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Pulse Sequences

STMAS

Similar to the MQMAS pulse sequence STMAS is a 2D experiment that correlates a satellite transition with the central transition of half-integer quadrupolar nuclei. The technique is useful when signal intensity is poor or multiple sites of widely varying quadrupolar coupling constants exist. The 2D spectrum reveals an isotropic projection in f1 and the central transitions powder pattern in f2. Application of this pulse sequence is advantageous in that only single quantum coherences are used, as opposed to the analogous MQMAS sequence, and there is a potential for signal-to-noise enhancement. However, the sequence is extremely sensitive to the setting of the magic angle and can suffer from poor resolution if several satellite transitions are excited.

 

spectra 3

Similar to MQMAS, satellite transition MAS of half-integer quadrupole nuclei (STMAS) can be used to separate anisotropic from isotropic interactions. Experiments performed by S. Steuernagel (Bruker) with the 2.5 mm MAS probe.


July, 2006