Combined specular and off-specular reflectometry: elucidating the complex structure of soft buried interfaces

Neutron specular reflectometry (SR) and off-specular scattering (OSS) are nondestructive techniques which, through deuteration, give a high contrast even among chemically identical species therefore highly suitable for investigations of soft-matter thin films. Through combination these two techniques, the former yielding density profile in direction normal to sample surface latter depth-resolved in-plane lateral structure, one can obtain quite detailed information on buried morphology length scales ranging from order ångströms ?10 µm. This is illustrated via quantitative evaluation data SR OSS collected time-of-flight (ToF) measurements set films composed immiscible polymer layers, protonated poly(methyl methacrylate) deuterated polystyrene, undergoing decomposition process upon annealing. Joint analysis was performed by use quick robust originally developed algorithm including common absolute-scale normalization both types scattering, which intricately linked, constraining model degree. This, particularly, makes it possible distinguish readily between different dewetting scenarios driven either nucleation growth defects (holes, protrusions etc. ) or thermal fluctuations interface layers. Finally, 2D maps particular cases presented spaces qualitative differences explained, allowing also differentiation structure long-range order, correlated roughness bulk simple inspection prior fits.