Electron microscope refractive index

Microscopy. This is a powerful tool for studying visually the distribution of the two phases in the polyblend. One can tell not only the domain size of the dispersed phase but also which polymer forms the dispersed phase from refractive index. A phase contrast light microscope can detect heterogeneity at the 0.2-10 /x level. If the sample can be stained preferentially and sectioned with microtome, then under favorable conditions electron microscopy can show heterogeneity to a very fine scale. In a study of PVC-poly(butadiene-co-acrylonitrile) blend,... 

Inclusions of the order of 2 nm diameter or larger can also be made visible by a phase contrast mechanism. When a crystal is oriented so that no strong, low-order diffracted beeuns are operating, all the Fourier coefficients Kg of the potential are negligibly small except the mean inner potential Kq, which is effectively the refractive index of the crystal for electrons (as explained in Sections 4.1 and 4.2). If the mean inner potential 0i of an inclusion is different from the mean inner potential Kq of the matrix, then the inclusion can be considered as a phase object. In the light microscope, a phase object is usually barely visible at exact focus but if the objective lens is slightly defocused, it will be seen with high contrast. 

The electron density equation very simple structures such as NaCl can be solved by comparison of the relative intensities of the diffraction spots. For more complicated structures, the power of Fourier transform methods was soon appreciated [27]. In order to produce an image of the structure, the diffracted rays must be combined. In the light microscope this is achieved by the focussing power of the objective lens (Fig. 3b). For X-rays the refractive index of almost all substances is close to 1 and it is not possible to construct a lens. The diffracted rays must be combined mathematically. This is achieved with the electron density equation. 

On the other hand, for obtaining the multilayers of required optical properties, the exact variation of etching rate and porosity (or refractive indices) as a function of current density is needed (an example adapted from the reference (Frohnhoff et al. 1995) is provided as Fig. 2). Although multilayer structures may require thin layers, the error in porosity measurements for thin layers <200 nm makes it unreliable. Hence, the thickness and refractive index (or approximate porosity) of relatively thick monolayers are generally extracted from scanning electron microscope and normal reflectance spectra/spectroscopic ellipsometty, respectively. Apart from that several other remarks can be made ... 

All measurements are performed using the refractive index of CdS. In the case of cadmium sulfide nanoparticles produced in the w/o microemulsion the viscosity rj and the refractive index no of the continuous oil phase, namely the xylene-pentanol (1 1) mixture ( = 1.454 cP, D = 1165) are used. Consequently rj and no for water are used when the CdS nanoparticles are redispersed in the aqueous phase. Morphology and size of the redispersed CdS particles are also determined by transmission electron microscopy. Therefore, a small amount of the aqueous solutions is dropped on copper grids, dried and examined in the EM 902 transmission electron microscope (Zeiss) (acceleration voltage 90 kV). The high amount of surfactant brings also difficulties for the preparation of the samples for TEM measurements and consequently samples have to be washed with water to reduce the amount of surfactant. 

Table 1 Averaged fitting results obtained for the structure parameters along the OC segment of the isotherms. Distance between nearest neighbours, D, particle diameter, d, surface coverage, y, immersion depth, k, all from the gradient-layer model. Effective refractive index, efr, diameter, Jhom both from the uniform-layer method. Diameter obtained from the transmission electron microscope images, 5 tem ...

For simple liquids it is straightforward to relate a bulk macroscopic property to its microscopic origins. Consider, for example, how the molecular electronic polarizability a manifests itself in the refractive index n of a simple liquid. The relative permittivity (the dielectric constant) is a simple function of a and the number density Nof molecules (the number per unit volume) in the liquid ... 

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