ABSTRACT
The concept of EM waves is attributed to Sir James Clerk Maxwell, who in 1864 published a paper considered to be a crowning achievement of classical physics. There he showed the relation between electric and magnetic elds and concluded that EM waves propagate with the speed of light, indicating that light itself is in the form of an EM wave [Maxwell (1890)]. Even though later studies have shown that quantum mechanics can explain EM energy propagation, still the EM-wave theory explains the light and radiative energy propagation and its interaction with matter at the macroscopic level. The so-called Maxwell equations can explain all the fundamental physics from the nanoworld to stellar systems [Jackson (2005); Mischenko et al. (2006)]. The concepts of reection, refraction, transmission, or, in general, scattering, can be explained with the use of these equations. In addition, these parameters, and emissivity and absorptivity of materials can, in certain cases, be calculated from their optical and electrical properties as shown for the applications discussed in Chapter 3. Below, the relations between radiative, optical, and electrical properties are developed by considering wave propagation in a medium and the interaction between the EM wave and the matter. Physically, an ideal interaction means that the results are for optically smooth, clean surfaces that reect, refract, and transmit the incoming wave. In its most simple case, these interactions assume specular, that is, mirrorlike behavior, as such behavior is mathematically tractable and can be solved using the Maxwell equations. Most real surfaces, however, are not mirrorlike and almost all have surface roughness, contamination, impurities, and crystal-structure imperfections, requiring the development of different approximations to account for diffuse or diffuse-specular reection, refraction, and transmission proles. The departures of real materials from the ideal conditions assumed in the theory are often responsible for large variations of measured property values from theoretical predictions.
