th  - 1987 - 51st ENC Conference

WK24
BROADBAND HETERONUCLEAR DECOUPLING
IN THE PRESENCE OF HOMONUCLEAR INTERACTIONS
D. Surer*, K.V. Schenker and A. Pines
University of California, Berkeley
Heteronuclear decoupllng in anlsotropic systems llke solids and liquid
crystals has to compete not only with the offset from resonance of the
radio frequency and the heteronuclear couplings, but also with strong
homonuclear interactions like homonuclear dipole-dipole couplings or
quadrupolar interactions. These additional interactions make the
decoupling performance of CW decoupling strongly offset dependent and
are not overcome by the composite pulse decoupling sequences developped
for isotropic liquids. We have developped a theoretical analysis of
decoupling in such systems and found a class of composite pulse
decoupling sequences designed for use in anisotropic systems that are
relatively insensitive to resonance offset and pulse imperfections. One
of the sequences, COMARO-2, can be written as YX YX YX YX YX ~, where
each element represents a composite pulse 385 320 25.
sl
/ _\
lg
• -" .-•'"
Figure : Left : theoretical offset dependence of deuterium decoupling
for a single deuteron. Right : experimental results from
dimethoxybenzene-d 8 in a nematic liquid crystal.
References :
D. Suter, K.V. Schenker and A. Pines, J. Magn. Reson. (Hay 1987).
K.V. Schenker, D. Surer and A. Pines, J. Magn. Reson. (Hay 1987).
CW
2