Anisotropic particles phase shifts

In addition to band-edge lasing, defect mode lasing is possible [97]. A defect in the photonic structure creates fine bands of allowed transmissions inside the photonic band gap. A defect may result from an isotropic or anisotropic layer between adjacent cholesteric layers, but also from phase shifts [106], particle stabilized defects [107], deformation of the cholesteric helix [108] or local polymerization [109]. The threshold of such defect modes are low and can be as low as a few nanojoules per pulse [110]. 

In Section II,A, we consider the types of spectra expected for rapid anisotropic motion within a bilayer superstructure (Fig. 6A). It has bwn known for some time that certain lipids will form a completely different type of structure in which the molecules project radially from the center of a cylinder (Fig. 6B Luzzati and Husson, 1962). As mentioned in Section II,B, rapid lateral diffusion within a bilayer phase only affects P-NMR line shapes if the lamellae enclose a particle of small radius. The cylinders in a hexagonal phase have a very small radius, and therefore lateral diffusion about the cylinder axis can cause further averaging of tensor components. The unique axis of the system now becomes the axis of the cylinder, and thus we label its chemical-shift component ap. However, noticing that along this axis the field would be roughly normal to the fatty acyl chains, we would expect the value of this chemical shift to be similar to. On the other hand. 

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