DPFGSE spin-echo

Figure 4 Methods of selectivity enhancement using pulsed field gradients employing (a) selective excitation pulses, (b) a selective refocusing pulse and (c) a double piUsed field gradient spin echo (DPFGSE) sequence with inversion pulses...

The double pulsed field gradient spin echo (DPFGSE) pulse sequence has been used to improve the measurement of proton-proton nuclear Overhauser effect (NOE) [28]. The DPFGSE NOE does not rely on difference spectroscopy and very small NOEs can be measured. This technique has been used to determine the structure of organosilicon compounds [28]. 

Figure 6-41 The double pulse field gradient spin echo (DPFGSE) NOE experiment with llp-hydroxyproges-terone (a) the unirradiated spectrum (b)-(g) spectra with irradiation at selected frequencies. (Reproduced with permission from K. Stott,...

The most robust experiment to date [34] (Fig. 8.39b) is based upon the double pulsed field gradient spin-echo (DPFGSE) sequence as a means of selecting a target resonance from which the NOEs ultimately develop. This... 

Matrix representation of the effect of a single (SPFGE) and double pulsed field gradient spin echo (DPFGSE). 

DPFGSE Double Pulsed Field Gradient Spin Echo... 

The traditional nuclear Overhauser difference spectroscopy can be replaced by DPFGSE-NOE (Double Pulsed Field Gradient Spin Echo method-NOE spectrometry) experiment. The desired NOE effects can be recorded without interference from other signals and without phase distortion [66]. 

Fig. 8.33 Pulse sequence schematic for the gradient ID NOESY experiment. The double pulsed field gradient spin echo (DPFGSE) refocuses only for that resonance subject to the selective pulse. All other magnetization is left defocused in the xy-plane. Ultimately, a NOESY spectrum is recorded only for the selected re-...

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