These proceedings report the lectures and seminars of a course entitled "Luminescence of Inorganic Solids," held at Erice, Italy, June 15-30, 1977. This course \'7aS an activity of the International School of Atomic and No1ecu1ar Spectroscopy of the "Ettore Hajorana" Centre for Scientific Culture. The course opened with an overvievl of the present status of luminescence research and with an assessment of its future trends. The following lectures introduced the basic formalism behind the interaction of matter with the radiation field and the lattice phonons. The luminescence properties of various classes of in- organic materials were treated next, for the specific cases of unfilled-shell activators (transition metal, lanthanide and actinide ions) and filled-s~e11 activators (s2 and d10 ions). Different models suitable for the description of the luminescence properties of semiconductors vlere examined next. The dynamics of energy transfer and relaxation in the excited state of t;1e activators were treated in lectures devoted to the luminescence phenomena of sensitization, concentration quenching and thermal quenching. Finally, the relevance of luminescence studies to the field of phosphor technology and to the laser field Has examined. Each lecturer began the treatment of this topic(s) at a fundamental level and finally reached the current level of research. The sequence of the lectures was determined by the requirements of a didactical presentation. The emphasis of the course was primarily on basic principles. The formal lectures Here complemented by seminars and discussions.

Table of Contents:
Overview and Trends of Luminescent Research.- Abstract.- I. Introduction.- II. General Characteristics of Current Research.- III. Representative Selected Basic Research.- III.A. Configuration Coordinate Model for Luminescence and "Hot" Luminescence.- III.B. Electron-Hole Condensation.- III.C. Complex Luminescent Associates.- IV. Selected Applied Research.- IV.A. Ordered Inorganic Luminescent Solids.- IV.B. Structural Luminescent Materials.- IV.C. Electroluminescence.- V. Conclusions.- Acknowledgment.- References.- Interaction of Radiation with Ions in Solids.- Abstract.- I. Introduction.- II. Quantum Theory of a Solid.- II.A. The Hamiltonian.- II.B. The Meaning of the Adiabatic Approximation.- II.C. The Adiabatic Approximation and the Role of Symmetry.- III. Photons and the Radiation Field.- III.A. The Classical Radiation Field.- III.B. Solutions of the Field Equation.- III.C. Periodic Boundary Conditions.- III.D. The Hamiltonian of the Radiation Field.- III.E. The Quantization of the Radiation Field.- III.F. Energy Levels and Eigenfunctions of Abstract Radiation Field.- III.G. The Operator Vector Potential.- IV. Interaction of Radiation with Charged Particles.- IV.A. The Hamiltonian of a Charged Particle in an Electromagnetic Field.- IV.B. The Interaction of a Charged Particle with Abstract Radiation Field.- IV.C. First Order Processes.- V. Absorption and Emission Processes.- V.A. Transition Probabilities for Absorption and Emission.- V.B. "Upward" and "Downward" Induced Transitions.- V.C. About Spontaneous Emission.- VI. Radiative Processes of Ions in Solids.- VI.A. Statement of the Problem.- VLB. Interaction of Radiation with Molecular Complexes. Franck-Condon Principle.- VI.C. Generalization of the Franck-Condon Approximation.- VI.D. Summary of Radiative and Non-radiative Processes in Solids.- References.- Multiphonon Interaction of Excited Luminescent Centers in the Weak Coupling Limit: Non Radiative Decay and Multiphonon Side Bands.