title: Study of relaxation rates of stable paramagnetic centers in gamma-irradiated alanine.
abstract: The stable L-alanine radical induced by gamma-irradiation was examined by electron paramagnetic resonance (EPR), transfer saturation EPR and electron nuclear double resonance (ENDOR) in the temperature region of fast motion of the methyl group (180-320 K). From the obtained spectral line broadening and spectral intensity the correlation time for the methyl rotation was estimated. The complex processes determining the relaxation rate were examined in the same temperature interval. It was shown that important contributions to the relaxation rate arise from non-secular and pseudo-secular types of contributions. The non-secular contribution involves intramolecular dynamics while the pseudo-secular contribution originates from intermolecular motions. The obtained values for the dynamical parameters have been compared with those obtained by pulse EPR methods and by proton nuclear magnetic resonance (NMR) on undamaged crystals.
authors.affiliation: Ruder Bosković Institute, Zagreb, Croatia. rakvin@faust.irb.hr
authors.forename: B
authors.initials: B
authors.lastname: Rakvin
authors.forename: N
authors.initials: N
authors.lastname: Maltar-Strmecki
mesh_terms: D000409:Alanine / Q000737:chemistry* / Q000528:radiation effects*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005720:Gamma Rays; D009682:Magnetic Resonance Spectroscopy
chemical_list: D000409:Alanine