The relaxation times T2,' characterizing the allowed and T2'', characterizing the forbidden and coherence cross resonances, during free evolutions over the coherent pathways p = ±1 are estimated from the SECSY (Spin Echo Correlation Spectroscopy) signal of the electron-nuclear spin-coupled system in a γ-irradiated malonic acid single crystal. This is accomplished by fitting the intensities of the two main peaks in the Fourier transform of the SECSY signal reported by Lee, Patyal and Freed (J. Chem. Phys. 98, 3665 (1993)) to T2' and T2''. The values of the fitted relaxation times T2'=500 ns, T2"=50,000 ns, reveal that the relaxation via the allowed resonance is two orders of magnitude faster than that via the forbidden and cross resonances. Full details of the calculation exploiting the Liouville von Neumann equation are presented.
PACS: 76.30.-v, 76.70.Dx