- Abstract.- I. Introduction.- II. Some Experimental Facts About Different Multiphonon Processes.- II.A. Multiphonon Non Radiative Decay.- II.B. Multiphonon Assisted Energy Transfer.- II.C. Multiphonon Side-Bands Excitation.- II.D. Multiphonon Absorption of Pure Solids.- III. Non Radiative Decay. Theoretical Aspects.- III.A. The Nth Order Methods.- 1. The Nth Order Time Dependent Perturbation Method.- 2. The Nth Order Crystal Field Method.- 3. The Exponential Energy Gap Law.- 4. The Temperature Dependence.- III.B. The Non-Adiabatic Hamiltonian Method.- 1. Usual Approximation.- 2. Expression for the Non Adiabatic Hamiltonian in the Adiabatic Approximation.- 3. Transition Probability Calculations.- 4. Discussion of the Preceding Results.- 5. The Temperature Dependence.- IV. Multiphonon Side-Bands.- IV.A. Theoretical Treatment and Formal Analogy with Non Radiative Decay.- IV.B. The "Pekarian" Function and the Energy Gap Law.- IV.C. Relation Between Multiphonon Side-Bands in Absorption or Emission and Anti-Stokes and Stokes Multiphonon Excitation.- V. Experimental Results for Multiphonon Excitation in Ln3+Ions and Comparison with Non Radiative Decay.- V.A.Experimental Set-up and Results for Excitation in Different Matrices.- 1. The Experimental Set-up.- 2. Relation Between Fluorescence Intensity and Excitation Probabilities.- 3. Some Results.- V.B.Comparison of the Experimental Exponential Gap Law for Excitation and for Non Radiative Decay.- 1. Values for Parameters ? and ?s.- 2. Electron-Phonon Coupling Parameter Values.- 3. Mediating Phonon Frequency and Cut-off Phonon Frequency.- V.C.Application to the Prediction of Ln3+ Doped Phosphors Properties.- VI. Conclusion.- References.- Energy Levels and Transitions of Transition Metal Ions in Solids.- Abstract.- I. Introduction.- II. Properties of the Host Material.- III. Electronic States of the Transition Metal Ions.- IV. Radiative Transition Probabilities.- V. Radiative and Non Radiative Transitions on Transition Metal Ions in Solids.- VI. Effect of Changing Crystalline Environment on the Optical Properties of the Transition Metal Ion.- VII. The Ion-Lattice Interaction References.- Experimental Spectroscopic Techniques for Transition Metal Ions in Solids.- Abstract.- I. Introduction.- II. Determination of Energy Levels.- III. The Effect of Site Symmetry on the Optical Spectrum of the Ion.- IV. Overlapping Luminescence Transitions.- V. The MgO:Cr3+System: An Example Acknowledgment.- References.- Luminescence from Solids with High Concentrations of Transition Metal Ions.- Abstract.- I. Introduction.- II. Exchange-Coupled Ion Pairs.- III. Fully Concentrated Materials.- IV. Luminescence from Fully Concentrated Materials.- References.- Spectroscopy and Luminescence of Lanthanides and Actinides.- Abstract.- I. Introduction.- II. Outline of Discussion.- III. The 4f2Configuration Spectra and Basic Interactions.- IV. Tensor Operators in Atomic Spectroscopy.- V. Many-Electrons Configurations.- V.A. The Case for Additional Quantum Numbers.- V.B. Seniority, Coefficients of Fractional Parentage and Unit Tensor Operators.- V.C. Intra-atomic Magnetic Interactions.- VI. Rare-Earth Electronic Levels in the Condensed State.- VII. Intensity of Radiative Transitions in Lanthanide Ions.- VIII. Systematics in Rare-Earth Spectra.- VIII.A. Solution Spectra.- 1. The Cloud-Expanding (Nephelauxetic) Effect.- 2. Hypersensitive Transitions.- VIII.B. Absorption and Emission Spectra in LaCl3.