Hyperfine Interactions of Radioactive Nuclei

ISBN-13: 9783642819711 / Angielski / Miękka / 2011 / 368 str.

J. Christiansen

Opis

This volume deals with the interaction between moments of excited or radioactive nuclei and electromagnetic fields. The experimental techniques developed for the observation of this hyperfine interaction are governed by the lifetime of the nuc lear states in question. The dynamics of the interaction are reflected by the time dependence of the spatial distribution of the radioactive decay radiation. Basically, the experiments yield information on the energy shifts and/or splittings of the nuc lear levels. These quantities are determined essentially by the product of the nuc lear moment and the electromagnetic field acting at the site of the nucleus. Due to the strong decrease in the fields with distance, the measurements probe these fields within a highly localized region centered around the radioactive nuclei. Detailed experimental methods with numerous ramifications were developed in the early sixties. In the period which followed, the main emphasis was on excitation of short-lived nuclear states by means of pulsed particle accelerators, implantation of radioactive nuclei, and production of polarized a-unstable nuclei by nuclear re actions with polarized neutrons or particles. The seventies were a period of fruit ful applications directed to extensive studies of the moments of excited nuclear states on the one hand, and local internal fields on the other, resulting in far reaching information on atomic and solid-state properties. The organization of this Topics volume follows these main lines of research."

