Bruker BioSpin Solid State NMR, User Manual

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User Manual Version 002 BRUKER BIOSPIN 169 (327)
13
SUPER 13
Overview 13.1
S eparation of U ndistorted Chemical-Shift Anisotropy P owder patterns by E ffort-
less R ecoupling (SUPER) correlates CSA powder patterns in the F1 dimension
with the isotropic chemical shift in the F2 dimension. The SUPER experiment is
based on Tycko’s CS – CSA correlation experiment, but provides better compen-
sation for experimental imperfections such as B
1
in-homogeneities and pulse im-
perfections. Also, both experiments produce scaled powder patterns in F1, and
the scaling factor is more favorable in SUPER than the factor 0.39 in Tycko’s ver-
sion. As a consequence, the SUPER experiment does not require high spinning
speeds (to fit the F1 lineshape into the rotor-synchronized spectral window) or
very strong
13
C pulses.
SUPER has several advantages. First of all, it covers a large bandwidth for the
isotropic chemical shift. Secondly, no requirements exist for
1
H decoupling during
the recoupling pulses, because it uses 360º pulses instead of the 180× pulses in
Tycko’s experiment. Exact 360º pulses automatically decouple the heteronuclear
dipolar interaction so that no or only weak
1
H decoupling is required during the re-
coupling pulses. The scaling factor is normally 0.155 so that a spectral width over
40 kHz can be achieved in the indirect dimension. As a consequence, moderate
spinning speeds of up to 6.5 kHz can be chosen so that experiments can be per-
formed without serious problems on high field instruments. The limiting factor in
the choice of the spinning speed is the rotor synchronization requirement of the
recoupling 360º pulses:
References:
1. S-F. Liu, J-D Mao, and K. Schmidt-Rohr, A Robust Technique for Two-Dimensional Separation of Un-
distorted Chemical-Shift Anisotropy Powder Patterns in Magic-Angle-Spinning NMR , J. Magn. Reson.
155, 15-28 (2002).
2. R. Tycko, G. Dabbagh, and P.A. Mirau, Determination of Chemical-Shift-Anisotropy Lineshapes in a
Two-Dimensional Magic-Angle-Spinning NMR Experiment , J. Magn. Reson. 85, 265-274 (1989).
rot RF
ν ν
12 . 12
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