-Quadrupole resonance

In contrast to NMR the NQR results (quadrupole resonance frequency, relaxation) are determinded by the quadrupole moment of the nuclei with J>1/2 plus the electric field gradient (EFG) arising from on site (valence) and lattice (ionic model) contribution. The quadrupole resonance frequency could be evaluated from the field sweep NMR spectra.


-Zero field NMR

Here we are making use of the internal field in the (afm) fm ordered state. Due to large internal fields (up to 100 T in 3d systems) this allows to probe less sensitive (low abundance) and/or small gyromagnetic ratio nuclei (like 57 Fe).