Evidence for disorder in L-alanine lattice detected by Pulsed-EPR spectroscopy at cryogenic temperatures.
The unusual behavior of lattice dynamics of L-alanine has been assigned to intermolecular dynamics and localization of vibrational energy. Recent heat capacity and Pulsed-EPR measurements support presence of thermally activated dynamic orientational disorder in the L-alanine lattice below 20 K. In the present study, the additional evidence for possible thermally activated disordered behavior of L-alanine lattice have been obtained by investigating dependences of longitudinal relaxation time of first stable L-alanine radical, SAR1, on sample cooling rates for the same low temperature interval. The obtained relaxation time by Pulsed-EPR shows clear dependence on cooling rates and this behavior can be explained within two types of suggested spin-lattice relaxation mechanisms for the paramagnetic centers in the hydrogen-bonded organic crystal.
Maltar-Strmecki
N
N
Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002 Zagreb, Croatia.
Rakvin
B
B
D000409:Alanine / Q000737:chemistry* / Q000528:radiation effects*; D003080:Cold Temperature; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006860:Hydrogen Bonding; D008433:Mathematics; D013113:Spin Labels
D013113:Spin Labels; D000409:Alanine