title: A 2H NMR spin-lattice relaxation study of -NH+3 group dynamics in polycrystalline L-alanine.
abstract: The 2H spin-lattice relaxation times T1Z and T1Q of the -ND+3 group in polycrystalline L-alanine were measured over the temperature ranges 250-425 K and 300-425, respectively. The relaxation data were fitted to analytical expressions for three-fold reorientation, giving a correlation time tau(c) = 1.5 x 10(-14) s exp(40.2 kJ mol-1/RT), which is in good agreement with the results of a limited lineshape study. T 1Z values derived from numerical simulations, taking into consideration geometrical distortion of the -ND+3 group and experimental imperfections, are compared with values given by an analytical expression for three-fold jumps and with the experimental results. The extraction of average site quadrupolar coupling constants is discussed.
authors.affiliation: Department of Chemistry, University of York, Heslington, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Williams
authors.forename: R D
authors.initials: RD
authors.lastname: Keenan
authors.forename: T K
authors.initials: TK
authors.lastname: Halstead
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000465:Algorithms; D000641:Ammonia / Q000737:chemistry*; D003460:Crystallization; D003903:Deuterium; D004578:Electron Spin Resonance Spectroscopy; D009682:Magnetic Resonance Spectroscopy; D013696:Temperature
chemical_list: D000641:Ammonia; D003903:Deuterium; D000409:Alanine