- 1. Selection Rules.- 2. The Time Reversal Operator and Additional Selection Rules.- 3. Zeeman Effect.- 4. Crystal-Field Parameters for LaCl3.- VIII.C. An Example of Analysis of RE Spectra.- VIII.D. Technological Applications of RE Luminescence.- IX. Solution and Solid State Spectroscopy of Actinides.- IX.A. Introduction.- IX.B. The Oxidation States of 5f Ions.- IX.C. Spectroscopic Techniques.- IX.D. Spectra of Trivalent Actinides.- 1. Solution Spectra.- 2. The Question of the Crystal Field Strength in the Actinides.- 3. Crystal Spectra.- 4. Comparison of Lanthanides and Actinides.- IX.E. Dye Laser Excited Emission from Short Lived Isotopes.- Acknowledgment.- References.- Luminescence Spectra of Solids: Filled-Shell Ions.- Abstract.- I. Introduction.- II. Atomic Spectroscopy of Closed-Shell Ions.- II.A. Quantum-Mechanical Postulates.- II.B. One-Electron System.- II.C. Many-Electron System.- 1. Slater Determinants.- 2. Electron Configuration.- 3. Terms and States.- II.D. Excited Configurations of ns2-Type Ions.- 1. ns np Configuration.- 2. np2Configuration.- II.E. Excited Configurations of nd10-Type Ions.- 1. nd9n's Configuration.- 2. nd9n'p Configuration.- III. Closed-Shell Ion Spectroscopy in Crystals.- III.A. General Formalism.- 1. Symmetry Considerations.- 2. Molecular Orbital Method.- 3. Total Energies.- 4. Orbital Energies.- 5. Transition Energies.- III.B. ns2-Type Ions.- 1. Cubic Environment.- 2. Lower-Symmetry Environment.- III.C. nd10-Type Ions.- 1. Cubic Environment.- 2. "Off-Center" Positions.- Acknowledgment.- References.- Generalized Excitations in Pure Ionic Crystals.- Abstract.- I. Introduction.- II. Quantum-Mechanical Resonance.- III. Generalized Excitations in Crystals.- III.A. Setting of the Problem.- III.B. Eigenfunctions.- III.C. Dispersion Relations for Generalized Excitations.- III.D. Effective-Mass Treatment.- III.E. Generalization to Three Dimensions.- III.F. Interactions Involving Generalized Excitations.- 1. Generalons and Photons.- 2. Generalons and Phonons.- 3. Generalon-Generalon Interactions.- IV. Phonons as Generalons.- V. Excitons.- V.A. General Considerations.- V.B. Dispersion Relations.- V.C. General Properties of the Transfer Matrix Element.- V.D. Davydov Splitting.- V.E. Optical Creation of Excitons.- V.F. Exciton-Phonon Interactions.- 1. Form of the Interaction.- 2. Line Broadening.- 3. Indirect Transitions.- 4. Self-Trapping.- VI. Magnons.- VI.A. Setting of the Problem.- VI.B. Dispersion Relations.- VI.C. The Exciton-Magnon Interaction.- 1. Form of the Interaction.- 2. Basic Properties of the Interaction.- Acknowledgment.- References.- Luminescent Processes in Semiconductors.- Abstract.- I. The Usual Semiconductors and Phosphors; Their Gaps.- I.A. Homopolar and III-V Semiconducting Phosphors.- I.B. Amorphous Semiconductors.- I.C. II-VI Compounds.- I.D. Mercury Calcogenides.- II. Near Bandgap Transitions.- II.A. Absorption Leading to Free Carriers.- 1. The Case of Direct Transitions.- 2. The Case of Indirect Transitions.- II.B. Electron-Hole Interaction, Excitons.- 1. Excitons.- 2. The Corrections to the Absorption Curve.- 3. The "Urbach's Tail".- II.C. Luminescence Processes Involving Free Carriers or Free Excitons.- 1. Luminescent Emission Abvoe the Band Gap.- 2. The Free Exciton Emission from Pure Germanium.- 3. The Shape of the Free Exciton Lines in CdS.- II.D. Free Excitons versus Bound Excitons.- II.E. Excitonic Molecules and Electron-Hole Drops.- 1. Excitonic Molecules.- 2. Electron-Hole Drops.- III. Transitions Involving Localized Levels.