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.
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)
.