data. In the tests, detail ed descriptions are also given for the implementation of the method. F inally, a discussion is given with regard to the application of the me thod and the precautions needed for using this method.