Finally, in a recent paper , we show that even with aggregation of the trityl radicals the electron-electron interaction is not strong enough to induce triple spin flip for TM and the spin temperature of the C is completely decoupled from 1 H. The spin temperatures of C and 1 H can even have different signs with microwave irradiation. This proves that the electron-electron coupling is not strong enough to span the nuclear Larmor frequency of 1 H at 380 MHz so that 1 H and C can reside in the same electron spin bath.