Electron Paramagnetic Resonance of Gamma-Irradiated Single Crystals of Two Isobutyric Acid Derivatives

Abstract

The electron paramagnetic resonance spectra of γ-irradiated α-hydroxy isobutyric acid, (CH<inf>3</inf>)<inf>2</inf>C(OH)COOH and α-amino isobutyric acid hydrochloride, (CH<inf>3</inf>)<inf>2</inf> C(NH<inf>2</inf>)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 (CH<inf>3</inf>)<inf>2</inf>ĊCOOH 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 α-hydroxy isobutyric acid and α-amino isobutyric acid hydrochloride between 300 and 113 K.; The electron paramagnetic resonance spectra of γ-irradiated α-hydroxy isobutyric acid, (CH<inf>3</inf>)<inf>2</inf>C(OH)COOH and α-amino isobutyric acid hydrochloride, (CH<inf>3</inf>)<inf>2</inf> C(NH<inf>2</inf>)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 (CH<inf>3</inf>)<inf>2</inf>CCOOH 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 α-hydroxy isobutyric acid and α-amino isobutyric acid hydrochloride between 300 and 113 K.