Neutron from monolayer films

Grundy, M. J Richardson, R. M., Roser, S. J., Penfold, J. and Ward, R. C. (1988). X-ray and neutron reflectivity from spread monolayers. Thin Solid Films 159 43-52. 

Unique information about the unit cell in quasi-crystaUine monolayers can be obtained from X-ray °, neutron , heUum or low energy electron diffraction (LEED) data. In the grazing incidence X-ray diffraction (GIXD) experiment the beam is directed at the coated surface at a low angle and experiences total internal reflection from the metal support underneath the monolayer. The analysis of reflectivity and diffraction pattern of this reflected beam provides information about the molecular structure of the crystalline films, the thickness and refractive index of the layers and the roughness of the surface s . These experiments, however, require sophisticated and expensive equipment and are not therefore used routinely for monolayer characterization. 

Neutron reflectometry has been applied to three classes of polymer systems (1) polymers adsorbed from solution to an interface (generally the solid-liquid interface) (2) solid polymer films and (3) polymers spread as monolayers. Russell [56] has surveyed results up to mid-1990, and so attention here is concentrated on results obtained since that time. 

We remind that the intensity of off-specular scattering is based on the neutron interference field inside the polymer film. It is mainly the interference between Kj and k/, followed by multiple reflections, which create this intensity field for the model of a monolayer as can be deduced from Figure 8. The distribution of the intensity field of a multilayer is shown in Figure 12 for the multilayer in Figure 6(c) without nanoparticles. Two examples highlight the influence of this intensity field. The PBMA layers exhibit internal high neutron intensity at aj = 2.7 mrad, the position of the aitical angle of the... 

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