NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...
NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...
NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...
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- 11 -<br />
If rii = nrij = (Xli + X2j + X3k) where X1X2X3 are direction<br />
cosines,<br />
then<br />
1-3X<br />
Dia = -3X1X2<br />
-3X 1a3<br />
-3X1a2<br />
-3X1X3<br />
1-3X2 -3X2X3<br />
-3X2X3<br />
1-3X3<br />
Since Xi + X2 + X3 = land D2,<br />
m = DMZ the tensor is traceless and<br />
symmetric.<br />
Similarly the truncated dipolar interaction may be represented<br />
by the traceless symmetric tensor<br />
J<br />
100<br />
Di O10 (3 cos20 - 1)<br />
d<br />
00 -2<br />
2.2.2 THE QUADRUPOLE<br />
<strong>IN</strong>TERACTION<br />
Nuclei with spin greater than I possess an electric quadrupole<br />
moment and therefore interact with electric field gradients produced<br />
by the surrounding charge distribution. Following the approach<br />
of Cohen and Reif (3)<br />
this interaction may be written in the form<br />
of a product of two second rank symmetric tensors so<br />
q=I<br />
a, ß<br />
12v<br />
(8a&ß)r=O Qaß<br />
eQ<br />
6I(2I- 1)<br />
a, ß<br />
2<br />
ýa ß)r=0l2(IaIß<br />
+ Ißla) - 6aß1(1 + 1)]<br />
where V(r)r_O is the crystalline electrostatic potential at the<br />
nucleus, aß refers to any pair of cartesian axes and Q is the<br />
quadrupole moment.<br />
(2.4)
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