Advances in specular neutron reflectometry

Abstract

Specular neutron reflectometry provides a depth profile of the scattering length density (SLD) and, ultimately, of the chemical and magnetic composition of a layered material. To date, numerous productive applications of neutron reflectometry have been demonstrated. With the new development of methods for phase determination, the problem of deducing unambiguous SLD profiles from reflectivity data has been solved in principle and, largely, in practice. Nonetheless, the fact that reflectivities can only be measured up to a finite maximum wavevector transfer Q still limits the spatial resolution attainable. Currently, neutron reflectivities as low as 10-8 out to values of Q approaching 0.7 A-1 can be measured, yielding spatial resolutions of a fraction of a nanometer. We examine the current sensitivity of neutron reflectometry and consider approaches, both instrumental and analytical, for effectively extending the Q range.