Neutron scattering length density profile calculation

Neutron scattering length density profile can be calculated in terms of the known scattering length densities of polymer, pp, and water, p , as... 

Fig. 2.54 Neutron reflectivity profile for a symmetric PS-dPMMA diblock (Mw 30 kg moP1) as a function of incident wavevector (Russell 1990). The inset shows the scattering length density (b/V, the neutron scattering length per unit volume) profile normal to the film surface that was used to calculate the reflectivity profile shown as the solid line, This is typical of a block copolymer film containing a multilayer stack, with lamellae parallel to the surface.

Figure 5 Left NR profiles for a 523.2 nm film of dPS-ft-PMMA symmetric, diblock copolymer as a function of the neutron momentum normal to the surface at the temperatures indicated. The scattering length density fitl/profiles as a function of depth z, where z= 0 is the air surface, shown in the insets were used to calculate the reflectivity profiles drawn as the solid lines in the figures. Right A log-log plot of the difference between T , and the bulk value of Tout, b as a function of film thickness using the value of Toot, b extrapolated from the NR measurements. Reproduced with permission from Menelle, A. Russell, T. P. Anastasiadis, S. H. etal. Phys. Rev. Lett. 1992, 68,67. ...

---