Surface fields, alignment

Reuter MG, Sukharev M, Seideman T (2008) Laser field alignment of organic molecules on semiconductor surfaces toward ultrafast molecular switches. Phys Rev Lett 101 (20) 208303... 

Treatment of the above SHG curves for membranes 80, 83, 85, and 86 by a Langmuir-isotherm type analysis indicates Langmuir-type saturation occurring at the membrane surface at high cation concentrations, which may be interpreted in terms of a tightly packed monolayer of the SHG active cation complexes at the membrane surface. However, the SHG active layer may actually have a thickness of several monolayers if the electrical field aligns the complexes with respect to the interface. 

The second equation is the bulk effective resistivity due to particle surface resistivity for a cubic array of mono-dispersed particles with the direction of the electric field aligned with the poles and volume conduction neglected. The constriction resistance is included in the integration of Equations 3.8. These equations are a weak function of the particle geometry. 

Figure 2.106 Energy band diagram of the structure of p -lnP substrate (doped in the 10 cm range) and the homoepitaxial p-lnP film (doped in the low 10 cm" range) showing a back surface field band alignment.

Parallel domain alignment at an interface will propagate into the bulk of a copol5fmer film to a degree dependent on the magnitude of the substrate affinity asymmetry or "surface field" Ay. TEM studies on a PS-b-PMMA lamellar system found a critical thickness (linearly dependent on Ay) below which surface fields are enough to cause the entire film to adopt an L alignment [11]. For example, the critical thickness was 10 lamellar periods when... 

In a thin film, a vertical electric field such as that applied in a parallel-plate capacitor geometry drives a standing alignment of L or Cl microdomains. There is, therefore, a competition between the electric field and the surface fields that favor parallel domain alignment (L or C ). The free energy of Eq. 2.7 is modified in a simple model to include distinct contributions from the surface interactions and the electric field response ... 

Electric field alignment of cylinder-forming PFS-i-PLA copolymer films. (a,c) Surface and cross-sectional SEM images of a cylinder-forming PFS-b-PLA film thermally annealed under a 120 V pm" electric field followed by selective removal of the minority PLA phase. (b,d) Equivalent images of a film annealed with no electric field. 

Ural A, Li YM, Dai HJ. Electric-field-aligned growth of single-walled carbon nanotubes on surfaces. Appl Phys Lett 2002 81 3464-6. 

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