Interpretation of the EPR spectra of phosphoniumyl free radicals in solid state solutions

Abstract We present the EPR spectra of two new phosphorus centred free radicals in solutions. The spectra were performed in solid state frozen solutions and were interpreted with a simple model allowing to determine the isotropic and anisotropic parts of both the g factors and the hyperfine coupling. The high value of the isotropic hyperfine constant ( A ∼ 650 MHz) shows that these systems seem particularly suitable for low field measurements performed by Dynamic Nuclear Polarization (DNP) magnetometers.