1 Some Principles Governing the Luminescence of Organic Molecules.- 1. Introduction.- 2. Spontaneous Emission.- 2.1. Relationship Between Lifetime and Absorption Coefficient.- 2.2. Influence of Multiplicity on Observed Lifetime.- 2.3. Luminescence from Nearby States.- 2.4. Multiple-State Decay: An Example.- 3. Molecular Luminescence Characteristics.- 3.1. The Transition Dipole Moment.- 3.2. Spontaneous Luminescence in Aggregates.- 4. The Adiabatic Approximation.- 4.1. Dependence of Transition Moment on Nuclear Displacements.- 4.2. Effect of Nuclear Displacements on the Emission Spectrum and Lifetime.- 4.3. Numerical Estimates of Vibronic Effects.- 5. Triplet-Singlet Transitions and Selection Rules.- 5.1. The Mixing of ??* and n?* States.- 6. Relaxation Processes in Molecules.- 6.1. Vibrational Relaxation.- 6.2. Electronic Relaxation.- 6.3. Intersystem Crossing.- 6.4. Spin Polarization.- References.- 2 Experimental Techniques.- A Fluorescence Instrumentation and Methodology.- 1. Basic Considerations.- 1.1. General Description of a Spectrofluorimeter.- 1.2. Representation of Spectra.- 1.3. Calculation of Quantum Yields.- 1.4. Polarization Spectra.- 2. Methodology.- 2.1. Instrument Calibration.- 2.2. Correction for Sample Variations.- 2.3. Cuvettes.- 3. Criteria for a Spectrofluorimeter.- 3.1. Sensitivity.- 3.2. Resolution.- 3.3. Sample Compartment.- 3.4. Photomultipliers.- 3.5. Amplifiers.- 3.6. Summary.- References.- B Direct Measurement of Fluorescence Lifetimes.- 1. Introduction.- 2. Instrumentation.- 2.1. Instrument Considerations.- 2.2. Oscilloscope Techniques.- 2.3. Curve Normalization Techniques.- 2.4. Gated Photomultiplier Detection.- 2.5. Single-Photon Counting.- References.- C Phosphorescence Instrumentation and Techniques.- 1. General Instrumentation.- 1.1. Light Choppers.- 1.2. Photomultipliers.- 1.3. Sample-Cooling Devices.- 2. Matrices.- 3. Population of the Triplet State.- 3.1. Spectra.- 3.2. Quantum Yields.- 3.3. Lifetimes.- 3.4. Polarization of Phosphorescence.- References.- 3 The Excited States of Nucleic Acids.- 1. History and Introduction.- 2. Structures, Nomenclature, and Abbreviations.- 3. Excited States of Monomers.- 3.1. Relevance of Low-Temperature Experiments.- 3.2. Emission Spectra and Other Experimental Parameters.- 3.3. Sensitized Phosphorescence Spectra.- 3.4. Wavefunctions of the Excited States.- 4. Excited States of Oligonucleotides and Polynucleotides at Low Temperature.- 4.1. Types of Interactions.- 4.2. Excited States of Dinucleotides.- 4.3. Excited States of Polynucleotides.- 5. Excited States at Room Temperature.- 5.1. Energy Levels.- 5.2. Nonradiative Rates in Aqueous Solution.- 5.3. Triplet-State Molecules in Aqueous Solution.- 5.4. Temperature Dependence of Fluorescence.- 5.5. Speculations about Fluorescence Quenching and Temperature Effects.- 6. Excited-State Precursors of Photoproducts.- 6.1. Photohydrates.- 6.2. The Cytosine-Thymine Adduct.- 6.3. Photodimers of Pyrimidines.- 6.4. Sensitized Pyrimidine Dimers in Polynucleotides.- 7. Energy Transfer in Polynucleotides.- 7.1. General Considerations.- 7.2. Theory of Energy Transfer.- 7.3. Förster Energy Transfer.- 7.4. Experiments and Calculations.- 8. Transfer RNA.- 8.1. The Role of Odd Bases.- 8.2. tRNAPhe Studies.- References.- 4 Fluorescent Protein Conjugates.- 1. Introduction.- 2. Chemistry of Conjugation.- 2.1. Functional Groups in Proteins and in the Label.- 2.2. Dye Structures.- 3. Experimental Procedures for Labeling.- 3.1. Conditions of Labeling.- 3.2. Isolation of the Labeled Conjugate.- 3.3. Determination of the Degree of Labeling.- 3.4. Fractionation According to the Degree of Labeling.