Analysis of x-ray reflectivity data from low-contrast polymer bilayer systems using a Fourier method

X-ray reflectivity data of polymer bilayer systems have been analyzed using a Fourier method which takes into account different limits of integration in q-space. It is demonstrated that the interfacial parameters can be deter mined with high accuracy although the difference in the electron density (t he contrast) of the two polymers is extremely small. This method is not res tricted to soft-matter thin films. It can be applied to any reflectivity da ta from low-contrast layer systems. (C) 2000 American Institute of Physics. [S0003- 6951(00)03719-0].