Electron Spin Resonance

1 Basic Principles of Electron Spin Resonance.- 1-1 Introduction.- 1-2 Energy of Magnetic Dipoles in a Magnetic Field.- 1-3 Quantization of Angular Momentum.- 1-4 Relation between Magnetic Moments and Angular Momenta.- 1-5 Interaction of Magnetic Dipoles with Electromagnetic Radiation.- 1-6 Characteristics of the g Factor.- Problems.- 2 Basic Instrumentation of Electron Spin Resonance.- 2-1 A Simple ESR Spectrometer.- 2-2 Choice of Experimental Conditions.- 2-3 Typical Spectrometer Arrangement.- 2-3a The Cavity System.- 2-3b The Source.- 2-3c The Magnet System.- 2-3d The Modulation and Detection Systems.- 2-4 Line Shapes and Intensities.- References.- Problems.- 3 Nuclear Hyperfine Interaction.- 3-1 Introduction.- 3-2 Origins of the Hyperfine Interaction.- 3-3 Energy Levels of a System with One Unpaired Electron and One Nucleus with I = 1/2.- 3-4 The Energy Levels of a System with S = 1/2 and I=1.- 3-5 Summary.- Problems.- 4 Analysis of Electron Spin Resonance Spectra of Systems in the Liquid Phase.- 4-1 Introduction.- 4-2 Energy Levels of Radicals Containing a Single Set of Equivalent Protons.- 4-3 ESR Spectra of Radicals Containing a Single Set of Equivalent Protons.- 4-4 ESR Spectra of Radicals Containing Multiple Sets of Equivalent Protons.- 4-5 Hyperfine Splittings from Other Nuclei with I = 1/2.- 4-6 Hyperfine Splittings from Nuclei with I > 1/2.- 4-7 Useful Rules for the Interpretation of Spectra.- 4-8 Other Problems Encountered in the ESR Spectra of Free Radicals.- 4-9 Second-order Splittings.- Problems.- 5 Interpretation of Hyperfine Splittings in ?-type Organic Radicals.- 5-1 Introduction.- 5-2 Molecular Orbital Energy Calculations.- 5-3 Unpaired Electron Distributions.- 5-4 The Benzene Anion and Its Derivatives.- 5-5 The Anions and Cations of the Polyacenes.- 5-6 Other Organic Radicals.- 5-7 Summary.- References-HMO Method.- Problems.- 6 Mechanism of Hyperfine Splittings in Conjugated Systems.- 6-1 Origin of Proton Hyperfine Splittings.- 6-2 Sign of the Hyperfine Splitting Constant.- 6-3 Extension of the Molecular Orbital Theory to Include Electron Correlation.- 6-4 Alkyl Radicals-A Study of Q Values.- 6-5 The Effect of Excess Charge on the Parameter Q.- 6-6 Methyl-proton Hyperfine Splittings-Hyperconjugation.- 6-7 Hyperfine Splitting by Nuclei Other than Protons.- Problems.- 7 Anisotropic Interactions in Oriented Systems with S = 1/2.- 7-1 Introduction.- 7-2 A Simple Example of Anisotropy of g.- 7-3 Systems with Orthorhombic or Lower Symmetry.- 7-4 Experimental Determination of the g Tensor in Oriented Solids.- 7-5 Anisotropy of the Hyperfine Coupling.- 7-6 Origin of the Anisotropic Hyperfine Interaction.- 7-7 Determination of the Elements of the Hyperfine Tensor.- 7-8 Corrections to Hyperfine Tensor Elements.- 7-9 Line Shapes in Nonoriented Systems.- 7-9a Line Shapes for Systems with Axial Symmetry.- 7-9b Hyperfine Line Shapes for an Isotropic g Factor, S = 1/2 and One Nucleus with I = 1/2.- Problems.- 8 Interpretation of the ESR Spectra of Systems in the Solid State.- 8-1 Generation of Free Radicals in Solids.- 8-2 ?-type Organic Radicals.- 8-2a Identification.- 8-2b Aliphatic Radicals.- 8-2c Radicals from Unsaturated Organic Compounds.- 8-3 ?-type Organic Radicals.- 8-4 Inorganic Radicals.- 8-4a Identification of Radical Species.- 8-4b Structural Information.- 8-5 Point Defects in Solids.- 8-5a Generation of Point Defects.- 8-5b Substitutional or Interstitial Impurities.- 8-5c Trapped-electron Centers.- 8-5d Trapped-hole Centers.- References.- Problems.- 9 Time-dependent Phenomena.- 9-1 Introduction.- 9-2 Spin-lattice Relaxation Time.- 9-3 Other Sources of Line Broadening.- 9-3a Inhomogeneous Broadening.- 9-3b Homogeneous Broadening.- 9-4 Mechanisms Contributing to Line Broadening.- 9-4a Electron Spin-Electron Spin Dipolar Interactions.- 9-4b Electron Spin-Nuclear Spin Interactions.- 9-5 Chemical Line-broadening Mechanisms.- 9-5a General Model.- 9-5b Electron-spin Exchange.- 9-5c Electron Transfer.- 9-5d Proton Exchange.- 9-6 Variation of Linewidths within an ESR Spectrum.- 9-6a Time-dependent Hyperfine Splitting for a Single Nucleus.- 9-6b Time-dependent Hyperfine Splittings for Systems with Several Nuclei.- 9-7 Spectral Effects of Slow Molecular Tumbling Rates.- 9-8 Spectral Effects of Rapid Molecular Tumbling Rates-Spin-rotational Interaction.- 9-9 Summary.- Problems.