I-SPIN N-QUANTUM COHERENCES IN INS SPIN SYSTEMS EMPLOYED FOR E.COSY-TYPE MEASUREMENT OF HETERONUCLEAR LONG-RANGE COUPLING-CONSTANTS IN NMR

We propose a general NMR pulse scheme for conversion of I-spin multipl e-quantum coherence to I-spin single-quantum coherence in InS spin 1/2 systems that exploit large single-bond J(IS) coupling constants and e mploys rf pulses on the S spin which, however, is fully restored to it s original state after the process. This is essential for application in multidimensional pulse experiments for E.COSY-type extraction of he teronuclear long-range coupling constants. The new pulse scheme is der ived in a systematic way, by first considering an energy level diagram in which selective rotations are required to achieve the desired effe ct and then deriving nonselective pulse sequences that produce the sam e effect. (C) 1997 Elsevier Science B.V.