Broadband decoupling spin echo pulse sequences

The spin-echo pulse sequence can also be applied to produce homonuclear (e.g., H) J-resolved spectra. For such a system it is not possible to apply broadband decoupling, so the F2 dimension might be expected to display the ordinary coupled H spectrum. However, because the coupling information is independently available, it is not difficult to process the data in such a way that only the chemical shifts are displayed in the F2 dimension, as illustrated in Fig. 10.7. 

Figure 5.42. The 2D C, H COSY NMR spectrum of erythromycin in CDCIj as a contour plot beneath the corresponding ID C spin-echo NMR spectrum. The spin-echo spectrum (pulse sequence 90°-(r-I80°-x) -data acquisition) was acquired with broadband proton decoupling during the second period and data accumulation. With x = 8 ms CH2 and C resonances are inverted relative to CHj and CH resonances. The small triangles (A) indicate the two outer lines of the solvent triplet. The contour plot levels are higher than the cross-peaks due to methylene moieties.

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