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2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT
2.5.2
Notes of Cross Polarization
Since signal intensity depends on the contact time in the CPMAS method, it is necessary
to search for the optimum conditions (
Moreover, the cross-polarization condition under high-speed MAS depends on the spin-
ning speed. The Hartmann-Hahn condition, taking into account the spinning speed ω un-
der high- speed MAS, is as follows.
| γ
I
B
Thus, since the cross-polarization condition under high-speed spinning differs from the
cross-polarization condition under low-speed spinning, it is necessary to take care during
CPMAS measurement under high-speed spinning.
2-6
| = | γ
| + n ・ ω
I
S
B
S
1
1
r
Sect. 4.3).
（ n = ± 1, ± 2 ）
NMECAXS_V50-SLD-2
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