[CH 3 (CH 2) 16 CH 2] 2 N+ have been studied at different microwave powers. An intense
damping peak is observed when the Rabi frequency Ω R falls in the vicinity of the Larmor
frequency of protons ω N. The experiments are interpreted by a model showing that the
damping (or Rabi) time τ R is directly associated with decoherence caused by electron-
nuclear cross relaxation in the rotating reference frame. This decoherence induces energy …