RADIATION DAMPING ARTIFACTS IN 2D COSY NMR EXPERIMENTS

An experimental and theoretical analysis of multiple-quantum (MQ)-like artifacts in 2D NMR spectra of water is presented and discussed. Duri ng the t(1) domain, either magnetic field gradients or e-switching tec hniques, were used to minimize radiation damping effects. Nevertheless , a myriad of MQ artifacts, in excess of Delta m = +/- 20, were observ ed in the indirectly detected t(1) domain. The source of these MQ-like artifacts has been traced, rather surprisingly, to radiation damping in the t(2) domain. This conclusion was reached experimentally, using e-switching experiments in both the t(1) and t(2) domains, and confirm ed theoretically, using a modification of the radiation damping theory of Vlassenbroek et al., J. Chem. Phys. 103 (1995) 5886.