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Lookup NU author(s): Professor Mark GeogheganORCiD
This is the authors' accepted manuscript of an article that has been published in its final definitive form by Wiley-Blackwell Publishing Ltd, 2021.
For re-use rights please refer to the publisher's terms and conditions.
Neutron specular reflectometry (SR) and off-specular scattering (OSS) are nondestructive techniques which, through deuteration, give a high contrast even among chemically identical species and are therefore highly suitable for investigations of soft-matter thin films. Through a combination of these two techniques, the former yielding a density profile in the direction normal to the sample surface and the latter yielding a depth-resolved in-plane lateral structure, one can obtain quite detailed information on buried morphology on length scales ranging from the order of ångströms to ∼10 µm. This is illustrated via quantitative evaluation of data on SR and OSS collected in time-of-flight (ToF) measurements of a set of films composed of immiscible polymer layers, protonated poly(methyl methacrylate) and deuterated polystyrene, undergoing a decomposition process upon annealing. Joint SR and OSS data analysis was performed by the use of a quick and robust originally developed algorithm including a common absolute-scale normalization of both types of scattering, which are intricately linked, constraining the model to a high degree. This, particularly, makes it possible to distinguish readily between different dewetting scenarios driven either by the nucleation and growth of defects (holes, protrusions etc.) or by thermal fluctuations in the buried interface between layers. Finally, the 2D OSS maps of particular cases are presented in different spaces and qualitative differences are explained, allowing also the qualitative differentiation of the in-plane structure of long-range order, the correlated roughness and bulk defects by a simple inspection of the scattering maps prior to quantitative fits
Author(s): Hafner A, Gutfreund P, Toperverg BP, Jones AOF, de Silva JP, Wildes A, Fischer HE, Geoghegan M, Sferrazza M
Publication type: Article
Publication status: Published
Journal: Journal of Applied Crystallography
Year: 2021
Volume: 54
Issue: 3
Pages: 924-948
Print publication date: 01/06/2021
Online publication date: 31/05/2021
Acceptance date: 02/04/2021
Date deposited: 05/08/2021
ISSN (print): 0021-8898
ISSN (electronic): 1600-5767
Publisher: Wiley-Blackwell Publishing Ltd
URL: https://doi.org/10.1107/S1600576721003575
DOI: 10.1107/S1600576721003575
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