Optical Properties of Solids

Very broadly speaking, two situations have to be considered in explaining devices such as those we have mentioned. In the first, which is relevant to the ruby laser and to phosphors for fluorescent lights, the light is emitted by an impurity ion in a host lattice. We are concerned here with what is essentially an atomic spectrum modified by the lattice. In the second case, which applies to LEDs and the gallium arsenide laser, the optical properties of the delocalised electrons in the bulk solid are important. 

We shall begin with the first case and take atomic spectra as our starting point. 

An electron that has been excited to a higher energy level will sooner or later return to the ground state. It can do this in several ways. The electron may simply emit a photon 

We shall see now the role played by a similar forbidden transition in the operation of the ruby laser. 

Ruby is corundum (one form of AI2O3) with 0.04 to 0.5% Cr ions as an impurity replacing aluminum ions. The aluminum ions, and hence the chromium ions, occupy 

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D. E. Aspnes. Thin Solid Films. 89, 249, 1982. A detailed review of effective medium theory and its use in studies of optical properties of solids. 

As shown in Fig. 7, a large increase in optical absorption occurs at higher photon energies above the HOMO-LUMO gap where electric dipole transitions become allowed. Transmission spectra taken in this range (see Fig. 7) confirm the similarity of the optical spectra for solid Ceo and Ceo in solution (decalin) [78], as well as a similarity to electron energy loss spectra shown as the inset to this figure. The optical properties of solid Ceo and C70 have been studied over a wide frequency range [78, 79, 80] and yield the complex refractive index n(cj) = n(cj) + and the optical dielectric function... 

Wooten, F., Optical Properties of Solids, Academic Press, San Diego, 1972. 

The optical properties of solid Sg have been studied by ab initio MO calculations of the energy band structure [70] but no experimental data for solid Sg are known. 

Figure 7.8 Optical properties of solid gold spheres of indicated diameters, (a) absorption, (b) scattering. Redrawn from Cortie et a. [118], Copyright (2005) Society of Photo-Optical Instrumentation Engineers.

J. Tauc, in Optical Properties of Solids" (F. Abeles, Ed.), Chap. 5, p. 277. North-Holland, Amsterdam, the Netherlands, 1972. 

Point defects can have a profound effect upon the optical properties of solids. The most important of these in everyday life is color,3 and the transformation of transparent ionic solids into richly colored materials by F centers, described below, provided one of the first demonstrations of the existence of point defects in solids. 

Precipitates have important effects on the mechanical, electronic, and optical properties of solids. Precipitation hardening is an important process used to strengthen metal alloys. In this technique, precipitates are induced to form in the alloy matrix by carefully controlled heat treatment. These precipitates interfere with dislocation movement and have the effect of hardening the alloy significantly. 

Introductory material concerning the magnetic and optical properties of solids is given in ... 

Weber, M. 1., Handbook of Optical Materials, CRC Press, Boca Raton, Florida (2003). Wooten, R, Optical Properties of Solids, Academic Press, New York (1972). 

Spicer, W. E., in Optical Properties of Solids (F. Abeles, ed.). North-Holland Publ.,... 

Abeles, F. Optical properties of solids. Amsterdam North Holland Publish. Co. 1972. Bradley, C. J., Cracknell, A. P. Mathematical theory of symmetry in solids Representation theory for point groups and space groups. Oxford Qarendon Press 1972. Becher, H. J. Angew. Chem. Intern. Ed. Engl. 77 26 (1972). 

Toll (1956) examines the logical foundations of causality and the dispersion relations. Goldberger (1960) begins his article with a good historical survey another discussion within the context of high-energy physics is by Scadron (1979, pp. 326-329), whereas optical properties of solids form the backdrop for Stern s (1963) discussion. And an entire book by Nussenzveig (1972) is devoted to dispersion relations. 

Optical properties of solids encompasses a field of study too extensive to be covered adequately in a single volume. Monographs that emphasize different aspects of the subject, together with the topics they treat especially well, are listed below. 

Dixon, J. R., 1969. Electric-susceptibility mass of free carriers in semiconductors, in Optical Properties of Solids, S. Nudelman and S. S. Mitra (Eds.), Plenum, New York, pp. 61-83. 

Stern, F., 1963. Elementary theory of the optical properties of solids, Solid State Phys., 15, 299-408. 

Tauc, J. (Ed.), 1966. The Optical Properties of Solids, Academic, New York. 

Hamakawa, Y. and Nishino, T. "Optical Properties of Solids New Developments," ed. Seraphin, B.O. (North-Holland, Amsterdam 1976) P. 225. 

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