FT-NMR spectrum

Figure 1.7. Pulse interferogram and FT NMR spectrum of glycerol, DOCH2)2CHOD, [020, 25 °C, 100 MHz]...

Spin-spin relaxation is the steady decay of transverse magnetisation (phase coherence of nuclear spins) produced by the NMR excitation where there is perfect homogeneity of the magnetic field. It is evident in the shape of the FID (/fee induction decay), as the exponential decay to zero of the transverse magnetisation produced in the pulsed NMR experiment. The Fourier transformation of the FID signal (time domain) gives the FT NMR spectrum (frequency domain, Fig. 1.7). 

FID Free induction decay, decay of the induction (transverse magnetisation) back to equilibrium (transverse magnetisation zero) due to spin-spin relaxation, following excitation of a nuclear spin by a radio frequency pulse, in a way which is free from the influence of the radiofrequency field this signal (time-domain) is Fourier-transformed to the FT NMR spectrum (frequency domain)... 

If Ha and H6 are trans to each other, and Hc and are tram to each other, we say the configuration is trans-trans. The natural-abundance C13 FT NMR spectrum with protons decoupled shows 12 lines. How many lines would occur for each of the following configurations (a) trans-trans (b) cis-trans (c) cis-cis. 

Preparation, evolution and detection are the time periods of pulse sequences described for. /-modulated spin-echo and polarization transfer experiments. The basic FT NMR technique operates without any evolution period tt immediately after generation of transverse magnetization (preparation) its free induction decay S(t2) is detected. Subsequent Fourier transformation provides the FT NMR spectrum S (f5). 

Figure 4. Effect of pH on the 31P FT-NMR spectrum of inositol hexaphosphate in a concentrated humic-FeEDTA matrix.

Figure 12. 31P FT-NMR spectrum of Crystal Lake sample G, 1000-dalton membrane retentate fraction, before and after alkaline bromination. The total soluble phosphorus concentration was 50 mg of P/L.

Berberis empetrifolia yielded the unstable base coyhaiquinine (471), C26H25N05. The structure was proposed principally from the completely resolved 200-MHz FT NMR spectrum, and the alkaloid was shown to have syn geometiy at the spiro center by NMR correlations with the related syn compounds 46,107,149,262, and 359 and with the anti alkaloids 108 and 109. Insufficient material was available for exact determination of optical rotation, but the general form of the CD curve resembles that of coyhaiquine (107), indicating the absolute configuration shown (554). 

Dihydrogen can be cooled into a liquid and then a solid phase. Thus solid-state proton NMR is feasible, including single-crystal work. The gas-phase (200 torr, room T) XH FT-NMR spectrum at 200 MHz exhibits a single line. 4... 

Figure 5. FT NMR spectrum of Amax Fraction 30 in d-chloroform with hexamethyldidloxane reference...

FT NMR spectrum of Monterey Fraction form loith hexamethyldisiloxane reference... 

Figure 10. FT NMR spectrum of a portion of Amax Fraction 10 (tubes 38—42, see Figure 3) in d-chloroform with nexamethyldisiloxane...

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