Figure 9.41
(a) Single decaying sine wave and a plot of the single
frequency it represents.
(b) two decaying sine waves and a plot of the two
frequencies they represent.
(c) Many co-added sine waves in a free induction
decay of the^13 C NMR spectrum of 3-ethylpyridine^
and the frequency domain spectrum they represent.resonance peaks (Figure 9.41(b)) arise from a more complex sinusoidal FID signal whilst the complete
(^13) C spectrum shown in figure 9.41(c) is derived from an FID signal which is far too complex to be
understood by visual inspection and can be unravelled only by computer processing. The complexity of
such FID signals is due to the superimposition of and mutual interference between the decay signals
from all excited nuclei.