Neutron Scattering

Figure 11 .9 : S(Q, t)IS(Q) of a 2 .5 % polymer solution with a fit to the Zimm model that
theoretically describes S(Q, t) for a dilute polymer solution . The data have been measured
using the area detector at only two angular positions of the secondary spectrometer arm
within 8 h time . The hollow symbols have been obtained at an arm setting of Q = 0.05À-1
and correspond to Q/Â -1 = 0 .038, 0 .05, 0 .061, 0.072 . The filled symbols were measured
at Q = 0 .08 .1 -1 and correspond to QIÀ -1 = 0 .067, 0 .08, 0 .09, 0.102 .
relaxation functions are measured in the time demain directly and resolution correction
consists of a division instead a deconvolution in the frequency space .
One vert' important field for NSE investigations are "soft matter" problems. These comprise
polymer melts and solutions and other complex fluids . The NSE methods opens a
dynamics window in the SANS scattering vector regime . Since in that regime the dynamics
is determined by the balance between elastic (entropic) forces and friction and
in comparison inertial forces are negligible the observed fluctuations are pure relaxations
and well suited for investigation by NSE .