Bragg wavenumber

Bragg Wavenumber mi/ui] Bragg Wavenumber rad/m Bragg Wavenumber [rad/m]... 

X-ray diffraction is one of the primary methods to determine the structure of a liquid crystal phase. Nematic phases are characterized by diffuse arcs at small angles which result from local smectic-type order ( cybotactic clusters . Section 5.7.1). Smectic phases are characterized by Bra spots which result from the layer periodicity (Fig. 5.14). In oriented smectic A phases, the Bragg reflections are normal to the layers and their position is reciprocally related to the smectic layer period. If q is the wavenumber defining the peak position, then from Bragg s law (Eq. 1.26) d = Injq. The molecules and layers in a smectic C phase can adopt different mutual orientations depending on how the phase is accessed. If it is obtained by cooling from an SmA phase, the layer orientation is retained and the molecules tilt. Because the layer orientation... 

At small scattering angles 6, inelastic contributions can be neglected and the quasi elastic scattering is dominant. The scattered intensity is mainly described by a process where the ma itude of the wavenumber remains constant ki = k = k and consequently the Bragg relation applies ... 

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