Electron paramagnetic resonance of gamma-irradiated single crystals of two isobutyric acid derivatives

Abstract

The electron paramagnetic resonance spectra of gamma-irradiated alpha-hydroxy isobutyric acid, (CH3)(2)C(OH)COOH and alpha-amino isobutyric acid hydrochloride, (CH3)(2) C(NH2)COOH . HCl, single crystals and powders were investigated at 300 K and 113 K. The radiation damage centers in both compounds were attributed to the (CH3)(2)COOH radical. The hyperfine coupling constants of the six hydrogens of the two methyl groups were found to be equivalent, isotropic and 22.2 G at room temperature. However, at 113 K the hyperfine coupling constants of the methyl groups displayed a slightly anisotropic behavior. The g values were found to be isotropic and g = 2.0028 and g = 2.0032 respectively for the alpha-hydroxy isobutyric acid and alpha-amino isobutyric acid hydrochloride between 300 and 113 K. (C) 1997 Elsevier Science Ltd.