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Pulse Sequences

Hahn-Echo

The broad lines typically observed in solids NMR have rapidly decaying free induction decays which are often incompletely recorded due to a delay for probe ringing. This delay can lead to a significant part of the FID not being recorded resulting in not just the loss of signal intensity but spectral distortion as well. This problem can be overcome with the Hahn-echo pulse sequence which, much like the solid-echo pulse sequence, refocuses the transverse magnetization.


spectra 3Both experiments were performed with the 3.2 mm MAS probe. With very short rf-pulses available on the 900 very broad static lineshapes can be correclty recorded. In this case a solid-state 90-pulse for 55Mn was 0.6 us.

November, 2005




spectra 3Quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) pulse sequence dramatically improves signal-to-noise in solid-state NMR experiments of quadrupolar nuclei, here for 87Rb (I=3/2).


October, 2005