Wideband, uniform rate, smooth truncation WURST

Siegel et al. showed that enhancement of the CT can also be obtained using hyperbolic secant (HS) pulses to invert selectively the STs [74], Unlike the DFS waveform, whose frequency sweep is generated by a constant rf-pulse phase while modulating the amplitude, the HS pulse utilizes both amplitude and phase modulation, yielding an enhancement exceeding that obtained by DFS or RAPT [61, 74, 75]. Most recently, the pulse sequence called wideband uniform-rate smooth truncation (WURST) [76] was introduced to achieve selective adiabatic inversion using a lower power of the rf-field than that required for the HS pulses [77,78]. One of its applications involved more efficient detection of insensitive nuclei, such as 33S [79]. 

Very recently, the WURST-QCPMG sequence was developed to achieve uniform excitation of quadrupolar nuclei across very wide bandwidth using frequency-sweep chirped pulses [86]. The WURST (wideband uniform-rate smooth truncation) pulses provide broadband excitation. Integrating the WURST pulses with QCPMG results in the WURST-QCPMG method, which has proven to be a highly efficient approach for acquiring ultra-wideHne NMR spectra [74]. 

WURST Wideband, uniform rate and smooth truncation (broadband decoupling sequence) 9.2... 

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