- III.A. Hydrogen-Like Levels.- 1. Hydrogen-Like Donors and Acceptors.- 2. Infrared Transitions Involving the Excited States.- 3. "Free to Bound" Transitions.- III.B. Isoelectronic Traps.- III.C. Donor-Acceptor Pairs Emission.- III.D. An Example of a Transition Element in Semiconductors: Mn++.- References.- Energy Levels of Strongly Interacting Ion Pairs.- Abstract.- I. Introduction.- II. Interaction Processes.- II.A. Magnetic Dipolar and Electric Multipolar Interactions.- II.B. Direct Exchange and Superexchange.- III. Interaction Processes for Rare-Earth Ions.- III.A. Effective Spin Hamiltonian and Energy Levels for Interacting Kramers' Doublets.- III.B. Case of Nd3+Pairs.- III.C. Brief Review of Interaction Processes for Other Rare Earths.- IV. Interaction Processes for Iron-Group Ion Pairs.- IV.A. Exchange Hamiltonians and Energy Levels.- IV.B. Case of Cr3+Pairs.- 1. Fundamental States.- 2. Excited States.- IV.C. Other Iron-Group Ion Pairs.- V. Concluding Remarks.- References.- Polaron Theory Applied to Luminescent Point and Associated Impurities.- Abstract.- I. Introduction.- II. The Static Approximation.- III. Franck-Condon Principle for Defects and Large Orbits.- IV. Nonadiabatic Defects.- V. Application of the Theory to Some Adiabatic and Some Non-Adiabatic Systems.- Acknowledgments.- References.- On the Theory of the Effects of Hydrostatic Pressure on the Optical Spectra of Impurities in Solids.- Abstract.- I. Introduction.- II. Pressure Dependence of Impurity Spectra in the Harmonic Approximation.- III. The Effects of Anharmonicity on the Pressure Dependence of Impurity Spectra.- IV. Critiques of Other Theoretical Analyses.- V. Conclusions.- Acknowledgments.- References.- Pressure-Dependence of the Probability of Vibronic Transitions.- Abstract.- I. Introduction.- II. General Analysis for Vibronic Transitions.- III. Specific Vibronic Transitions.- IV. Conclusions.- Acknowledgment.- Materials Science of the Luminescence of Inorganic Solids.- Abstract.- I. Introduction.- II. Spectral Position of Absorption and Emission Bands.- II.A. The Eu3+Ion (4f6).- II:B. The Eu2+Ion (4f7).- II.C. The Niobate Octahedron (Nb5+(02-)6).- II.D. The Pr3+Ion (4f2).- III. The Quantum Efficiency of Isolated Luminescent Centers.- III.A. General.- III.B. Trivalent Rare-Earth Ions (Transitions Within the 4fnConfiguration).- III.C. The Eu3+Ion (4f6) and Its Charge-Transfer State.- III.D. The Ce3+Ion (4f1).- IV. Concentration Quenching of Luminescence.- IV.A. Energy Transfer.- IV.B. Concentration Quenching.- V. Sensitized Luminescence.- VI. Rules to Predict Efficient Phosphors.- VIII.Applications.- VIII.A. The Eu3+ Ion.- VIII.B. The Eu2+ Ion.- References.- Resonant Secondary Emission of Impurity Centres in Crystals: Luminescence, Hot Luminescence, Light Scattering.- Abstract.- I. Introduction.- II. Absorption-Luminescence as a Two-Photon Three Step Process.- III. Resonant Secondary Emission Formula for a Useful Model.- IV. Concluding Remarks.- References.- Topical Problems of Laser Crystal Physics.- Abstract.- I. Introduction.- II. On the Nature of the Concentration Quenching of Luminescence of Nd3+ in Crystals.- III. Garnet-RE Laser Crystals.- IV. Extension of Generation Wavelength Range in Crystal Lasers.- V. Conclusion.- References.- Applications of Luminescence.- Abstract.- I. Introduction.- II. Fluorescent Lamp Phosphors.- III. Cathode Ray Tube Phosphors.- IV. Electroluminescence.- V. X-Ray Screens and Detectors.- VI. Miscellaneous Applications and Summary.