Experimental feasibility of phaseless inverse scattering methods for specular reflectivity

The possibilities for calculating the X-ray or neutron scattering potential across a thin film from experimental specular reflectivity amplitude information alone and using full dynamical theory, i.e., phaseless inverse scattering, are investigated and compared with traditional fitting methods. The feasibility of the method is demonstrated by one trivial and two non-trivial experimental examples. The usefulness, but also the limitations are outlined by the experiments and by numerical examples. The data reduction is treated in some detail and, in particular, a new method is proposed for deconvolving the experimental data from the instrumental smearing function.