Electric-field-directed alignment

The electric field of plane-polarized light oscillates in a single plane. It can be prepared hy passing ordinary, unpolarized light through a polarizer, which consists of a material that allows the light to pass only if the electric field is aligned in a certain direction. 

The model predicts that for the typical elastic parameters the polarization splay is small, just a few degrees. This was also confirmed experimentally as only a small change of birefringence under the electric field is detected for the Blrev phase. The electric field eliminates the spontaneous splay by aligning the dipole moments along the electric field direction. 

Bow tie trees (Figure 16) can be of either electrical or electrochemical nature in origin. They are initiated at voids or contamincuits not connected to either the conductor shield or to the insulation shield. They are aligned parallel to the electrical field direction. 

In a homogeneous electric field, such a wave function will not be a constant but will have a single maximum for the electric field direction (and the minimum for the opposite direction). For any field intensity, this will correspond to the state of the lowest energy. This is namral because a dipole should have a tendency to align along the orientation of the electric field. 

Yuegang Z, Aileen C, lien C, Qian W, Woong K, Yiming L, et al. Electric-field-directed growth of aligned single-walled carbon nanotubes. Appl Phys Lett 2001 79 3155-7. 

FIGURE 28 Transmission electron micrographs of microtome slices of an aligned PS-PMMA block copolymer sample. In (a), the slice plane was perpendicular to the electric field direction, and in (b) and (c) the slice plane contained the electric field direction. Intersection of the slice plane with +1/2 and -1/2 disclination lines and wall defects (denoted with a w ) are indicated in (a). (Reprinted with permission from Ref. 65.)... 

When an electric field is applied, a force to orient the molecules towards the electric field direction conflicts with the intermolecular interaction. The higher the electric field, the more the dipole of the liquid crystal molecules aligns towards the direction of the electric field. If the electric field is weakened, the effect to attempt the return of the molecules to the ground state becomes stronger and as a result, the polarization reversal current is maximum at the central position near zero voltage. 

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