Electron Spin Resonance Study of Free Radical Formation in Irradiated Zinc Acetate Dihydrate.

An electron spin resonance analysis of irradiated zinc acetate dihydrate, ZnCH3COO2.2H2O has been made. The methyl radical,.CH3 has been identified in the spectra of polycrystalline samples irradiated at 77 deg. K and examined at 103 deg. K. The conversion of .CH3 into a radical tentatively identified as .CH2CO2 was observed. The conversion is believed to occur too rapidly to be observed in spectra of samples irradiated at 300 deg. K. The X, Y, Z components of the hyperfine interaction tensors of the alpha 1 and alpha 2 protons of .CH2CO2 have been tentatively determined to be -92 plus or minus 5, -64 plus or minus 5, -24 plus or minus 5 and -91 plus or minus 5, -60 plus or minus 5, -38 plus or minus 5Mc respectively. The X, Y, Z orthogonal axis system was formulated with the Z axis along the CH1 bond and the X axis perpendicular to Z and in the plane of the CH and CC bonds. The tensor elements were calculated from first order perturbation theory although second order lines of significant intensity were observed. The H1CH2 angle was found to be 123.5 deg. plus or minus 5 deg. The limits of error on tensor components and the bond angle were estimated. Orientations of the CH bonds were found to be rotated 90 deg. about the b axis from the location implied by the crystal structure. Author