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Accueil > Publications > Archives 2004-2010 > 2010

Dynamics and rheology under continuous shear flow studied by x-ray photon correlation spectroscopy

par Salmon Jean-Baptiste - publié le

X-ray photon correlation spectroscopy (XPCS) has emerged as
a unique technique allowing the measurement of dynamics of materials on
mesoscopic lengthscales. One of the most common problems associated with
the use of bright x-ray beams is beam-induced radiation damage, and this
is likely to become an even more limiting factor at future synchrotron and
free-electron laser sources. Flowing the sample during data acquisition is
one of the simplest methods allowing the radiation damage to be limited. In
addition to distributing the dose over many different scatterers, the method
also enables new functionalities such as time-resolved studies. Here, we further
develop a recently proposed experimental technique that combines XPCS and
continuously flowing samples. More specifically, we use a model colloidal
suspension to show how the macroscopic advective response to flow and the
microscopic dissipative dynamics (diffusion) can be quantified from the x-ray
data. Our results show very good quantitative agreement with a Poisseuille-flow
hydrodynamical model combined with Brownian mechanics. The method has
many potential applications, e.g. in the study of dynamics of glasses and gels
under continuous shear/flow, protein aggregation processes and the interplay
between dynamics and rheology in complex fluids.