6.5 MASEXCH1—Phase-Sensitive Rotor Sync Sequence for Exchange
01-999162-00 C0402 VNMR 6.1C User Guide: Solid-State NMR
90
cp90 is the
13
C 90° pulse, in microseconds.
mix is the mixing time, in seconds.
sync is set to 'y' to run rotor with sync; sync is set to 'n' to run unsynchronized
(normal NOESY).
Technique
The minimum phase cycle is 16 transients and the full cycle is 64 transients.
The synched experiment requires SSBs to be present, so the spin rate should be slow
enough.
Because the mix time is recalculated on the basis of the number of integral rotor periods
that is nearest to the desired mix time, mix will not be exactly correct. The correct value is
calculated and printed at go time.
Normally, the sync experiment is run as a P-type experiment. Process the data with sinebell
weighting, wft2d('ptype') and foldt.
References
Szeverenyi, N. M.; Sullivan, M. J.; Maciel, G. E. J. Magn. Res. 1982, 47, 462.
DeJong, A. F.; Ketgens, A. P. M.; Veeman, W. S. Chem. Phys. Lett. 1984, 109, 337.
6.5 MASEXCH1—Phase-Sensitive Rotor Sync Sequence for
Exchange
MASEXCH1 is a rotor-synchronized CP/MAS exchange sequence similar to
XNOESYSYNC, except that this sequence can yield a phase-sensitive spectrum rather than
an absolute-value plot. This experiment should be run under slow spinning conditions since
spinning sidebands intensities carry the information. A normal MAS spectrum, including
sidebands, is obtained along the diagonal. Cross-peaks appear when solid-state chemical
exchange or molecular reorientation is present. Figure 37 is a diagram of the sequence.
Applicability
MASEXCH1 is available on
UNITY
INOVA and UNITYplus and present in userlib. It
requires a rotor-synchronization accessory. Rotor-speed control is also recommended. On
request, a related sequence C13EXCH is available for older systems.
Macro
The macro masexch1 converts a parameter set obtained with XPOLAR or XPOLAR1 for
the MASEXCH1 experiment. Power levels and pulse widths are retained. The default is
phase=1,2,3,4 and the data are transformed with wft2d(1,0,0,1,1,0,0,-
1,0,-1,1,0,0,1,1,0).
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