Research objectives and content
In this project we will investigate the dynamics and structural rearrangements of glassy colloidal suspensions subjected to a periodic shear strain. The motion of the colloidal particles will be studied for low oscillatory shear strains, where an elastic response of the suspension is expected, as well as for high shear strains, where the suspension is expected to yield. The question of the reversibility of the colloidal motion, and thus the degree of rearrangement of the suspension below and above the yield stress, will be addressed. Probing the colloidal motion under these conditions will enhance our understanding of the mechanisms of yielding in such amorphous systems.
The main experimental technique to be employed is Diffusing Wave Spectroscopy (DWS) which, in highly turbid samples, can probe much more local scale dynamics than conventional Dynamic Light Scattering (DLS). DWS will be used to probe the motion of the particles induced by the strain and to detect the reversibility of the motion through echoes in the intensity correlation function of multiply scattered light (see, e.g., Hebraud et al., Phys. Rev. Lett. 78, 4657, 1997). As supplementary techniques we will use DLS under oscillatory shear strain for single scattering systems, as well as Two Colour Dynamic Ligh Scattering (TCDLS) and DWS of quiescent multiply scattering colloidal suspensions.
Training content (objective, benefit and expected impact)
Training will be received in the properties of colloidal systems and in several specialized and modern light scattering methods. As part of a large group pursuing theory and simulation as well as experiment, the applicant will also be exposed a broad range of other topics in the general area of soft condensed matter. As noted under 'Description of the Host Institution', he will have access to all the resources of a large group in a well-established department.
Links with industry / industrial relevance (22)
The Edinburgh soft condensed matter group has strong linlcs with industry - see 'Description of the Host Institution'