Optical Magnitudes and the Dielectric Constant

Our first task is to connect measurable optical magnitudes with the dielectric constant, which describes the response of a given material to an applied electric field. This 

An Introduction to the Optical Spectroscopy of Inorganic Solids J. Garda Sold, L. E. Bausa, and D. Jaque 2005 John Wiley Sons, Ltd ISBNs 0-470-86885-6 (HB) 0-470-86886-4 (PB) 

The real part of this nnmber is the normal refractive index n = c/v(c and v being the speed of light in vacnnm and in the medium, respectively). The imaginary part of the complex refractive index, k, is called the extinction coefficient. It is necessary to recall here that both magnitndes, n and k, are dependent on the frequency (wavelength) of the propagating wave co,N = N(co). 

Taking into account Eqnation (4.2) and that k = co/c. Equation (4.1) can be rewritten as 

Let us now relate the refractive index and the extinction coefficient with the relative dielectric constant of the solid material. Assuming a nonmagnetic solid (relative 

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