Two-dimensional NMR spectroscopy

The idea of Jeener consists in the stepwise increasing of the evolution time .

This will allow to get an NMR signal under the aspect of a sampling of free precession signals of the type. These FID will differ from each other only by the period duration written under a matricial form

s( , ). The delay is the time between the first and the second pulse.

Fig. 9 : Sampling of signals of free precession of the type s(t2)

The first Fourier transform as a function of gives us an interferogram of the form (Fig. 10)

Fig. 10 : Interferogram of the form s(t2, w1)

A second Fourier transform, versus the second variable , gives an NMR spectrum with two frequencies dimensions F1 and F2.

The result of this two fold Fourier transform does not get two spectra and but only one spectrum as a function of two independent frequencies, exhibiting a peak with the coordinates . Thus, an aimantation evolving with the frequency in the time course has been converted in another coherence evolving with the frequency during the period .

Fig. 11 : NMR spectrum in two dimensions following the second Fourier transform

This double Fourier transform in both dimension yields thus a matrix (spectrum 3).