3 SETTING OF INSTRUMENT CONDITIONS
3.8 ADJUSTMENT OF DECOUPLING CONDITIONS
For a sample containing
1
H, it is necessary to perform high-power decoupling (
Sect.
2.3). Since very strong RF pulses are used for high-power decoupling, it is necessary to
decrease the decoupling power in the measurements in which the data acquisition time
x_acq_time
is 100 ms or more.
3.8.1 Setting of CW (Continuous Wave) Decoupling Conditions
In the solid-state NMR, since very strong RF pulses are applied in comparison with the
solution NMR, RF power is applied only during data acquisition.
When the data acquisition time is about 100 ms or less, you can use the value of
irr_amp_dec
at 100% (the maximum power which can be used in the equipment). When
the data acquisition time is longer, you need to lower the value of
irr_amp_dec
and
measure.
3.8.2 Setting of TPPM Decoupling Conditions
In the decoupling of TPPM (Two Pulse Phase Modulation), adjust the pulse width
irr_pwidth
and phase shift value
irr_tppm_shift
.
1.
Set the standard sample glycine.
2.
Set
irr_noise
to
TPPM
.
3.
Perform the array measurement for
irr_ width_tppm
and
irr_phs_tppm
.
4.
Click the
Submit
button.
The pulses occur, and the measurement starts.
When the measurement ends, the
nD Processor
window automatically opens.
5.
Perform data processing.
Please refer to the user’s manual “Data processing” for information on proc-
essing the data obtained by the array measurement.
6.
Take
a slice of C
α
carbon
in the 3D processed spectrum.
7.
Obtain the values of
irr_ width_tppm
and
irr_phs_tppm
with the strongest
signal intensity
in the two-dimensional data of the YZ plane.
NMECAXS_V50-SLD-2
3-13
