Long-range density fluctuations in orthoterphenyl as studied by means of ultrasmall-angle x-ray scattering.
The structure factor of a fragile glass-forming liquid orthoterphenyl was measured in the previously inaccessible intermediate q range between the conventional light scattering (LS) and small-angle x-ray scattering (SAXS) q ranges using the low-angle scattering beam line at the European Synchrotron Radiation Facility. At low q the structure factor exhibits an excess scattering and matches well the LS data. This excess scattering is due to long-range density fluctuations also observed in the isotropic component of scattered light. At high q the structure factor decays to a plateau corresponding to the isothermal compressibility in agreement with the conventional SAXS data. In the intermediate q range, the structure factor exhibits a power law q dependence which indicates that the excess scattering is due to fractal aggregates of denser domains.
Patkowski
A
A
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Thurn-Albrecht
T
T
Banachowicz
E
E
Steffen
W
W
Bösecke
P
P
Narayanan
T
T
Fischer
E W
EW