Electron Spin Resonance in an Irradiated Single Crystal of Dimethylglyoxime

Abstract

The paramagnetic resonance of gamma-irradiated single crystals of dimethylglyoxime has been measured at 23 kMc/sec and 9 kMc/sec for various orientations of the crystal in the magnetic field. The resonance pattern was found to have a triplet structure caused by coupling to a single N14 nucleus. Both the nuclear coupling and the spectroscopic splitting factor were found to be anisotropic with the principal values; A1=45±1 gauss, A2=A3=25±1 gauss, g1=2.0026±0.0003, g2=2.0063±0.0003, and g3=2.0095±0.0003. It is concluded that the free radical produced by the irradiation is probably the ionized dimethylglyoxime molecule, CH3–H¨–O–N=C–C=N+–O–H,–CH3with the positive charge and the electron spin density concentrated on one of the nitrogens and in an hybridized sp2 orbital which is approximately in the molecular plane and along the bisector of the C=N–O angle. The s character in the orbital is calculated from the N14 coupling to be 19%.