Open AccessX‐ray photon correlation spectroscopy under flow
Author(s) -
Fluerasu Andrei,
Moussaïd Abdellatif,
Falus Péter,
Gleyzolle Henri,
Madsen Anders
Publication year - 2008
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049508006420
Subject(s) - brownian motion , flow (mathematics) , scattering , dynamic light scattering , relaxation (psychology) , shear flow , spectroscopy , diffusion , physics , transverse plane , materials science , molecular physics , optics , mechanics , nanoparticle , nanotechnology , thermodynamics , psychology , social psychology , structural engineering , engineering , quantum mechanics
X‐ray photon correlation spectroscopy was used to probe the diffusive dynamics of colloidal particles in a shear flow. Combining X‐ray techniques with microfluidics is an experimental strategy that reduces the risk of X‐ray‐induced beam damage and also allows time‐resolved studies of processes taking place in flow cells. The experimental results and theoretical predictions presented here show that in the low shear limit for a `transverse flow' scattering geometry (scattering wavevector q perpendicular to the direction of flow) the measured relaxation times are independent of the flow rate and determined only by the diffusive motion of the particles. This is not generally valid and, in particular, for a `longitudinal flow' ( q ∥ flow) scattering geometry the relaxation times are strongly affected by the flow‐induced motion of the particles. The results here show that the Brownian diffusion of colloidal particles can be measured in a flowing sample and that, up to flux limitations, the experimental conditions under which this is possible are easier to achieve at higher values of q .