The ultraviolet effect on the alanine radicals and its resolution enhanced electron paramagnetic resonance powder pattern
College Park, Md.
American Institute of Physics (AIP)
AIP Digital Archive
Chemistry and Pharmacology
This study reports the electron paramagnetic resonance powder-line structure of γ-ray-induced DL-alanine radicals, and its changes when these radicals are exposed to ultraviolet (UV) light. Deconvolution results show that the resolution enhanced powder pattern of UV-free and UV-exposed alanine radicals may consist of five pairs of superimposed quintets on quartets, and a doublet whose line intensity is proportional to that of the quartets. From the analysis of such resolution enhanced powder patterns, one may expect that the four alanine radicals per unit cell could always be magnetically grouped by pairs, irrespective of any crystalline axis orientation with respect to the magnetic field. Additionally, as the γ-ray-irradiated powdered DL-alanine is UV-exposed, a line broadening effect concomitant to the signal loss of the strongest resonance line is observed. These spectral UV-time-dependent variations, as well as the near constancy of the total spectral area, might reject the coexistence of two alanine radical populations, but may suggest a recombination process among the alanine radicals of a single radical species population that is very stable at atmospheric conditions but UV-triggered.
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