University of Ottawa NMR Facility Web Site

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Friday, April 8, 2011

QCPMG for 2H NMR

QCPMG has made a tremendous impact on the field of solid state NMR in that it has enabled the collection of data for very broad resonances for unreceptive nuclei. This technique is based on the collection of a train of echoes, the Fourier transform of which produces a "spikelet" spectrum whose intensity envelope mimics the static line shape. The figure below compares the 2H quadrupolar echo spectrum and the QCPMG spectrum of perdeuterated poly-methyl methacrylate. The spectrum contains two overlapping powder patterns; a narrow one from the rotating methyl groups (QCC ~ 56 kHz) and a much less intense broad one from the rigid methlyene deuterons (QCC ~ 170 kHz). It is clear from the figure that the envelope of spikelets in the QCPMG spectrum reproduces quite well the lineshape in the quadrupolar echo spectrum.

2 comments:

Fred said...

For a spin-1 nucleus did you use 90° pulses to produce the echoes as opposed to 180° pulses in the more common qcpmg experiment?

Glenn Facey said...

Fred,

Thank you for the question. Yes, 90 degree pulses were used to produce the echoes.

Glenn