Publisher Summary This chapter describes elementary theory of the optical properties of solids. One of the most powerful tools for studying the properties of solids is the measurement and analysis of their optical properties. Some of the results required for such an analysis are described in the chapter with emphasis on the detailed development of simple models. It expresses many of the results in numerical form and has dictated the use of meter–kilogram–second (mks) units throughout. The treatment is elementary in the sense that no physics beyond Maxwell's equations and simple quantum mechanics is used in the chapter. Dispersion relations as applied to the analysis of optical properties are discussed in the chapter. It summarizes some of the classical results for two very important physical systems, the free-electron gas and the optical lattice vibrations in ionic crystals. These systems are sufficiently simple that detailed results can be obtained very easily, yet realistic enough that the results give quite a good representation of at least some of the properties of real solids.

Optical Properties of the Alkali Metals

Elementary Theory of the Optical Properties of Solids

Measurements have been made of the characteristic electron energy loss spectra of beryllium, antimony, bismuth, germanium, tin, cadmium, copper, platinum, lead and calcium using the reflection technique and with 750 eV and 1500 eV primary electrons. The spectra of each element were found to consist almost entirely of combinations of two fundamental energy losses which were identified as plasma and lowered plasma losses. A striking correlation between the lowered plasma losses and the corresponding calculated values of hωp/radical2 was observed (ωp is the plasma frequency), and it is suggested that the magnitude of the lowered plasma loss may be useful as an indication of the effective free electron density. If the specimen oxidized appreciably, the intensity of the lowered plasma loss decreased rapidly and a new modified lowered plasma loss appeared. It is considered that the present results are characteristic of clean metal surfaces and that many of the discrepancies in past work can be explained by the presence of surface contaminants.

https://iopscience.iop.org/article/10.1088/0370-1328/76/5/301/pdf

The Origin of the Characteristic Electron Energy Losses in Ten Elements

Measurements have been made on evaporated thin films of Al, Sn, In, Bi, Au, Ag, and Cd in order to correlate optical transmission, reflection, and photoemission in the far ultraviolet. Thin unbacked films prepared outside the spectrograph and glass-backed films prepared inside the spectrograph were used. The frequency at which the films change from a reflecting medium to a transmitting medium has been compared with the plasma frequency predicted by Bohm and Pines and also with electron energy eigenlosses in metals observed by Marton et al. Some new absorption transitions have been observed and related to x-ray absorption edges. A qualitative correlation between the photoelectric yields and corresponding optical properties has been attempted.

Optical and photoelectric properties of thin metallic films in the vacuum ultraviolet

Thermal and optical effective masses are defined and expressions for them obtained for metals with arbitrary Fermi surfaces. The ratio of these two effective masses is shown to depend on the shape of the Fermi surface. It follows from experimental values of the optical constants and the electronic heat capacity that the Fermi surface is not spherical in Cu, Ag and Au and that it contacts the surface of the first Brillouin zone to an appreciable degree in Cu and Ag. Similar evidence indicates a non-spherical Fermi surface in Li, Na and K. A simplification of the theory of the optical constants of metals is given which fits the experimental data for Na, K, Rb and Cs satisfactorily. Values of the plasma frequencies and widths of the plasma resonances of the alkali metals are calculated.

Optical constants, heat capacity and the fermi surface

The effects of optical illumination and impurities on colloid formation are studied in additively coloured KCl and in NaBr coloured by ultra-violet light. It is shown that at elevated temperatures additively coloured KCl behaves as an auto-sensitized photographic system. A theory of the colloid band is presented which takes account of ion core polarization and harmonic mean effective mass for arbitrary ellipsoidal particles. The colloid band is identified as a bounded plasma resonance, shifted into the visible region by the boundary conditions. Plasma frequencies computed from the positions of the colloid bands are in good agreement with other estimates. The spectral dependence of photoconductivity associated with the colloid band is related to the band structure of the host medium.

https://iopscience.iop.org/article/10.1088/0370-1328/75/5/303/pdf

Optical Properties of the Alkali Metals

Citations

Elementary Theory of the Optical Properties of Solids

The Origin of the Characteristic Electron Energy Losses in Ten Elements

Optical and photoelectric properties of thin metallic films in the vacuum ultraviolet

Optical constants, heat capacity and the fermi surface

Coagulation, Optical Absorption and Photoconductivity of Colloid Centres in Alkali Halides

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