1 Introduction.- 2 Phonon Spectra of Solids: Indicator of Their Isotope Purity.- 2.1 Theory of Lattice Dynamics.- 2.2 Elastic Properties.- 2.2.1 Theoretical Background of Elastic Constant Measurements.- 2.2.2 Experimental Results and Interpretation.- 2.3 Vibrational Properties.- 2.3.1 Phonon Dispersion and Density of Phonon States.- 2.3.2 Low Concentrations: Localized, Resonant, and Gap Modes.- 2.3.3 Phonon Spectra of Isotopically Mixed Crystals.- 2.3.4 Isotopically Induced Disorder Effects in Vibrational Spectra.- 3 Thermal Properties.- 3.1 Dependence of the Thermal Conductivity on the Isotopic Composition.- 3.1.1 Theoretical Models.- 3.1.2 Experimental Results.- 3.1.3 High Thermal Conductivity Silicon.- 3.2 Lattice Constant Dependence on Temperature and Isotopic Composition.- 4 Isotopic Renormalization of the Electronic Excitation Energy Spectrum.- 4.1 Exciton States.- 4.2 Exciton-Phonon Interaction.- 4.3 Giant Isotopic Effect in the Energy Spectrum of Wannier-Mott Exciton in LiH Crystals.- 4.4 Nonlinear Dependence of Band-Gap Energy on the Isotopic Effect.- 4.5 Renormalization of Binding Energy of Wannier-Mott Excitons by Isotopic Effect.- 4.6 Nonlinear Dependence of Binding Energy on Isotopic Concentration.- 4.7 Isotopic Effect in the Luminescence Spectrum.- 5 Process of Self-Diffusion in Isotopically Pure Materials and Heterostructures.- 5.1 General Remarks.- 5.2 The Relation of Diffusion Experiments to the Mathematics of Diffusion.- 5.3 The Self-Diffusion Process.- 5.4 The SIMS-Technique.- 5.5 Self-Diffusion of Li and H in LiH Crystals.- 5.6 Self-Diffusion in Intrinsic Ge.- 5.7 Self- and Interdiffusion of Ga and Al in Isotopically Pure and Doped Heterostructures.- 6 Neutron Transmutative Doping.- 6.1 The NTD Process: A New Reactor Technology.- 6.2 Reactor Facilities for Transmutative Doping.- 6.3 Nuclear Reaction Under the Influence of Charged Particles.- 6.4 Nuclear Reaction Under the Action of the ?-Rays.- 6.5 Nuclear Reactions Under the Influence of Neutrons.- 6.6 The Influence of Dopants.- 6.7 Atomic Displacement Effects in NTD.- 6.8 Experimental Results.- 6.8.1 Ge.- 6.8.2 Silicon.- 6.8.3 Other Compounds.- 7 Optical Fiber.- 7.1 Optical Communication.- 7.2 Maxwell’s Equations.- 7.2.1 Planar Geometry.- 7.2.2 Cylindrical Geometry.- 7.2.3 The Electromagnetic Wave Equation.- 7.3 Geometric Optics of Fibers.- 7.4 Waveguide Mode Propagation.- 7.5 Pulse Spreading.- 7.6 Materials for Optical Fibers.- 7.6.1 Absorptive Losses in Glasses.- 7.6.2 Rayleigh Scattering.- 7.7 Fiber Preparation.- 7.8 Isotopes in Fibers.- 8 Laser Materials.- 8.1 Some General Remarks.- 8.2 Absorption and Induced Emission.- 8.3 Semiconductor Lasers.- 8.3.1 Heterojunction La.- 8.3.2 Study of Excitons Lasing.- 8.4 Nonlinear Properties of Excitons in Isotopically Mixed Crystals.- 9 Other Unexplored Applications of Isotopic Engineering.- 9.1 Isotopic Information Storage.- 9.2 Isotopic Structuring for Fundamental Studies.- 9.3 Other Possibilities.- 10 Conclusion.- References.
