5 MULTINUCLEAR MEASUREMENT
NMECAXS_V50-SLD-2
5-1
5.1 OUTLINE OF MULTINUCLEAR MEASUREMENT
The solid high-resolution NMR measurement method of rare spin systems (
13
C,
15
N,
29
Si,
31
P,
113
Cd, and others) of nuclear spins 1/2 is widely used for the structural analysis of
materials. Especially, the
13
C nucleus is
an indispensable nucleus to analyze the poly-
meric material, and various measurement techniques have been developed. On the other
hand, in nuclei with nuclear spin greater than one half, it is difficult to obtain the chemi-
cal shift because of the quadrupole interaction.
Although some nuclei such as
1
H and
19
F have nuclear spins of 1/2, they are difficult to
measure using the solid-state NMR method. The reasons for the difficulty in handling
these nuclei in the solid state are high natural abundance (100%) and a large gyromag-
netic ratio. A large gyromagnetic ratio means a strong magnetic dipole interaction, and a
high natural abundance means that the observation spins have complex interactions with
each other. Therefore, it is difficult to measure high-resolution spectra of these nuclei in
the solid state. In solution NMR, a large gyromagnetic ratio and a high natural abundance
mean a high detection sensitivity. Therefore, such characteristics are desired for the solu-
tion NMR measurement, but it is not desired for the solid-state NMR measurement.
These nuclei are called “abundant-spin system.”
In this chapter, nuclei for measurement are classified according to how they correspond to
the technique of the solid high resolution NMR measurement, and each measuring
method is explained (see Table. 5.1).
Table. 5.1 Classification of High-Resolution Techniques
Classification
Typical nucleus
Spin number
Technique of high resolution
Rare spin
13
C,
29
Si,
15
N
1/2
MAS, Heteronuclear decoupling
Abundant spin
1
H,
19
F
1/2
High speed MAS, CRAMPS
I = 1,
η
≅
0
2
H,
6
Li 1
MAS
Half integer spin
11
B,
23
Na,
27
Al (2n+1)/2
DOR,
DAS,
MQ-MAS
