Anisotropic film spectrum

Although the physical thickness of the liquid crystal is only about 15 Angstrom, it is quantum-mechanically resonant at the wavelength of the incident photons due to its slow-wave electronic structure. The spatial profile of the anisotropic absorption spectrum is shown without dimensions. It is dependent on the absorption cross section of the liquid crystalline film. The array factor for this array cannot be determined easily using conventional antenna theory because of its sub-wavelength dimensions and other currently unknown parameters. 

Second, the absorption characteristic of each Rhodonine chromophore is highly directional (15R). This anisotropic absorption is only observed for radiation applied perpendicular to the surface of the film, i.e., parallel to the axis of the Outer Segment. The peak absorption wavelength for resonant absorption by these chromophores is nominally either 342,437, 532 or 625 nm. The chromophore is not polarization sensitive for excitation along this axis. For radiation applied along other axes, such as transverse to the axis of the OS, only the intrinsic absorption characteristic due to conjugate absorption and shared by all retinoids of the Vitamin A Group will be observed. This intrinsic spectrum has a nominal spectral peak at 502 nm at 37C. 

To evaluate photoisomerization and photo-orientation parameters, and should be known, was calculated from the absorption spectrum of the polymer solution before irradiation, assuming the same extinction coefficient in the film and in solution bq was determined by the Fisher s method, modified by Rau, which holds not only for isotropic but also for anisotropic samples when the isotropic absorbance is considered (vide infra). For this determination, the isotropic absorbance change was recorded versus the irradiating light intensity, and the sample absorbance change was extracted for an irradiation flux extrapolated to infinity for three drbierent combinations of irradiation and analysis wavelengths 488-488, 532-488, and 532-532 nm, irradiation and analysis, respectively. These experiments... 

Anisotropic optical properties of free nanopotous anodic alumina films transparent in the visible spectrum for the restrided range of pore diameters and pore intervals are discussed. The basic experimental procedure is presented for the production of these films. Light scattered along pores was experimentally found to have partially a polarization perpendicular to the polarization of the incident light. The results obtained show that the nanoporous structure of anodic alumina films can be purposeful used in LCD to control a light propagation. 

The optical transmission spectra of polycrystalline films are shown in Fig. 1. The spectrum clearly arises primarily from an np ns transition. The peak positions correlate well with the corresponding dissociation transitions in the gas phase. The anisotropy in the solid leads to a small orientation dependence of the peak position in the singlecrystal reflectance spectrum of Na (C222)Na . Recent unpublished work in our laboratory showed that the effect is much larger in Li (C21 l)Cs , which forms extended chains of ceside anions.This orientation dependence is a natural consequence of the removal of excited p-state degeneracy in the anisotropic solid. 

The anisotropy of the line width is clearly manifested. When the external magnetic field is applied parallel to the stretching direction of the film, the signal intensity has a higher intensity in most fi equency regions than that in the case of the field being perpendicular to the direction. The spectra seem to be composed of more than two components. The ENDOR features at low temperatures can be interpreted as the direct evidence of the soliton like spin density by the simulation of the anisotropic spectrum. The maximum frequency of the ENDOR spectrum is related to the spin density, p(0) at the central carbon of the soliton as indicated in Fig. 7.41. 

The observation of a layer of amorphous carbon at the film surface, in combination with the observation of liquid crystal alignment on this surface, suggested the breakthrough idea to replace the polyimide polymer film with an amorphous carbon layer [34]. The essential requirement for liquid crystal alignment (as stated by our model), namely the presence of an anisotropic distribution of directional bonds, can be fulfilled by an ion beam irradiated amorphous carbon layer. This is demonstrated by the presence of the resonance associated with tt orbitals at 285 eV in the absorption spectrum of amorphous carbon (bottom of Fig, 6.12). Its presence indicates that amorphous carbon contains unsaturated sp2 and sp hybridized carbon atoms. While sps hybridization does not lead to any anisotropy, the directional nature of carbon double and triple bonds formed by sp2 and sp hybridized carbon atoms can lead to a breaking of the isotropy of the molecular distribution. It therefore mainly remains the question whether a statistically significant anisotropy in these carbon bonds can be achieved by ion beam irradiation of an amorphous carbon layer. 

Figure 3.27. (a) Simulated s- and p-polarized IRRAS spectra of 10-nm film of anisotropic inorganic material (Table 3.3) at air-water (AW) interface, (b) reflection spectrum of water at >1 = 60°, and (c) ratio a/b. Adapted, by permission, from K. Yamamoto and H. Ishida, Appl. Spectrosc. 48,775 (1994), p. 784, Fig. 12. Copyright 1994 Society for Applied Spectroscopy.

In this section, only the optical constants of isotropic films determined by the multiwavelength approach in IRRAS will be discussed. The optical constants are assumed to be independent of the film thickness, and any gradient in the optical properties of the substrate (Section 3.5) is ignored. This undoubtedly lowers accuracy of the results. Anisotropic optical constants of a film are more closely related to real-world ultrathin films. At this point, it is worth noting that approaches to measuring isotropic and anisotropic optical constants are conceptually identical An anisotropic material shows a completely identical metallic IRRAS spectrum to the isotropic one if the complex refractive index along the z-direction for the anisotropic material is equal to that for the isotropic one [44]. However, to... 

Anisotropic ESR spectroscopy of MbFe/ films provided information about spin state and orientation [20]. In films made from solutions of pH between 6 and 8, myoglobin had an ESR spectrum at 10 K characteristic of native, high-spin heme, suggesting water as an axial ligand of MbFe . Thus, UV-Vis spectroscopy, ESR, and reflectance FT-IR spectroscopy all showed that at medium solution pH values, secondary structures of Mb in these films are similar to native conformations. 

The texture change or memory effect is observed in cholesteric materials with negative dielectric anisotropy [71]. The liquid crystal layer is homogeneously oriented by boundary forces to form the planar texture which is completely transparent if the band of selective light reflection is outside the visible spectrum. The substrates are covered with conducting films that are in contact with the liquid crystal. When a d.c. or low frequency field is applied, the sample is transformed to the so-called focal conic texture. In this texture, the liquid crystal is broken up into small domains which are randomly oriented and have diameters of a few microns. Since these domains are optically anisotropic, they act as scattering centers for visible light. Therefore the focal conic texture exhibits a milky white appearance. 

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