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3.7.2
Adjustment of CP Condition under High Speed Spinning
The Hartmann-Hahn conditions, taking into consideration spinning speed ω
high-speed spinning, are as follows:
γ
B
I
I
Under actual work conditions, set the value of irr_amp_cp and obs_amp_cp so that it
satisfies the conditions for every spinning speed.
3.7.3
Adjustment of VACP Conditions
CP conditions under high-speed spinning are very sensitive to errors in the condition set-
tings. Therefore, in an actual measurement, the sensitivity decreases abruptly due to
causes such as inhomogeneity of the magnetic field. In order to compensate for such im-
perfection, the modulation is applied to the output power of the observation channel dur-
ing spin lock, thereby increasing sensitivity.
1.
Set the adamantane standard sample.
2.
Adjust spinning speed.
The slope of the VACP depends on the spinning speed.
3.
Set obs_shape_cp to RAMP_cp.
4.
Set up the irr_amp_cp value of Proton, and the obs_amp_cp value of Car-
bon13.
5.
Perform an array measurement for obs_amp_grad of Carbon13.
6.
Click the Submit button.
The pulses occur, and the measurement starts. When the measurement ends, the nD
Processor window automatically opens.
NMECAXS_V50-SLD-2
= γ
B
+ n・ ω
（n = ± 1, ± 2）
S
S
r
1
H
13
C
1
H
13
C
amp
If the VACP method is used, the contact time will become a little longer.
The slope to use in the VACP method depends on the spinning speed.
3 SETTING OF INSTRUMENT CONDITIONS
Contact Time
Decoupling
Constant CP method
Decoupling
Δamp
VACP method
under
r
3-11
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