Inverting neutron reflectivity from layered film structures using polarized beams

It has recently been discovered that the phase of neutrons specularly refle cted from a film structure can be determined exactly, even in the dynamical scattering region at small wave vector transfer, by using polarized beams and a buried magnetic reference layer. This is possible for both magnetic a nd nonmagnetic material films of interest. Given the reflection amplitude a s a function of wave vector transfer, the scattering potential can be uniqu ely obtained by direct inversion, without resort to fitting. A review of so me of the theory is presented, and new experimental results are reported. ( C) 1999 Published by Elsevier Science B.V. All rights reserved.