Phase-Sensitive Two-Dimensional Heteronuclear Zero- and Double-Quantum-Coherence Spectroscopy.

New pulse sequences for two-dimensional phase-sensitive detection of heteronuclear zero- and double-quantum coherence are presented for use with and without pulsed field gradients. The magnetization is phase modulated during t1 and then transferred to a proton for detection using a novel approach similar to the sensitivity-enhancement technique [Palmer et al. J. Magn. Reson. 93, 151 (1991)]. These pulse sequences are useful for the measurement of size and relative sign of passive J couplings as well as for the measurement of the relaxation rates of zero- and double-quantum coherence. They can also be used as building blocks in multidimensional pulse sequences. The pulse sequences are tested on the peptide hormone motilin with a selectively 13C-enriched alpha carbon.