High-powered proton-decoupling effect spectra

Fig. 8.3. The effect of high-powered proton decoupling is shown for the C spectra at — 180°C of the central carbon of the im-butyl cation prepared from [2- C]2-chloro-2-methylpropane and SbFs. Spectrum a was obtained without decoupling and spectrum b was obtained with strong (43 kHz) H and decoupling. (Reproduced from Ref [10]. 1982 American Chemical Society.)...

The spin-lattice relaxation time for in solids is very long (several minutes). Since the nuclei have to relax before another excitation pulse can be sent, this requires hours of instrument time in order to collect a spectrum of reasonable intensity. A pulse technique called cross-polarization can be used to reduce this effect by having the protons interact with the carbon nuclei, causing them to relax more rapidly. FTNMR systems for sohd samples include the hardware and software to produce narrow line spectra from solid samples in a reasonable amount of time using high-power dipolar decoupling, MAS, and cross-polarization. 

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