WAHUHA irradiation

Some chemical-shift spectra as a function of WAHUHA irradiation for poly(o-chlorostyrene) are shown in Figure 2. 

Protonated carbon magnetizations rapidly dephase under as little as two cycles of WAHUHA irradiation, but are refocused after sixteen cycles (one rotor period). Magic-angle spinning should refocus dipolar coupling just as it does chemical shift aniso-... 

The dipolar pattern for polystyrene shown in Figure 3 (left) is not a Pake doublet reflecting only the CH static dipolar coupling (as scaled by WAHUHA irradiation of the protons). 

In 1968, J. S. Waugh et al reported a new method for removal of the homonuclear dipolar interaction using multiple pulses (WAHUHA-4 Waugh, Huber and Haeberlen 4 pulses/cycle), which is shown in Fig. 2. Homonuclear dipolar decoupling by multiple-pulse irradiation is termed MAS in spin space . In general, we consider that the magnetization of the z direction is... 

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