A Comment on the Theory of Mixed-Frequency Electron-Spin Echo Envelope Modulation (MIF-ESEEM)

The theory of one-dimensional mixing-frequency electron-spin-echo envelope modulation (MIF-ESEEM) spectroscopy of disordered systems has been revised. In particular, the correct dependence of the position and width of the MIF-ESEEM peaks on the experimental parameters has been obtained, thus providing formulas which enable one to properly interpret the experimental data. The differences with the previously published analyses are discussed. The close relationship with the two-dimensional HYSCORE spectroscopy is remarked on. Experimental examples demostrate the main results.