4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS
NMECAXS_V50-SLD-2
4-1
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.
