HYPERFINE ABSORPTION SPECTRUM OF CH(COOH)(2).

It has been shown elsewhere1 2, that it is possible to produce oriented radicals with the formula CH(COOH)2 in single crystals of malonic acid by subjecting these crystals to 50 kv. X-ray damage at room temperature. The orientation of the CH(COOH)2 radical in the crystal lattice, and its electronic structure, was investigated by an analysis of the anisotropy of the proton" 2 and carbon-133 hyperfine structure that was observed in the paramagnetic resonance at X-band (9,500 Mc, 3400 gauss) and at K-band (24,100 Mc, 8600 gauss). The proton hyperfine interaction involves the CH group proton, and is described by the spin Hamiltonian,