Neutron Scattering

Equations (14 .12) and (14 .13) are determined by infra- und intermolecular interferences as
also made visible by the accompanying symbol.
14 .3 .3 . Babinet Principal
Incompressible melts show no thermal density fluctuations and therefore no diffraction can
occur in such a single type polymer melt . The scattering cross section must be zero and
following Eq. (14 .13) one therefore gets the following relationship
P(Q)=- nW(Q)
b
H
representing the Babinet principal .
14 .3 .4. Melt of deuferated and protonated polymers with chemically identical monomers
ofsame segment length .
We now discuss a blend of chemically identical polymers whose components are either
protonated or deuferated . For further theoretical consideration we introduce an occupation
operator a ; with the following meaning
1 b ; =b p
0 b ; = b
The operator is 6 ; =1 and 6 ; =0, ifthe monomer at the position i is deuterated and protonated,
respectively . The coherent scattering length of a monomer at the position i is then described
as
b i =a; (b, -bH)+bH=6;'Ob+b, (14 .16)
This expression inserted into Eq .(14 .1) gives
and fmally
N
aL 1 7QP'- N iQr 2
d22(Q)-V
s a=1 t=1 _
=s(Q)
14-8