Symmetry Principles for the design of radiofrequency
pulse sequences in the nuclear magnetic resonance of
rotating solids,
M. Carravetta, M. Edén, X. Zhao,
A. Brinkmann, and
M. H. Levitt,
Chem. Phys. Lett.
321,
205215,
(2000).
Full text (PDF)
Some new symmetry theorems are presented which simplify the task of
designing multiplepulse radiofrequency pulse sequences in
magicanglespinning solidstate NMR. The symmetry theorems
apply to sequences denoted RN_{n}^{ν},
where N, n and ν are integral symmetry numbers.
A RN_{n}^{ν}
sequence consists of N repetitions of a pulse sequence element R,
alternating in phase between the values ±πν/N.
Each R element ideally rotates the spins by an angle π about the rotating frame
xaxis. The entire RN_{n}^{ν} sequence is timed
to span n rotational periods. The symmetry theorems allow the construction of
sequences suitable for a wide range of purposes in solidstate NMR. Specific
applications are presented for homonuclear doublequantum recoupling, heteronuclear
decoupling and heteronuclear recoupling. For the case of homonuclear doublequantum
recoupling, we demonstrate a highperformance sequence with the symmetry
R14_{2}^{6}. For the case of heteronuclear decoupling, we show
that the existing theory provides a framework for understanding the operation of
the twopulse phase modulation (TPPM) scheme (A. E. Bennett, C. M. Rienstra, M. Auger,
K. V. Lakshmi and R. G. Griffin, J. Chem. Phys. 103, 6951 (1998)).
We also demonstrate a heteronuclear dipolar recoupling sequence with the
symmetry R18_{1}^{7}.
