Maxwell-Garnett effective medium approximation

The TEM data have been used to simulate, in the frame of the Mie theory and Maxwell-Garnett effective medium approximation [15], the optical absorption spectra of the sample implanted with 5 x lO Au /cm. The results are reported in Figure 8(c). In the first model used to describe... 

This possibility is extremely useful for the structural characterization of polymer blends. The optical properties of the polymer layer can be described by a so-caUed effective dielectric function, which is a suitable average of the dielectric functions of the two components. Three averaging effective medium approximation (EMA)s -the linear, Maxwell-Garnett and Bruggeman EMAs - are widely used for this purpose [9]. These approximations differ in their spectral densities for a given volume fraction. 

The main issue in the effective-medium approximations is to relate the polarizability a. to the relative permittivity r, where = i/ s, and E[ is the relative permittivity of the inclusion. For spherical particles and at frequencies for which the inclusions can be considered very small, the Maxwell-Garnett formula uses the relation... 

Figure 7.2. Random units 1 and 2 in the effective medium (symmetrized Maxwell Garnett approximation).

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