Procédé de spectroscopie RMN avec dégradations d'induction prolongée de cohérences aux temps de vie longs

A Method for nuclear magnetic resonance (NMR) spectroscopy of a sample comprising the following steps: (a) excitation of long lived coherences (LLC) between the singlet state So and the central triplet state To of nuclei of the sample by initiating irradiation of the sample with an rf-field with carrier frequency É rf ; (b) sustaining of the LLC by maintaining the rf-irradiation during an interval Ä 2 (c) converting the LLC temporarily into observable magnetisation by interrupting the rf-irradiation during an observation interval Ä 3 ; (d) detecting NMR-signals during the observation interval Ä 3 ; is characterized in that (e) the observable magnetisation is reconverted back into LLC after the observation interval Ä 3 ;and steps (b) - (e) are repeated n times, with n is a positive integer. The method according to the invention allows obtaining ultra high-resolution spectra of long-lived coherences.