- 4. Effect of the Label on the Properties of the Protein.- 5. Excitation and Emission Spectra.- 5.1. Spectral Data.- 5.2. Changes Due to Alterations in Environment of the Dye Molecule.- 5.3. Electronic Mechanisms Responsible for Changes.- 5.4. Changes Due to Photochemical Reactions.- 6. Lifetime, Decay Time, and Quantum Yield.- 7. Energy Transfer.- 8. Polarization of Fluorescence.- 9. Visible Tracing.- 9.1. Coons Fluorescent Antibody Technique.- 9.2. Quantitative Precipitation Test.- 9.3. N-Terminal Analysis.- 10. Noncovalently Bound Labels.- References.- 5 The Luminescence of the Aromatic Amino Acids.- 1. Introduction.- 2. Excitation of the Aromatic Amino Acids.- 2.1. Excitation by Near-Ultraviolet Radiation: Ultraviolet Absorption Spectra.- 2.2. Excitation by Higher-Energy Radiation.- 3. Environmental Effects upon the Fluorescence of the Aromatic Amino Acids.- 3.1. Temperature.- 3.2. Physical State.- 3.3. Solvent.- 4. Fluorescence Quantum Yields and Lifetimes for the Aromatic Amino Acids.- 5. Fluorescence of Derivatives of the Aromatic Amino Acids.- 5.1. Tryptophan Derivatives.- 5.2. Tyrosine Derivatives.- 5.3. Phenylalanine Derivatives.- 5.4. Oligopeptides Containing Tryptophan and/or Tyrosine.- 6. Radiationless Deactivation of the Excited State.- 7. Phosphorescence of the Aromatic Amino Acids.- 7.1. Temperature Dependence and Solvent Dependence.- 7.2. Tryptophan.- 7.3. Tyrosine.- 7.4. Phenylalanine.- 8. Polarization of Luminescence.- 8.1. Theory.- 8.2. Phenol and Tyrosine.- 8.3. Indole and Tryptophan.- 9. Energy Transfer in Oligopeptides.- 9.1. Radiationless Exchange.- 9.2. Intermolecular Transfer.- 9.3. Intramolecular Transfer in Tyrosine Oligopeptides.- 9.4. Intramolecular Transfer in Oligopeptides Containing Tryptophan and Tyrosine.- 10. Thermoluminescence of the Aromatic Amino Acids.- References.- 6 Luminescence of Polypeptides and Proteins.- 1. Historical Survey.- 1.1. Existence of Excited States.- 1.2. Protein Fluorescence.- 2. Luminescence of Synthetic Polypeptides.- 2.1. Chemistry and Stereochemistry of Polypeptides.- 2.2. Homopolypeptide Luminescence.- 2.3. Heteropolymer Luminescence: Aromatic Amino Acid Systems.- 2.4. Quenching Studies.- 2.5. Photochemistry of Polytyrosine.- 3. Luminescence of Natural Polypeptides: Hormones and Antibiotics.- 3.1. Phenylalanine Systems.- 3.2. Tyrosine-Containing Polypeptides.- 3.3. Tryptophan-Containing Polypeptides.- 3.4. Summary.- 4. Luminescence of Proteins—Class A Proteins.- 4.1. Fluorescence Spectra.- 4.2. Fluorescence Quenching.- 4.3. Phosphorescence.- 4.4. Fluorescence Lifetime.- 4.5. Phosphorescence Lifetime.- 4.6. Temperature-Induced Quenching.- 4.7. Acid Denaturation.- 4.8. Muscle Proteins.- 4.9. Summary.- 5. Luminescence of Proteins—Class B Proteins.- 5.1. Introduction.- 5.2. Tyrosine Fluorescence.- 5.3. Tyrosine Fluorescence and Phosphorescence Spectra.- 5.4. Tyrosine Quantum Yield.- 5.5. Excitation Spectra of Tyrosine.- 5.6. Tyrosine Phosphorescence Yield and Decay Time.- 5.7. Electronic Energy Transfer.- 5.8. Fluorescence Polarization Spectra.- 5.9. Phosphorescence Polarization Studies.- 5.10. Tryptophan Excitation Spectra.- 5.11. Quantum Yields of Tryptophan Residues.- 5.12. Solvent Perturbation.- 5.13. Solvent Isotopic Effect.- 5.14. Temperature Dependence of Quantum Yields.- 5.15. Energy Loss at 77°K.- 5.16. Luminescence Lifetimes.- 5.17. Fluorescence Spectra of Protein Tryptophan Residues.- 5.18. Phosphorescence Spectra of Tryptophan.- 5.19. Stokes’ Shift of Fluorescence.- 5.20. Heterogeneity of Environment.- 5.21. Heterogeneity of Phosphorescence.- 5.22. Transfer and Heterogeneity.- References.