ABSTRACT
This chapter presents a detailed exposition of the radiation properties of surfaces. The magnitude, the angular distribution, and the wavelength dependence of the radiation properties are all very sensitive to the condition of the surface. Surface condition includes such factors as roughness, oxide layers, and physical and chemical contamination. The qualitative description of a surface by terms such as smooth, polished, rough, and oxidized is generally insufficient to permit an accurate specification of the radiation properties. The qualitative variation of the monochromatic properties with wavelength is fairly well-established. The dependence of the monochromatic properties on temperature may be discussed. In the case of metals, the monochromatic emittance increases with increasing electrical resistance and, correspondingly, with increasing temperature. In the far infrared, according to electromagnetic theory ∈λ varies as the square root of the electrical resistivity. The effect of surface roughness on the monochromatic reflectance distribution has also been investigated analytically by the application of electromagnetic theory.