- 10 Energy-level Splitting in Zero Magnetic Field; The Triplet State.- 10-1 Introduction.- 10-2 The Spin Hamiltonian for S = 1.- 10-3 State Energies for a System with S = 1.- 10-4 The Spin Eigenfunctions for a System with S=1.- 10-5 Electron Spin Resonance of Triplet-state Molecules.- 10-6 Line Shapes for Randomly Oriented Systems in the Triplet State.- 10-7 The "?MS = 2" Transitions.- 10-8 Triplet Ground States.- 10-9 Carbenes and Nitrenes.- 10-10 Thermally Accessible Triplet States.- 10-11 Biradicals; Exchange Interaction.- 10-12 Systems with S > 1.- Problems.- 11 Transition-metal Ions. I..- 11-1 States of Gaseous Transition-metal Ions.- 11-2 Removal of Orbital Degeneracy in Crystalline Electric Fields.- 11-3 The Crystal Field Potential.- 11-4 The Crystal Field Operators.- 11-5 Crystal Field Splittings of States for P-, D- and F-state Ions.- 11-6 Spin-orbit Coupling and the Spin Hamiltonian.- 11-7 D- and F-state Ions with Orbitally Nondegenerate Ground States.- 11-7a D-state Ions 3d1(ttdl + ttgl) in 3d1(cubal + ttgl) 3d7(1s)(oct + ttgl); 3d9(oct + ttgl).- 11-7b F-state Ions 3d8(oct) 3d2(ttdl) 3d8(oct + ttgl) 3d2(ttdl + ttgl) 3d3(oct) 3d7(hs)(ttdl) 3d3(oct + ttgl).- 11-8 S-state Ions 3d5(hs)(oct) 3d5(hs)(oct + ttgl).- Problems.- 12 Transition-metal Ions. II. Electron Resonance in the Gas Phase.- 12-1 Ions in Orbitally Degenerate Ground States.- 12-1a D-state Ions 3d1(oct) 3d1(oct + ttgl), ? > > ? > > ? 3d1(oct + ttgl), ? > > ? ? ? 3d1(oct + trgl) 3d5(1s)(oct + ttgl) 3d9(ttdl + ttgl) 3d6(hs)(oct).- 12-1b F-state Ions 3d2(oct) 3d2(oct + trgl) 3d7(hs)(oct).- 12-1c Jahn-Teller Splitting 3d9(oct) 3d7(1s)(oct).- 12-2 Elements of the 4d and 5d Groups (Palladium and Platinum Groups).- 12-3 The Rare-earth Ions.- 12-4 The Actinide Ions.- 12-5 Deficiencies of the Point-charge Crystal Field Model; Ligand-Field Theory.- 12-6 Electron Resonance of Gaseous Free Radicals.- 12-7 The Practical Interpretation of ESR Spectra of Ions in the Solid State.- Problems.- 13. Double-resonance Techniques.- 13-1 An ENDOR Experiment.- 13-2 Energy Levels and ENDOR Transitions.- 13-3 Relaxation Processes in Steady-state ENDOR.- 13-4 An ENDOR Example: The F Center in the Alkali Halides.- 13-5 ENDOR in Liquid Solutions.- 13-6 ENDOR in Powders and Nonoriented Solids.- 13-7 Electron-electron Double Resonance.- Problems.- 14. Biological Applications of Electron Spin Resonance.- 14-1 Introduction.- 14-2 Substrate Free Radicals.- 14-3 Flavins and Metal-free Flavoproteins.- 14-4 Photosynthesis.- 14-5 Heme Proteins.- 14-6 Iron-sulfur Proteins.- 14-7 Spin Labels.- Appendix A. Mathematical Operations.- A-1 Complex Numbers.- A-2 Operator Algebra.- A-2a Properties of Operators.- A-2b Eigenvalues and Eigenfunctions.- A-3 Determinants.- A-4 Vectors: Scalar, Vector, and Outer Products.- A-5 Matrices.- A-5a Addition and Subtraction of Matrices.- A-5b Multiplication of Matrices.- A-5c Special Matrices and Matrix Properties.- A-5d Dirac Notation for Wave Functions and Matrix Elements.- A-5e Diagonalization of Matrices.- A-6 Tensors.- A-7 Perturbation Theory.- A-8 Euler Angles.- Problems.- Appendix B. Quantum Mechanics of Angular Momentum.- B-1 Introduction.- B-2 Angular-momentum Operators.- B-3 The Commutation Relations for the Angular-momentum Operators.- B-6 Angular-momentum Matrices.- B-7 Addition of Angular Momenta.- B-8 Summary.- Problems.- C-1 The Hamiltonian for the Hydrogen Atom.- C-2 The Spin Eigenfunctions and the Energy Matrix for the Hydrogen Atom.- C-3 Exact Solution of the Determinant of the Energy Matrix (Secular Determinant).- C-4 Selection Rules for High-field Magnetic-dipole Transitions in the Hydrogen Atom.- C-5 The Transition Frequencies in Constant Magnetic Field with a Varying Microwave Frequency.- C-6 The Resonant Magnetic Fields at Constant Microwave Frequency.- C-7 Calculation of the Energy Levels of the Hydrogen Atom by Perturbation Theory.- C-8 Wave Functions and Allowed Transitions for the Hydrogen Atom at Low Magnetic Fields.- Problems.- Appendix D. Experimental Methods; Spectrometer Performance.- D-1 Sensitivity.- D-2 Factors Affecting Sensitivity and Resolution.- D-2a Modulation Amplitude.- D-2b Modulation Frequency.- D-2c Microwave Power Level.- D-2d The Concentration of Paramagnetic Centers.- D-2e Temperature.- D-2g Microwave Frequency.- D-2h Signal Averaging.- D-3 Absolute Intensity Measurements.- Problems.- Table of Symbols.- Name Index.