P‐Type gradient‐enhanced COSY experiments show lower t 1 noise than N‐type

Many of the perturbations that lead to t1 noise in 2D NMR spectroscopy cause fluctuations in the relative phases of pulses and coherences. Because the sensitivity of the phase of a coherence to changes in the phase of a pulse depends on the change of coherence order, P-type signals in homonuclear correlation experiments are insensitive to errors in the phase of the mixing pulse, and hence they show less t1 noise than N-type signals. This effect is illustrated for the gradient COSY experiment. © 1997 John Wiley & Sons, Ltd.