Hyperfine structure

About: Hyperfine structure is a research topic. Over the lifetime, 25836 publications have been published within this topic receiving 468624 citations.

Indirect exchange coupling of nuclear magnetic moments by conduction electrons

Abstract: A calculation is given of the indirect exchange ${\mathrm{I}}_{i}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{I}}_{j}$ type coupling of nuclear magnetic moments in a metal by means of the hyperfine interaction with the conduction electrons. The interaction appears to account qualitatively for the broad nuclear spin resonance lines observed in natural metallic silver. It is expected that the interaction may sharpen the resonances in pure isotopic specimens. The line shape of the minority isotope in a binary mixture may tend to be Gaussian, while that of the majority isotope may tend to be Lorentzian, if the indirect exchange interaction is dominant.

Microwave molecular spectra

Abstract: Introduction Theoretical Aspects of Molecular Rotation Microwave Transitions - Line Intensities and Shapes Diatomic Molecules Linear Polyatomic Molecules Symmetric-Top Molecules Asymmetric-Top Molecules The Distortable Rotor Nuclear Hyperfine Structure in Molecular Rotational Spectra Effects of Applied Electric Fields Effects of Applied Magnetic Fields Internal Motions Derivation of Molecular Structures Quadrupole Couplings, Dipole Moments, and the Chemical Bond Irreducible Tensor Methods for Calculation of Complex Spectra Appendixes Author Index Subject Index.

Anomalous Paramagnetism of Copper Acetate

Abstract: The paramagnetic resonance spectrum of copper acetate is anomalous in that it resembles that of an ion of spin 1, and its intensity decreases as the temperature is lowered. The latter is correlated with the decreasing susceptibility found by Guha (1951). The following hypo­theses are suggested: (1) the crystalline field acting on each copper ion is similar to that in other salts such as the Tutton salts; (2) isolated pairs of copper ions interact strongly through exchange forces, each pair forming a lower singlet state and an upper triplet state, the latter only being paramagnetic. On this basis both the fine structure and the hyperfine structure of the spectrum have a simple explanation, and the theory also predicts a small initial split­ting of the triplet state of the same order as that found experimentally. The unit cell of the crystal contains two differently oriented pairs of ions, and, using an empirical value for the exchange parameter, fair agreement with the susceptibility measurements of Guha is obtained.

Reference Data on Atoms, Molecules, and Ions

Abstract: 1. Introduction.- 2. Units of Physical Quantities.- 2.1 Systems of Units in Physics.- 2.2 Fundamental Physical Constants.- 2.3 Systems of Units Based on "Natural Standards".- 2.4 Tables of Conversion Factors.- I Atoms and Atomic Ions.- 3. Isotopic Composition, Atomic Mass Table and Atomic Weights of the Elements.- 3.1 Parameters of Stable and Long-Lived Isotopes.- 3.2 Atomic Weights of the Elements and Atomic Mass Table.- 4. Structure of Atomic Electron Shells.- 4.1 Electron Configurations and Ground-State Terms.- 4.2 The Periodic Table.- 4.3 Parameters of Wavefunctions for Valence Electrons in Atoms, Positive and Negative Ions.- 5. Energetics of Neutral Atoms.- 5.1 Ionization Potentials of Atoms.- 5.2 Quantum Defects of Atomic Rydberg States.- 5.3 Fine-Structure Splitting of Atomic Energy Levels.- 5.4 Hyperfine Structure of Atomic Energy Levels.- 5.5 Isotope Shifts of Low-Lying Atomic Levels.- 5.6 Atoms in Static Electric and Magnetic Fields. Atomic Polarizabilities and Magnetic Susceptibilities.- 6. Energetics of Atomic Ions.- 6.1 Ionization Potentials of Atomic Ions.- 6.2 Electron Affinities of Atoms.- 6.3 Energy Levels of Multiply Charged Atomic Ions.- 7. Spectroscopic Characteristics of Neutral Atoms.- 7.1 Low-Lying Atomic Terms.- 7.2 Diagrams of Atomic Energy Levels and Grotrian Diagrams.- 7.3 Atomic Oscillator Strengths in Absorption.- 7.4 Lifetimes of Resonant Excited States in Atoms.- 7.5 Energy Levels and Lifetimes for Metastable States in Atoms.- 7.6 Lifetimes of Atomic Rydberg States.- 8. Spectroscopic Characteristics of Atomic Positive Ions.- 8.1 Low-Lying Terms of Singly Ionized Atoms.- 8.2 Lifetimes of Resonant Excited States in Atomic Ions.- 8.3 Energy Levels and Lifetimes for Metastable States in Singly Ionized Atoms.- 8.4 Optical Parameters of Multiply Charged Atomic Ions.- II Molecules and Molecular Ions.- 9. Interaction Potentials Between Atomic and Molecular Species.- 9.1 Van der Waals Coefficients for Interatomic Multipole Interactions.- 9.2 Long-Range Exchange Interactions of Atoms.- 9.3 Short-Range Repulsive Interactions Between Atomic and Molecular Species.- 10. Diatomic Molecules.- 10.1 Electron Configurations of Diatomic Molecules.- 10.2 Asymptotic Parameters of Wavefunctions for Valence Electrons in Diatomic Molecules.- 10.3 Spectroscopic Constants of Diatomic Molecules.- 10.4 Potential Energy Curves.- 10.5 Ionization Potentials of Diatomic Molecules.- 10.6 Dissociation Energies of Diatomic Molecules.- 10.7 Lifetimes of Excited Electron States in Diatomic Molecules.- 10.8 Parameters of Excimer Molecules.- 10.9 Einstein Coefficients for Spontaneous Emission from Vibrationally Excited Diatomic Molecules.- 11. Diatomic Molecular Ions.- 11.1 Electron Configurations and Asymptotic Parameters of Wavefunctions for Valence Electrons in Diatomic Molecular Ions.- 11.2 Spectroscopic Constants of Diatomic Molecular Ions.- 11.3 Dissociation Energies of Diatomic Molecular Ions.- 11.4 Electron Affinities of Diatomic Molecules.- 11.5 Proton Affinities of Atoms.- 11.6 Lifetimes of Excited Electron States in Diatomic Molecular Ions.- 12. Van der Waals Molecules.- 12.1 Potential Well Parameters of Van der Waals Molecules.- 12.2 Potential Well Parameters of Van der Waals Molecular Ions.- 12.3 Ionization Potentials of Van der Waals Molecules.- 13. Polyatomic Molecules.- 13.1 Constants of Triatomic Molecules.- 13.2 Ionization Potentials of Polyatomic Molecules.- 13.3 Bond Dissociation Energies of Polyatomic Molecules.- 13.4 Lifetimes of Vibrationally Excited Polyatomic Molecules.- 14. Polyatomic Molecular Ions.- 14.1 Bond Dissociation Energies of Complex Positive Ions.- 14.2 Bond Dissociation Energies of Complex Negative Ions.- 14.3 Electron Affinities of Polyatomic Molecules.- 14.4 Proton Affinities of Molecules.- 15. Electrical Properties of Molecules.- 15.1 Dipole Moments of Molecules.- 15.2 Molecular Polarizabilities.- 15.3 Quadrupole Moments of Molecules.- Mathematical Appendices.- A. Coefficients of Fractional Parentage.- B. Clebsch-Gordan Coefficients.