Gradient coils pulse

The probe, situated between the field gradient coils in the bore of the magnet, consists of a cylindrical metal tube that transmits the pulses to the... 

The hardware required for PEG work, although commercially available, is not usually included in the basic version of spectrometers. It consists of a gradient accessory, a gradient amplifier, a shielded probehead equipped with a z-gradient coil and a pulse shaper (which in itself is an integral part of the gradient accessory). 

As is the case in most gradient-enhanced pulse sequences, GROESY spectra should preferably be obtained with non-spinning samples. In our spectrometer, a Bruker ARX-400 equipped with an inverse broadband probehead incorporating a shielded Z-gradient coil, we have used the following experimental parameters ... 

Fig. 1. Radio frequency (top) and magnetic field gradient (bottom) pulse sequence for the basic POSE experiment (Ref.I4>, by permission). Advances in coil current regulation have obviated the necessity of adjusting S to keep 8 - O constant.

The on-line SEC-NMR measurements were performed on a 750 MHz spectrometer with an inverse-geometry LC-NMR probe with pulsed-field gradient coils. The detection volume of the flow cell was approximately 60 pi A Shodex linear K-805L SEC column (8 mm x 300 mm) with a maximum porosity of 4 x 106 was used for the chromatography. 

For non-deuterated complexes, NMR experiments were performed on either Vaiian Unity600 or Varian Unity+500 spectrometers. The 600 MHz instrument was equipped with a triple resonance probe and a PTS synthesizer as a pseudo fourth channel. The 500 MHz spectrometer was a four channel instrument with a triple resonance probe with an actively shielded pulsed field gradient coil. All experiments were performed at 37 C. The heteronuclear experiments shown in Figure 1 were performed as described in Zhang et al (11) and Revington et al (24). For all 3D ex riments 32 transients were required for sufficient signal to noise. This necessitated the use of fewer increments and the use of linear prediction (25)... 

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