Magic-angle hopping

An important advantage of the GRASSHopper device is the fact that after a complete MAH cycle of three orientations, the MAH device can be re-initialized by rotating backward to the initial orientation. For this reason, a number of flexible input and output lines to the sample chamber of the GRASSHopper device exist and allow a rotation of the fixed-bed reactor about an axis in the magic-angle while the system is gas-tight (Fig. 16). In the reported experiments 66), the 120° hop time... 

Jian Zhi, Hu and R. Pugmire, Magic angle turning and hopping, in The Encyclopedia of NMR, Wiley, Chichester, 1996. 

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