P-TYPE GRADIENT-ENHANCED COSY EXPERIMENTS SHOW LOWER T(1) NOISE THAN N-TYPE

Many of the perturbations that lead to t(1) noise in 2D NMR spectrosco py cause fluctuations in the relative phases of pulses and coherences. Because tile sensitivity of the phase of a coherence to changes in th e phase of a pulse depends on the change of coherence order, P-type si gnals in homonuclear correlation experiments are insensitive to errors in the phase of the mixing pulse, and hence they show less t(1) noise than N-type signals. This effect is illustrated for the gradient COSY experiment. (C) 1997 John Wiley & Sons, Ltd.