? irradiated some isobutyric acid derivatives

This study consists of four parts. In the first part, y-irradiated single crystals of N-Acetyl and N-Carbamyl-y-Ammoisobutyric Acid were investigated by EPR For both samples, the spin-flip transitions were observed from the values determined at room temperature and 113 K. The paramagnetic centre that occurred as a result of radiation was attributed to the (CHa^CCOOH radical for both molecules. Though g and A values of the radical calculated at room temperature were found to be isotropic, these values were found to be very slightly anisotropic at 1 13 K. In the second part of this thesis, y-irradiated N-Monochloroacetyl-a- Aminoisobutyric Acid was investigated by EPR. The EPR spectra of crystal exhibited mainly three different patterns. The radiation damage centre was attributed to the (CH3)2CCOOH radical. The EPR parameters of the radical were determined from the EPR spectra. As the third part of this study, a-Aminoisobutyric Acid Methyl Ester Hydrochloride and a-Methyl Aminoisobutyric Acid were irradiated by y-radiation. The EPR spectra of the y-irradiated powder samples were simulated, and the EPR parameters of the radicals were determined. It was concluded from the determined EPR parameters, that (Ctb^CXCOOCHs) and (CHs^CCOOH radicals occurred respectively in the patterns above. In the fourth part of this study, N-Trifouoroacetyl-a- Aminoisobutyric Acid was irradiated by y-radiation. The paramagnetic centre was attributed to the \ C - CF0 // 2 radical. Furthmore, when the magnetic field was along the (xy) and (xz) planes, four sites and along (yz) plane, two sites were observed. The EPR parameters of the radical were determined from the EPR spectra.