
165
only by synthesized as polycrystalline samples, and thus all the
directional information is lost. While the formalism described in
Section 6.2 is still valid, for the isotropic aggregate the experimental
parameter is now |Q| and not vector Q:
S(Q, E, T) = g(Q, E¢)F (E, E¢, T).
(6.15)
where
gQEfeMEE
d
Wi
d
j
d
d
j
dd
(, )()()()
()
/
,
¢
=◊
È
Î
˘
˚
¢
-
-+◊
-
Â
QQq
QQr
Q
12
2
d
(6.16)
FEET
E
nETEEnET EE(, ,)
'
((,) )( ') (,)( ')
¢
=◊<>+-+< >+
[]
1
1 dd
(6.17)
and ·ºÒ denotes the sampling over both the sphere of radius Q and
the phonon modes j.
species become equal in amplitude, collinear, and parallel ...