6.1 XPOLAR—Cross-Polarization, UNITY
01-999162-00 C0402
VNMR 6.1C User Guide: Solid-State NMR
84
obtained just as with any other text file. The graphical display of the data can be viewed on
screen by using the command
exp1
or plotted with the command
pexp1
.
Measurement of the
1
H
T
1
through Cross-Polarization
Proton T
1
can be measured using the XPOLAR pulse sequence by performing a standard
inversion-recovery experiment on the protons followed by cross-polarization of the
remaining
1
H magnetization to the carbons.
is a diagram of the pulse sequence.
The
xpolar
macro sets up parameters for the XPOLAR pulse sequence.
Parameters
xpol
is set to
'n'
for direct polarization or set to
'y'
for cross-polarization.
pw
is the observe pulse for direct polarization or the proton 90
°
pulse for cross-polarization.
pw
is in microseconds.
p1
is the initial observe pulse (direct polarization), usually set to a 180°
°
inversion pulse,
or the initial proton pulse, usually set to a 180
°
pulse (cross polarization).
p1
is in
microseconds.
p2
is the cross-polarization contact time, in microseconds.
p3
is a pulse, in microseconds, for an X-nucleus only spin-lock following
p2
.
dm
should be set to
'nny'
. The decoupler has a maximum duty cycle of 20%.
d2
is delay between
p1
and
pw
(for inversion-recovery) if
pdp='n'
. If
pdp='y'
,
d2
is
a delay for interrupted decoupling for protonated carbon suppression.
d2
is in seconds.
srate
is the sample spinning rate, in Hz.
toss
set to
'y'
invokes timed spin-echoes to suppress spinning side bands.
level1
controls decoupler power during cross-polarization.
level1f
controls fine decoupler power during cross-polarization.
level2
controls decoupler power during acquisition.
level2f
controls fine decoupler power during acquisition time.
level1
and
level2
control decoupler power and should be used for Hartmann-Hahn
matching. The decoupler is set with the
config
display and can be either class C, with a
Figure 33. Pulse Sequence for Measuring
l
H T
1
13
C
xpol='y'
1H
p2
d1
p1
d2
pw
level1
level2