th  - 1987 - 51st ENC Conference

MK43
MjECHANIStCSOFCOHEREHCETRANSFER IN LIQUIDS:
=ANTIPHASEmARD "IMPBASE" TRANSFER
Renzo Bazzo, Jonathan Boyd, Nick $offe
Department of Biochemistry, University of Oxford
Oxford, ENGLAND
Many NNR experiments, both 1 and 2 dimensional, rely on a
common mechanism of coherence transfer, between weak]y coupled
nut]el, which is referred to as the "antiphase" mechanism.
Free evolution can be described as a continuous exchange
between inphase and anciphase terms; whereas pu]ses (usual]y
assumed to be non-selective) cause coherence transfer of
antiphase terms or give rise to multiple quantum coherences. A
simple geometrical model will be presented which is useful to
represent the above processes.
Cross polarization experiments, introduced for liquids by
Braunschweiler and Ernst and further developed by 8ax and Davis
can give rise to "inphase" or net coherence transfer. We shall
present an analysis of the coherence transfer mechanism
involved in this class of experiments.
The cross polarization experiment will be compared with
other two-dimensional correlation techniques which rely
completely upon the antiphase mechanism. The two mechanisms of
coherence transfer will be contrasted.