title: Four complementary theoretical approaches for the analysis of NMR paramagnetic relaxation.
abstract: Four theoretical and computational approaches used at the University of Michigan to analyze NMR paramagnetic relaxation enhancement (NMR-PRE) are described. The primary objective of the theory is to describe the relationship of the NMR-PRE phenomenon to the electron spin hamiltonian and the spin energy level structure when zero field splitting interactions are significant. Four formulations of theory are discussed: (1) spin dynamics simulation; (2) the laboratory frame "constant H(S)" formulation; (3) the Molecular Frame "constant H(S)" formulation; and (4) the zfs-limit "constant H(S)" formulation. No single theoretical approach describes all important aspects of the relaxation mechanism in a fully satisfactory way. We use the four formulations in a complementary manner to provide as complete a picture of the relaxation mechanism as possible. We also discuss the integration of NMR-PRE theory and recently developed theory of electron spin relaxation which accounts for effects of the permanent zfs hamiltonian.
authors: Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109, USA.
authors: Nathaniel
authors: N
authors: Schaefle
authors: Robert
authors: R
authors: Sharp
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D008670:Metals / Q000032:analysis* / Q000737:chemistry*; D008956:Models, Chemical
chemical_list: D008670:Metals