Electron Paramagnetic Resonance of Exchange Coupled Systems

ISBN-13: 9783642746017 / Angielski / Miękka / 2011 / 287 str.

Alessandro Bencini; Dante Gatteschi

Opis

The subject of this book is EPR Spectroscopy of systems in which two or more spins are magnetically coupled. These systems are relevant to many different scientific areas, ranging from chemistry to solid state physics and to biology. The book is based on the spin hamiltonian approach and extensive use is made of irreducible tensor techniques. The most novel feature is that for the first time the whole field is brought together including pairs, oligonuclear species and infinite species, in an attempt to provide a unitary approach. The book collects in one place information which up to now has been scattered in many different original papers, reviews and books.

Spis treści

1 Exchange and Superexchange.- 1.1 The Exchange Interaction.- 1.2 Anderson’s Theory.- 1.3 Molecular Orbital Exchange Models.- 1.4 Quantitative MO Calculations of Singlet-Triplet Splitting.- 2 Spin Hamiltonians.- 2.1 The Spin Hamiltonian Approach.- 2.2 The Magnetic Spin-Spin Interaction.- 2.3 The Exchange Contribution.- 2.4 Biquadratic Terms.- 2.5 Justification of the Spin Hamiltonian Formalism.- 2.6 Exchange Involving Degenerate States.- 2.7 Exchange in Mixed Valence Species.- 3 Spectra of Pairs.- 3.1 The Spin Hamiltonian for Interacting Pairs.- 3.2 Spin Levels in the Strong Exchange Limit.- 3.3 Spectra of Pairs in the Strong Exchange Limit.- 3.4 Spin Levels in the Weak Exchange Limit.- 3.5 Spectra of Pairs in the Weak Exchange Limit.- 3.6 Intermediate Exchange.- 4 Spectra of Clusters.- 4.1 The Spin Hamiltonian for Oligonuclear Systems of Interacting Spins.- 4.2 Spin Levels of Exchange Coupled Clusters in the Strong Exchange Limit.- 4.2.1 Spin Levels of Trinuclear Clusters.- 4.2.2 Spin Levels of Tetranuclear Clusters.- 4.2.3 Spin Levels of Linear Clusters.- 4.3 EPR Spectra of Exchange Coupled Clusters in the Strong Exchange Limit.- 4.3.1 EPR Spectra of Trinuclear Clusters.- 4.3.2 EPR Spectra of Tetranuclear Clusters.- 5 Relaxation in Oligonuclear Species.- 5.1 Introduction.- 5.2 Theoretical Basis of Spin Relaxation in Pairs.- 5.3 Iridium (IV) Pairs.- 5.4 Copper Pairs.- 5.5 Two-Iron-Two-Sulfur Ferredoxins.- 5.6 Relaxation in Larger Clusters.- 6 Spectra in Extended Lattices.- 6.1 Exchange and Dipolar Interactions in Solids.- 6.2 Exchange Narrowing.- 6.3 Additional Broadening Mechanisms.- 6.4 Exchange Narrowing in Lower Dimensional Systems.- 6.4.1 The Effect of Weak Interchain Coupling.- 6.4.2 Half-Field Transitions.- 6.4.3 Temperature Dependence of the Spectra.- 6.4.4 Frequency Dependence of the Line Widths.- 7 Selected Examples of Spectra of Pairs.- 7.1 Early Transition Metal Ion Pairs.- 7.2 Copper Pairs.- 7.3 Heterometallic Pairs.- 7.4 Organic Biradicals.- 8 Coupled Transition-Metal Ions-Organic Radicals.- 8.1 Introduction.- 8.2 Nitroxides Directly Bound to Metal Ions.- 8.3 Weak Exchange with Nitroxides.- 8.4 Semiquinones.- 9 Biological Systems.- 9.1 Introduction.- 9.2 Copper Proteins.- 9.3 Iron Proteins.- 9.3.1 Iron Porphyrins and Heme Proteins.- 9.3.2 Iron-Sulfur Proteins.- 9.3.3 Sulfite Reductase.- 9.3.4 Nitrogenase.- 9.3.5 Iron-Binding Proteins Without Cofactors or Sulfur Clusters.- 9.4 Exchange-Coupled Species in the Photosynthetic O2-Evolving Complexes.- 10 Low Dimensional Materials.- 10.1 Linear Chain Manganese(II).- 10.2 Linear Chain Copper(II).- 10.3 Two-Dimensional Manganese(II).- 10.4 Two-Dimensional Copper(II).- 11 Excitons.- 11.1 Introduction.- 11.2 Excitons.- 11.3 EPR of Triplet Excitons in Linear Organic Radical Systems.- Appendix A. Second Quantization.- Appendix B. Properties of Angular Momentum Operators and Elements of Irreducible Tensor Algebra..- B.1 Properties of Angular Momentum Operators.- B.2 Addition of Two Angular Momenta. Clebsch-Gordon Coefficients and “3j” Symbols.- B.2.1 Definitions.- B.2.1.1 Equivalent Definitions.- B.2.1.2 Phase Convention and Properties.- B.2.1.3 The “3J” Symbols.- B.2.2 Methods of Calculations.- B.2.2.1 Special Formulae.- B.3 The “6j” Symbols and the Racah W Coefficients.- B.3.1 Definitions.- B.3.2 Properties.- B.3.3 Methods of Calculation.- B.3.3.1 Special Formulae.- B.4 The “9j” Symbols.- B.4.1 Definition.- B.4.2 Properties.- B.4.3 Special Formulae.- B.5. Irreducible Tensor Operators.- B.5.1 Definitions.- B.5.1.1 Compound Irreducible Tensor Operators.- B.5.1.2 Tensor Product of Two First-Rank Irreducible Tensor Operators.- B.5.2 Properties of Irreducible Tensor Operators.- B.5.3 Reduced Matrix Elements of Special Operators.