Imaginary refractive index

In order to calculate particle size distributions in the adsorption regime and also to determine the relative effects of wavelength on the extinction cross section and imaginary refractive index of the particles, a series of turbidity meas irements were made on the polystyrene standards using a variable wavelength UV detector. More detailed discussions are presented elsewhere (23) > shown here is a brief summary of some of the major results and conclusions. 

Lindberg, J. D., and J. B. Gillespie, 1977. Relationship between particle size and imaginary refractive index in atmospheric dust, Appl. Opt., 16, 2628-2630. 

A material with an anisotropic, imaginary refractive index ... 

Figure 9.12. Real and imaginary refractive index components of silicon versus wavelength.

Additional functionality that could be incorporated into an instrument is to perform measurements at different wavelengths. The optical size of the particle would thereby change, but the imaginary refractive index would change too, providing access to the imaginary part of the refractive index. 

Figure 8.3 Example imaginary refractive index, k, spectrum of Matrigel (an extracellular matrix).

Like the real refractive index, the imaginary refractive index is also a dimensionless quantity. For pure materials, is given by... 

Figure Bl.26.13. Plot of versus K, the imaginary part of the refractive index.

Imaginary part of complex principal refractive index Birefringence... 

Figure 11. Imaginary part of complex refractive index for polystyrene...

Ellipsometry is used to study film growth on electrode surfaces. It is possible to study films at the partial monolayer level and all the way up to coverage of thicknesses of thousands of angstroms while doing electrochemical measnrements. To get nseful data it is important to determine A and j/ for the bare electrode snrface and the surface with a film. These data are processed to derive the film thickness, d, and the refractive index, h, which consists of a real (n) and imaginary part (k), h = n- ik. So ellipsometry gives information on the thickness and refractive index of snrface hlms. 

From Eq. (3) derive the relations for the real and imaginary parts of the refractive index as Auctions of the permittivity and the electrical conductivity of a given medium. Note drat both n and k are defined as real quantities. 

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