Free induction decay broad-line spectrum

The corrected free induction decay Sc t) will transform to a spectrum Sc i ) in which not only the acetone signal but also all the ethanol signals have had the instrumental contributions to their lineshapes removed. Provided that the reference region lui to wr gives a complete and accurate representation of the experimental acetone lineshape, our deconvolution process should allow us to obtain a clean corrected spectrum even when the shimming is far from ideal. There are of course limitations on this process. If the experimental lineshape is very broad, it will clearly not be possible to obtain a corrected spectrum in which the lines are very narrow without some sort of penalty. Here the limiting factor is signal-to-noise ratio since S u>) is much sharper than Se u>), the ratio of their inverse Fourier... 

Rg. 5. H NMR spectrum from a Fourier transform of the free induction decay at 92 MHz and 1.43 K in one of the annealed samples showing (a) the broad and narrow central lines and (b) the molecular H2 powder pattern with broadened singularities at (88 5) kHz. 

From H pulse NMR, the free induction decay (FID) with a large number of data points can be obtained. The curve fitting for the observed FIDs gives the individual T2 characteristics in the crystalline, amorphous, and interfacial phases [6-12]. Such a resolution into several components has been attempted on a broad-line spectrum of solid polyethylene (PE) [13-16], which reflect the sample morphologies. 

Figure 1 NMR spectrum of a guinea-pig heart perfused with Krebs-Henseleit solution. The spectrum was acquired at 8.7 T using a broad-band probe tuned to 145.8 MHz. Peak assignments are 1, phenylphosphonic acid (external reference) 2, phosphomonoesters 3, inorganic phosphate (P ) 4, phosphocre-atine (PCr) 5, y-phosphorus of adenosine triphosphate (ATP) 6, a-phosphorus of ATP 7, 5-phosphorus of ATP. The spectrum was acquired in 2.5 min by summing 72 free induction decays (FIDs) with a 35 gs pulse and a repetition time of 2 s. Prior to Fourier transformation the FID was subjected to exponential multiplication with a 20 Hz line broadening factor.

---