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When the neutron scattering technique, Spin Echo Resolved Grazing Incidence Scattering (SERGIS) concept, was originally put forward by Rekveldt [Physica B 1135, 234-236 (1997)] and Felcher et al. [Proc. SPIE 4785, 164 (2002)], they recognized that the specular scattering and the off-specular scattering could be spatially separated due to the tight neutron beam collimation in the scattering plane, a necessity for any reflectometry experiment. In this Letter, we show that it is possible to make large area measurements of periodic grating structures using SERGIS in a number of interesting scenarios. The SERGIS data can be analyzed using a dynamical theory, which makes it possible to effectively retrieve the lateral profile of a commercial periodic diffraction grating. Interestingly, this is still the case even when that grating is buried beneath a highly deuterated poly(methyl methacrylate-D8) polymer layer. We also clearly demonstrate that the maximum sensitivity to lateral structures is achieved when the specular reflection from the grating is excluded from the data analysis, demonstrating a feature of SERGIS that was proposed over two decades ago. (C) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). STFCScience & Technology Facilities Council (STFC) [RB 1110285]; EPSRC Soft Nanotechnology Platform Grant [EP/E046215/1]; University of Sheffield The spin echo grazing incidence neutron experiments were supported by the STFC via the allocation of experimental time to use OffSpec (No. RB 1110285). A.J.P. was funded by the EPSRC Soft Nanotechnology Platform Grant (No. EP/E046215/1) and subsequently by a fellowship from the University of Sheffield. We thank Mr. Adam Hobson for assistance with the measurements on OffSpec. Dr. Nick Mullin helped with the AFM measurement of the annealed grating. A.J.P. is grateful to Dr. Steven Parnell for reading the draft manuscript and providing helpful comments.

We present a new instrument for spin echo small angle neutron scattering (SESANS) developed at the Low Energy Neutron Source at Indiana University. A description of the various instrument components is given along with the performance of these components. At the heart of the instrument are a series of resistive coils to encode the neutron trajectory into the neutron polarisation. These are shown to work well over a broad range of neutron wavelengths. Neutron polarisation analysis is accomplished using a continuously operating neutron spin filter polarised by Rb spin-exchange optical pumping of (3)He. We describe the performance of the analyser along with a study of the (3)He polarisation stability and its implications for SESANS measurements. Scattering from silica Stöber particles is investigated and agrees with samples run on similar instruments.

Neutron spin echo resolved grazing incidence scattering (SERGIS) was used to probe crystallites of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) produced by extensive thermal annealing of a poly(3-hexylthiophene-2,5-diyl)(P3HT):PCBM organic photovoltaic layer. After annealing a thin film of P3HT:PCBM, PCBM crystallites appear on the sample surface, and a strong SERGIS signal is observed superimposed on the specular reflection. Features in the data can be readily correlated with length scales of the crystallites determined using atomic force microscopy and indicate that in such cases the SERGIS signal may be interpreted as a form of small angle neutron scattering.