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4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS
4.1
SETTING PULSE WIDTH IN SINGLE PULSE
MEASUREMENT
Usually, the flip angle obs_angle_prep is set to 90 deg for a solid-state NMR measure-
ment. However, for a sample with a very long relaxation time, making the flip angle
small shortens the waiting time of relaxation_delay.
Moreover, for nuclei with quadrupole interactions, caution is required for setting the
obs_width. In the case of nuclei with nuclear quadrupole interaction, the 90° pulse width
depends on the strength of the interaction. When the nuclear quadrupole interaction is
small, the 90° pulse width is almost the same width as that in the solution. However, as
the nuclear quadrupole interaction increases, the 90° pulse width shortens. When the nu-
clear quadrupole interaction is strong enough, the 90° pulse width becomes 1/(I+1/2)
times the 90° pulse width of the solution (I is the nuclear spins number). Therefore, for
this kind of nuclei, set obs_width to less than 1/(I+1/2) of the 90° pulse width of the so-
lution. Furthermore, when performing a quantitative measurement, it is desirable to set
the pulse width to 1/(I+1/2)/2 times the 90° pulse width of the solution or less.
NMECAXS_V50-SLD-2
4-1
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