Gated decoupler method

The most common way to record heteronuclear 2D /-resolved spectra is the gated decoupler method, so called because the decoupler is gated, i.e., switched on during the preparation period (for nOe) during the first... 

FIG. 16. A portion of the two-dimensional J-spectrum of pyridine corresponding to the C site, obtained by the "gated decoupler" method. Aliasing caused by the low sampling rate has drawn the two halves of the spectrum together by 72 Hz, From ref 153,... 

Figure 7.3. The 125 MHz H- C heteronuclear J-resolved spectrum of menthol 7.1, above which is the conventional ID carbon spectrum. The gated decoupler method of Fig. 7.1b was used and the splittings in fi are therefore half their true Jch values.

Fig. 5.14 Two variants of the 2D X J(X, H)-resolved experiment. The sequence of the left-hand side uses the "spin-flip method whilst the sequence of the right-hand side uses the "gated-decoupling" method.

Figure 9. Pulse sequence used in acquiring the spectrum of Figure 8 this "gated decoupler" method for heteronuclear 2D J spectroscopy results in the multiplet splittings in fj appearing to be halved.

Spin-lattice relaxation times (Ti) for the a-carbon region were determined by the inversion-recovery technique [19]. Nuclear Overhauser Enhancements (NOE) were measured by the gated decoupler method [20]. 

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 5.43. Gated decoupler method for recording 2D J-resolved C-NMR spectra. The upper portion shows the pulse sequence while the lower portion represents the effect of the pulse sequence on magnetization of a CH group decoupling during the preparation period provides nuclear Overhauser enhancement. The position of the two magnetization vectors in (d) will be dependent on 11 the sum of the two vectors which is detected will depend both on and the magnitude of the coupling constant, J. The signals are then said to be J-modulated. ...

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