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3 SETTING OF INSTRUMENT CONDITIONS
3.7
ADJUSTMENT OF CROSS-POLARIZATION CONDI-
TIONS
Adjustment of CP（Cross-Polarization） conditions is performed to satisfy the Hart-
mann-Hahn conditions. The Hartmann-Hahn conditions are different between low- speed
spinning and high-speed spinning. Therefore, you need to adjust the conditions according
to the spinning speed.
In this section, adjustment of CP conditions is explained for a spin 1/2 nucleus.
3.7.1
Adjustment of Cross-Polarization Condition under
Low-speed Spinning
The Hartmann-Hahn condition under low-speed spinning is the following equation.
γ
B
I
I
Under actual work conditions, set the values of irr_amp_cp and obs_amp_cp so that the
90° pulse width for the observation nucleus equals the 90° pulse width for the irradiation
nucleus.
1.
Set the standard sample (such as, adamantane).
2.
Perform spinning at 5 kHz.
3.
Load the pulse sequence cpmas.jxp into Experiment Tool.
4.
Set scans to a multiple of 2.
5.
Set obs_shape_cp to constant_cp.
6.
Set irr_amp_cp value of Proton.
7.
Set the array measurement for obs_amp_cp of Carbon13.
8.
Click the Submit button.
The pulses occur, and the measurement starts.
If the measurement ends, the nD Processor window automatically opens.
9.
Perform the data processing.
After data processing, the result is displayed by selecting Linearize.
10.
Examine the optimum obs_amp_cp value.
In the spectra for which you carried out the Linearize processing, the value of
obs_amp_cp with the strongest signal intensity is the optimum value for
cross-polarization conditions.
Under high-speed spinning, two or more obs_amp_cp with strong signal intensities
exist. In this case, refer to the adjustment of CP conditions under high-speed spin-
ning (
3-10
= γ
B
S
S
Refer to the user's manual "Data processing" for processing the data obtained
by the array measurement.
Section 3.7.2).
NMECAXS_V50-SLD-2
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