SUPPRESSION OF RADIATION DAMPING DURING SELECTIVE EXCITATION OF THE WATER SIGNAL - THE WANTED SEQUENCE

A new pulse sequence is presented allowing the use of long selective p ulses at the water frequency using standard equipment. Radiation dampi ng is suppressed during the pulse by the use of gradient echoes progra mmed between the single pulses of a DANTE train. This WANTED (water-se lective DANTE using gradients) sequence thus allows the observation of interactions with water without the use of special probe heads or fil tering of undesired resonances. By combining the WANTED sequence with NOESY, ROESY and NOESY-HSQC experiments, we obtain selective 1D and 2D spectra fit to the observation of chemical exchange and dipolar inter actions between water and protein protons.