Radial configuration, nematics

Assume a point disclination located in a nematic droplet of radius R. The point disclination can be classified according to their Poincare characteristic angle a as a knot point (a = 0), focus point (0 < a < 7t/2), center (a = 7t/2), saddle-focus point (tt/2 < a < tt) or saddle point (a = 7t/2). For a knot point, one has a spherically symmetrical radial configuration and then... 

NMR, and particularly deuterium NMR, are the best experimental techniques for the determination of the director field and the molecular dynamics in submicron nematic droplets. The theoretical static proton NMR spectra of the nematic micro-droplets for a bipolar and a radial configuration are shown in Fig. 17 a. The corresponding motionally averaged spectra are shown in Fig. 17 b. Here the motional averaging is produced by translational diffusion which induces slow molecular rotations due to the non-uniform orientational ordering in the droplet [206]. 

Figure 17. (a) Simulated static proton NMR spectra of nematic microdroplets for the bipolar (NqIIHo) radial configurations, (b) Dynamic proton NMR spectra for (1) the bipolar (No /lo) and (2) the radial director configurations [206]. For = 50 the diffusion is slow whereas for e = 0.05 the diffusion is fast. Here e =A r lD with 2A being the static line splitting. 

FIGURE 4.46. Different configurations of the director inside the nematic droplet [257-260]. (a) Biaxial application of the field results in rotation of the symmetry axis (b) radial or starlike configuration (E = 0) transforms into the axial one in a sufficiently high field (c) toroidal distribution and (d) twisted configuration. 

Figure 16. Bipolar (a) and radial (b) configuration of the nematic molecular directors in polymer dispersed nematic microdroplets [2021.

Figure 19. Schematic lepresentation of nematic director configurations for the (a) planar radial, (b) planar polar, and (c) escaped radial nematic structures in microcylinders [215].

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