Semiclassical Theory of the Effects of Internal Motions on the Linewidths in Electron Spin Resonance Spectra

A number of classical dynamical models are developed for describing the effects of internal rotational motions and solvent‐complex formation on the ESR hyperfine linewidths of free radicals in solution. These dynamical processes can lead to linewidth effects because they cause time‐dependent modulations of the isotropic hyperfine interactions of the different magnetic nuclei. An alternating linewidth effect, which has been observed in a number of recent studies, is predicted to result when there is an out‐of‐phase correlation between the hyperfine splittings ai(t) of equivalent nuclei. By equivalent nuclei here are meant those for which the time‐average splittings 〈ai(t) 〉Av are equal, and an out‐of‐phase correlation is one in which an increase in the instantaneous splitting from Nucleus i, ai(t), is correlated with a decrease in the splitting aj(t) from nucleus j. This out‐of‐phase correlation can result from a coupling of the mechanical motions of different rotating groups and also from the effects that...

[1]  J. Freed,et al.  Theory of Line Widths in Electron Spin Resonance Spectra: Motion of Methyl Groups , 1964 .

[2]  J. Freed,et al.  Line Shapes in Electron Spin Resonance Spectra , 1964 .

[3]  J. Freed,et al.  Alternating Linewidths and Related Phenomena in the Electron Spin Resonance Spectra of Nitro‐Substituted Benzene Anions , 1964 .

[4]  B. L. Barton,et al.  Signs of the Isotropic Hyperfine Splittings in the Electron Spin Resonance Spectrum of the Dihydropyrazine Cation Radical , 1964 .

[5]  J. Freed,et al.  Linewidth Studies in Electron Spin Resonance Spectra : The Para and Ortho Dinitrobenzene Anions , 1964 .

[6]  A. Balch,et al.  Study of Steric Effects by Electron Spin Resonance Spectroscopy and Polarography. Substituted Nitrobenzenes and Nitroanilines , 1964 .

[7]  G. Fraenkel,et al.  Analysis of the Electron Spin Resonance Spectra of Aromatic Nitrosubstituted Anion Radicals , 1963 .

[8]  A. Maki,et al.  Intramolecular Electron Transfer in Bis(p‐Nitrophenyl) Anions and Its Effect on Electron Spin Resonance Hyperfine Structure , 1963 .

[9]  J. Freed,et al.  Theory of Linewidths in Electron Spin Resonance Spectra , 1963 .

[10]  M. Goldstein.  Motion of a Brownian Particle in a Periodic Potential , 1963 .

[11]  J. Bolton,et al.  An electron resonance study of rotational isomerism in the naphthazarin semiquinone cation , 1963 .

[12]  J. Freed,et al.  Solvent Effects in Electron Spin Resonance Spectra , 1962 .

[13]  J. Freed,et al.  Alternating Linewidths in the ESR Spectra of Dinitrobenzene Anion Radicals , 1962 .

[14]  J. Freed,et al.  Anomalous Alternating Linewidths in ESR Spectra , 1962 .

[15]  A. Carrington.  Theory of line width alternation in certain electron resonance spectra , 1962 .

[16]  J. Bolton,et al.  Line width alternation in the electron spin resonance spectrum of the durosemiquinone cation , 1962 .

[17]  H. Carr,et al.  The Principles of Nuclear Magnetism , 1961 .

[18]  J. Ragle,et al.  STERIC EFFECTS ON NITROGEN HYPERFINE COUPLING IN METHYL SUBSTITUTED MONO- AND DINITROBENZENE ANION RADICALS , 1961 .

[19]  M. Karplus,et al.  THEORETICAL INTERPRETATION OF CARBON-13 HYPERFINE INTERACTIONS IN ELECTRON SPIN RESONANCE SPECTRA. Technical Note Report No. 9 , 1961 .

[20]  D. Kivelson.  Theory of ESR Linewidths of Free Radicals , 1960 .

[21]  J. Schreurs,et al.  Anomalous Relaxation of Hyperfine Components in Electron Spin Resonance. II , 1960 .

[22]  M. J. Stephen,et al.  Theory of Saturation in Electron Spin Resonance Spectra , 1960 .

[23]  J. Trotter.  The crystal structure of nitrobenzene at 30°C , 1959 .

[24]  J. Trotter.  The crystal structures of some mesitylene and durene derivatives. II. Nitromesitylene , 1959 .

[25]  J. I. Kaplan.  Generalized Bloch‐Type Equations for Chemical Exchange , 1958 .

[26]  F. Bloch.  Dynamical Theory of Nuclear Induction. II , 1956 .

[27]  J. T. Law,et al.  Russell Effect in Silicon and Germanium , 1956 .

[28]  Y. Ayant.  Fonction de corrélation d'une variable quantique , 1955 .

[29]  P. W. Anderson,et al.  A Mathematical Model for the Narrowing of Spectral Lines by Exchange or Motion , 1954 .

[30]  H. S. Gutowsky,et al.  Nuclear Magnetic Resonance Multiplets in Liquids , 1953 .

[31]  S. Rice.  Mathematical analysis of random noise , 1944 .

[32]  J. Pople,et al.  High-resolution nuclear magnetic resonance , 1959 .

[33]  Alfred G. Redfield,et al.  On the Theory of Relaxation Processes , 1957, IBM J. Res. Dev..