Pulse sequence selective spin-flip method

There are several types of heteronuclear 2D J-resolved experiments (i) the gated decoupler method, (ii) the spin-flip method, (iii) the selective spin-flip method, (iv) the semi-selective spin-flip method, and (v) the use of polarization transfer, e.g., INEPT. In all these experiments, the pulse sequence results in the generation of spin echoes which are modulated during the evolution period by coupling frequencies. 

Figure 5.45. (A) The selective spin-flip method for recording heteronuclear 2D J-resolved spectra in which the signals are modulated by long-range coupling constants. The pulse sequence is shown above while its effect on the magnetization vectors is shown below it. The selective 180° pulse results in elimination of the large one-bond coupling constants, Jch ( ) j -Methylcellobioside with the torsional angles (j) and ij/ indicated.

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