This collection of papers describes investigations of luminescence centers in II-VI crystal phosphors, ruby, and molecular crystals. These investigations were carried out using spectroscopy in a wide range of wavelengths, electron paramagnetic resonance, and polarization methods. The relationship between the thermal and optical depths of electron traps is considered specifically. The articles in this collection should be of interest to all scientists investigating the luminescence of solids.

Inhalt
Investigation of the Spectral-Luminescence Properties of Ruby as Active Laser Medium.- I. Spectral Distribution of Luminescence Quantum Efficiency and Absorption Spectra.- II. Phosphorescence of Ruby. Energy Band Scheme.- III. Color Centers in Ruby.- IV. Effect of an External Electric Field on the Spectrum of Cr3+ in Ruby.- Conclusions.- Literature Cited.- Relationship between Optical Depths of Electron Traps.- §1. Theory of the Method.- §2. Phototransitions and Associated Optical and Thermal Trap Depths.- §3. Apparatus and Measurement Procedure.- §4. Investigated Samples and Excitation Method.- §5. Optical Depths of Traps in ZnS.- §6. Thermal Depths of Traps in ZnS.- §7. Adiabatic and Nonadiabatic Liberation of Electrons from Traps in ZnS.- §8. Optical and Thermal Depths of Traps in Diamond.- §9. Polarons in ZnS.- Literature Cited.- Nonisostructural Paramagnetic Centers in One-Activator Crystal Phosphors.- I. ESR of Mn Ions in ZnS.- II. Cubic and Hexagonal ZnS with Eu2+ Impurity Centers.- III. Influence of Irradiation on Cr3+ Centers in Ruby.- IV. Mn2+ Impurity Ions in the Na2ZnGeO4 Lattice.- Literature Cited.- Application of the Polarization Diagram Method to Studies of Uniaxial Crystals.- §1. Allowance for Birefringence.- §2. Allowance for Absorption of Exciting Light and Luminescence.- §3. Polarization Diagrams of a Rotator.- §4. General Case: Combination of a Linear Oscillator with a Rotator.- §5. Influence of Depolarization.- §6. Analysis of Some Specific Cases.- §7. Experimental Investigation of Zinc Sulfide.- Literature Cited.- Luminescence Polarization Investigation of the Structure of Doped Molecular Crystals.- §1. Structure Investigations of Doped Naphthalene Single Crystals.- §2. Structure Investigations of Crystals with Two Impurities.- §3. Structure Investigations of Doped Anthracene Single Crystals.- §4. Relationship between the Structure of Doped Crystals and Energy Migration between Impurity Molecules.- Literature Cited.- Influence of a Strong Electromagnetic Field on Phase Transitions in Ferroelectrics.- §1. Optically Induced Ferroelectric Transitions.- §2. Heating Effects in a Strong Optical Field.- Conclusion.- Literature Cited.