NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...

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CHAPTER 6
" MEASUREMENTS ON THE SPIN-LATTICE RELAXATION TIMES
6.1 INTRODUCTION
IN THE CUPROUS
HALIDES
The work described in this chapter deals with T1 measurements
on samples of the three solid cuprous halides. Interest in these
compounds first arose from their use as reference samples in the
accurate measurement of the Knight shift of 63Cu and 65Cu
in metal-
lic copper by the macroscopic rotation technique(67). Accurate
values of their chemical shifts were obtained at the same time (77)
It was decided to extend the investigation of these compounds to
the measurement of their spin-lattice relaxation times.
The cuprous halides have a zinc blende structure, the copper
and halogen atoms lying on separate FCC sites displaced from each
other by one-quarter of the distance along the body diagonal. Hence
each atom is surrounded tetrahedrally by four atoms of the opposite
kind. Despite the lack of any secular quadrupole interaction in
crystals having cubic symmetry, time dependent quadrupole interact-
ions arise from the distortion of the nuclear symmetry by lattice
phonons. The nuclear spin relaxation mechanism generated by the
lattice vibrational modes proves to be dominant over a large temper-
ature range in these compounds.