title: Nanoscale NMR velocimetry by means of slowly diffusing tracer particles.
abstract: The resolution of NMR velocimetry is inherently limited by random displacements due to molecular self-diffusion, and has so far not extended below a few tens of microns. We report here an extension to the nanoscale domain, a result achieved by the use of slowly diffusing, NMR-visible core-shell latex particles. These particles comprise an oil core surrounded by a solid polymer shell, making spheres of diameter 370 nm. Using these particles in the annulus of a concentric cylinder Couette cell, we have measured flow-induced displacements down to a few hundreds of nanometers, allowing the observation of the solid-to-liquid transition of a glassy system. We envisage new possibilities for NMR velocimetry as an experimental tool for colloidal chemistry and physics.
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand. hewa@surfchem.chalmers.se
authors.forename: Helena
authors.initials: H
authors.lastname: Wassenius
authors.forename: Paul T
authors.initials: PT
authors.lastname: Callaghan