Isotropic film

It is important to note that comparable information to that obtained from infra-red spectroscopy can in principle be obtained from refractive index measurements. It has been shown that for a transversely isotropic film, the relationship equivalent to 11(c) is... 

Chiral Isotropic Film Achiral Isotropic Film... 

It is important to note that the coefficients fp, gp, and hs are always nonvanishing, for both achiral and chiral isotropic films. On the other hand, fs, gs, and hp can only be nonvanishing if the isotropic film is chiral (nonracemic) because they completely depend on the chiral susceptibility components. Note that gs is always equal to zero within the electric dipole approximation. The sign of the chiral expansion coefficients changes between enantiomers, while that of the achiral expansion coefficients stays the same. Experimental determination of all expansion coefficients fully characterizes the nonlinearity and nonlinear optical activity of the sample. Once all expansion coefficients are... 

The symmetry of the LB films was determined by polarized ultraviolet-visible (UV-Vis) absorption spectroscopy, optical rotation, and second-harmonic generation. All studies showed that the constructed LB films are anisotropic in the plane of the film and that the symmetry of the film is C2 with the twofold rotation axis perpendicular to the film plane. For example, when the SH intensity is plotted as a function of the azimuthal rotation angle (rotation around an axis perpendicular to the plane of the film), the twofold symmetry becomes evident (Figure 9.23). Isotropic films generate an SH signal independent of the azimuthal rotation angle. On the other hand, the LB... 

The fragments of macromolecules with ordered cholesterol group sequences, that are formed in bad solvents, may serve as nuclei of supermolecular order in films, obtained from these solvents. Structural and optical studies have shown that PChMA-11 films produced by solvent evaporation display different properties those obtained from chloroform and toluene solutions (small relaxation times, see Table 17) are optically isotropic, and those obtained from heptane solutions (large relaxation times, see Table 17) are optically anisotropic, what reflects the differences in conformational state of polymeric chains in these films. Contrary to the optically isotropic films, a high degree of side branch ordering characterizes optically anisotropic films, which is confirmed by X-ray studies. The observed difference of LC polymer structure in the bulk is thus the consequence of their different conformational state in solution this reveals some possibilities for the control of LC polymer structure at the initial steps of mesophase nucleation in solutions. 

Fig.7 FT-RAIRS spectrum of Rh2C04Cl2 on Ti02(l 10) [56], Measurements are carried out at (p=83 , and can be compared directly with the predictions of the model used for an isotropic film on an isotropic, non-absorbing substrate (Fig.6). The lines indicate the expectation values for the modes in the condensed phase.

For an isotropic film, the displacement components can be considered independent of each other, while calculating the surface mechanical impedance (Z). Therefore, the surface mechanical impedance associated with each displacement component M is given by... 

Note (a). Biaxial oriented film. (b). isotropic film. (c). Value measured in the parallel orientation, (d). Value measured in the perpendicular orientation. 

Tensile stress a MPa Isotropic film Oriented film Fibers 25-62 1,800 3,000 (1, 4, 8,10)... 

In this section, we list the exact formulas of Hansen [99] and Abeles [125] for isotropic films and the thin-fihn approximation of Yamamoto and Ishida [126] for the calculation of dansmission spectra of anisotropic ultrathin films on planar isotropic supports. The spectral features and dependences predicted by these formulas are discussed in Sections 2.1 and 3.3.4. 

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... 

Films can be divided into three classes—isonopic, uniaxial, and biaxial—depending on the form of their permittivity tensor s (1.1.2°). For isotropic films, the three principal values of the permittivity tensor are equal, i = 62 = s-, and there is no preferred orientation within the film. The permittivity tensor of a uniaxial film has two different principal values, one that describes the propagation of radiation in the film plane and another that is perpendicular to the film plane, so that = Sy s. For a biaxial film all of the principal values of the permittivity tensor are different, so that Ex By For crystalline films with triclinic... 

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