- Acknowledgments.- References.- Modern Techniques in Optical Spectroscopy.- Abstract.- I. Survey of Laser Spectroscopy Techniques.- I.A. Laser Spectroscopy.- I.B. Ultra-High Resolution Spectroscopy.- I.C. Non-Linear Spectroscopy.- I.D. Ultra-Fast Time Spectroscopy.- I.E. Coherent Transient Effects.- I.F. Summary.- II. Site Selection Spectroscopy Investigations of Energy Migration Among Ions in Solids.- II.A. Summary of Conventional Spectroscopy Results.- II.B. Fluorescence Line Narrowing Studies.- II.C. Experimental Results for Glass Hosts.- II.D. Experimental Results for Crystalline Hosts.- II.E. Theoretical Considerations.- III. Techniques for Directly Measuring Radiationless Transitions.- III.A. Review of Standard Methods of Investigating Radiationless Decay Processes.- III.B. Photoacoustic Spectroscopy (PAS)-Microphone Detection.- III.C. PAS-Transducer Detection.- III.D. Calorimetric Techniques.- III.E. Summary.- References.- Long Seminars.- Fluorescence Studies of Concentrated Mn2+ Systems.- Abstract.- I. Introduction.- II. Optical Properties of MnF2.- III. Optical Properties of RbMnF3.- IV. Fluorescence Studies of KMnF3.- IV.A. Experimental Details.- IV.B. Experimental Results.- IV.C. Interpretation and Model.- Acknowledgments.- References.- Luminescence Properties of Rare Gas Solids. I. Emission Bands and Excitation Spectra.- Abstract.- I. Introduction.- II. Emission Bands of Pure Rare Gas Solids.- II.A. The Main Luminescence Bands of Xe, Kr, Ar (OL).- II.B. Luminescence of Solid Ne.- II.C. Hot Luminescence and Narrow-Line Luminescence.- III. The Luminescence Centres and Explanation of the Luminescence Spectra.- III.A. Formation and Properties of the Molecular Centre, R2*.- III.B. Radiative Decay of the Molecular Centre.- III.C. Origin of the Narrow Luminescence Lines.- IV. Photoluminescence Yield Spectra.- IV.A. PLY for Excitonic Excitations.- IV.B. PLY Spectra in the Range of Band-to-Band Transitions.- V. Luminescence of RGS with Isoelectronic Impurities.- References.- Luminescence Properties of Rare Gas Solids. II. Time-Resolved Luminescence Spectroscopy.- Abstract.- I. Introduction.- II. Radiationless Relaxation of Molecules in RGS Matrices.- II.A. Vibrational Energy Transfer and Relaxation of CO in Solid Neon and Argon.- II.B. Interstate Cascading in Matrix Isolated CN.- III. Relaxation Within Excited States of RGS.- III.A. Radiative States of Luminescence Centers in RGS.- III.B. Relaxation Processes in RGS.- III.C. Relaxation Times and Luminescence Emission Bands.- III.D. Electronic Relaxation Times and Energy Transfer Processes from Luminescence and Photoelectron Spectroscopy.- 1. Energy Transfer to Surface Layers and Substrates.- 2. Energy Transfer to Guest Atoms.- III.E. Time-Resolved Luminescence Spectroscopy and Electronic Relaxation.- References.- Reorientations of the Molecular Centers O2- and S2- in the Excited Electronic State.- Abstract.- I. Introduction.- II. Reorientation Mechanisms.- III. Reorientation in the Ground Electronic State.- IV. Reorientation in the Excited State.- V. Photostimulated Reorientations.- References.- Dynamical Jahn-Teller Effect on the Fine Structure Lines of Transition Metal Ions.- Relativistic Effects in Half-Filled Shells.- Short Seminars (Abstracts).- Theory of Impurity Light-Absorption Spectrum. The Urbach Rule.- The Greek Alphabet.- Sensitive Analytical Determinations of Fluorescent and Non-Fluorescent Ions by Laser-Excited Luminescence.- Luminescence of Some Impurity Magnetic Ion in A1N.- List of Contributors.