Spis treści

1. Introduction.- 1.1 Perturbed Angular Distribution Techniques.- 1.1.1 Magnetic Hyperfine Interaction.- 1.1.2 Electric Quadrupole Hyperfine Interaction.- 1.1.3 The Stroboscopic Method.- 1.2 Perturbed Angular Correlation Techniques.- 1.3 Nuclear Magnetic Resonance on ?-Emitting Nuclei.- References.- 2. Hyperfine Interactions of Excited Nuclei in Atomic Systems.- 2.1 Free Atoms in Flight-The Recoil Distance Method.- 2.1.1 Calculation of the Perturbation Function GKK(t).- 2.1.2 Fine-Structure Beats.- 2.1.3 Hyperfine Interactions in Free Atoms.- 2.1.4 Hydrogenlike Atoms.- 2.1.5 He-Like Atoms.- 2.1.6 Li-Like Atoms.- 2.1.7 Na-Like Atoms.- 2.1.8 Other Atomic Systems in Vacuum.- 2.2 Atoms in Gases.- 2.2.1 Fast Atoms in Gases.- 2.2.2 Statistical Approach.- 2.2.3 Nuclear Spin Dependence.- 2.2.4 Relaxing the Condition 1/2?C «1.- 2.2.5 The Approach to Thermal Equilibrium-Chemical Effects.- 2.2.6 Thermalized Atoms in Rare-Gas Hosts.- 2.2.7 Pressure Dependence of the Alignment.- 2.2.8 Magnetic Field Dependence.- 2.3 Magnetic Decoupling Measurements in Vacuum.- 2.3.1 Fields Parallel to the Quantization (Beam) Axis.- 2.3.2 Strong Magnetic Fields Transverse to the Beam Direction.- 2.4 New Methods and Future Directions.- References.- 3. Hyperfine Interaction Studies in Nuclear Physics.- 3.1 Overview.- 3.2 Hyperfine Hamiltonian and Nuclear Moments.- 3.2.1 Atomic Isotope Shifts and Nuclear Mean-Square Radii.- 3.2.2 Quadrupole Interactions and Nuclear Quadrupole Moments.- a) Quadrupole Interactions in Atoms.- b) Quadrupole Interaction Non-Cubic Lattices.- c) Calibration of Electric Field Gradients.- 3.2.3 Magnetic Interactions and Nuclear Magnetic Moments.- a) Magnetic Interactions in Atoms.- b) Magnetic Interactions in Solids.- 3.3 Laser Spectroscopy and Hyperfine Structure of Exotic Nuclear States.- 3.4 Nuclear Moments of High-Spin States.- 3.4.1 The Deformation of High-Spin Yrast Isomers.- 3.4.2 The g Factors of Collective High-Spin States.- 3.5 Magnetic Moments of Simple Shell-Model Configurations.- 3.5.1 Meson Exchange Currents.- 3.5.2 First-Order Core Polarization.- 3.5.3 High-Spin Isomers of Two-Particle Configuration.- 3.5.4 Single-Particle States in Other Mass Regions.- 3.5.5 Core-Polarization Blocking.- 3.5.6 Second-Order Core Polarization.- 3.5.7 Magnetic Moments of ? Emitters.- 3.6 Hyperfine Interactions in Nuclear ? Decay.- 3.6.1 Theoretical Position.- 3.6.2 Experimental NMR Techniques for ? Emitters.- 3.6.3 Experimental Results.- 3.6.4 Discussion.- References.- 4. Hyperfine Interactions of Defects in Metals.- 4.1 Relevant Solid State and Nuclear Physics Aspects.- 4.1.1 Defects in Metals.- a) Defects After Irradiation.- b) Defects in Thermal Equilibrium.- c) Vacancy and Interstitial Configurations.- d) Migration of Defects.- e) Interaction of Lattice Defects with Impurity Atoms.- f) Some Experimental Aspects in the Determination of Defect Properties.- 4.1.2 Hyperfine Interaction Parameters.- a) Electric Hyperfine Interaction.- b) Magnetic and Combined Hyperfine Interaction.- 4.1.3 Nuclear Probes.- 4.2 Hyperfine Investigations of Defects.- 4.2.1 Experiments with Radioactive Sources.- a) Diamagnetic fcc Metals.- b) Diamagnetic bcc Metals.- c) Ferromagnetic Cubic Metals.- d) Hcp Metals.- e) Summary.- 4.2.2 In-Beam Experiments.- a) Cubic Metals.- b) Noncubic Metals.- c) Summary of Nuclear Reaction Experiments.- References.- 5. Electric Quadrupole Interaction in Noncubic Metals.- 5.1 Electric Quadrupole Hyperfine Interaction.- 5.2 Experimental Methods.- 5.2.1 Energy Methods.- a) Specific Heat Measurements.- b) Nuclear Orientation.- c) Mossbauer Effect.- 5.2.2 Precession Methods.- a) Nuclear Resonance Methods.- b) Perturbed Angular Correlation (Distribution) Methods.- 5.3 Experimental Data and Systematic Trends.- 5.3.1 The Universal Correlation.- 5.3.2 The Temperature Dependence of the EFG.- 5.3.3 The Pressure Dependence of the EFG.- 5.3.4 Impurity Valence Effects of the EFG.- 5.4 The EFG in Metals.- 5.4.1 Anti shielding.- 5.4.2 The Lattice Sum.- 5.4.3 Wave Function Approaches.- a) Wannier Functions.- b) Augmented Plane Waves.- c) Orthogonalized Plane Waves.- d) Fermi Surface Electrons.- 5.4.4 Potential Approaches.- 5.4.5 Temperature Dependence.- a) Fermi Surface Electrons.- b) Wave Function Approach.- c) Potential Approach.- 5.4.6 Pressure and Concentration Dependence.- 5.5 Conclusion.- 5.6 Appendix.- Table of Experimental Data on Quadrupole Interaction in Noncubic Metals.- References.- 6. ? Emitters and Isomeric Nuclei as Probes in Condensed Matter.- 6.1 Theory.- 6.1.1 Hamiltonian and Energy Levels.- 6.1.2 Reorientation in Electromagnetic Fields.- 6.1.3 Relaxation.- a) Nuclear Relaxation by Magnetic Coupling to Conduction Electrons.- b) Relaxation by Fluctuating Nuclear Dipole-Dipole Interactions.- c) Quadrupolar Relaxation Induced by Atomic Motion.- d) Relaxation by Quadrupolar Spin-Phonon Coupling.- 6.2 Experimental Methods.- 6.2.1 Experiments Using ? Emitters.- a) Probe Creation by Capture of Polarized Thermal Neutrons.- b) Probe Creation by Fast Particle Reactions with Selected Recoil Angle.- c) Probe Creaction by Reactions with Polarized Fast Particles.- d) Probe Creation by Fast Particle Reactions and Subsequent Polarization in the Stopper.- 6.2.2 Experiments Using Isomeric ? Emitters.- 6.3 Metals.- 6.3.1 Static Interactions, NMR Spectra.- a) Magnetic Energy Splitting.- b) Energy Splitting in the Presence of Quadrupole Interactions.- 6.3.2 Relaxation of Nuclear Orientation.- a) Solid Metals.- b) Liquid Metals.- 6.4 Insulators.- 6.4.1 Static Interactions, NMR Spectra.- a) Lithium Compounds.- b) Fluorine Compounds.- c) Probe Nuclides in the Mass Number Range 24 ? A ? 39.- d) Indium and Silver Compounds.- 6.4.2 Relaxation of Nuclear Orientation.- a) Lithium and Fluorine Compounds.- b) Indium and Silver Compounds.- 6.5 Tabular Summary.- References.