title: Multifrequency Pulsed EPR and the Characterization of Molecular Dynamics.
abstract: In fluid solution, motion-dependent processes dominate electron spin-lattice relaxation for nitroxides and semiquinones at frequencies between 250 MHz and 34 GHz. For triarylmethyl radicals, motion-dependent processes dominate spin-lattice relaxation at frequencies below about 3 GHz. The frequency dependence of relaxation provides invaluable information about dynamic processes occurring with characteristic times on the order of the electron Zeeman frequency. Relaxation mechanisms, methods of measuring spin-lattice relaxation, and motional processes for nitroxide, semiquinone, and triarylmethyl radicals are discussed.
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA. Electronic address: seaton@du.edu.
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Eaton
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA.
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Eaton
mesh_terms: D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D004583:Electrons; D056004:Molecular Dynamics Simulation; D013113:Spin Labels
chemical_list: D013113:Spin Labels
keywords: Intramolecular motions; Inversion recovery; Molecular tumbling; Saturation recovery; Solvent motions