(In the group of Prof. Peter Pusey, Physics Dept., Univ. of Edinburgh,

Scotland: March 1993-Aug. 1995.)

     The aim of this project was two-fold. First a new Two-Color Dynamic Light Scattering setup, delivered to us from ALV corp, was installed, aligned, and a full testing of its performance characteristics was done, see ref. [1]. The second part of the project was to use the instrument to study the dynamics of concentrated colloidal suspensions of nearly monodisperse hard spheres of PMMA, refs. [2-4]
 
    In the first part of the study, short-time Brownian motion was measured for all volume fractions up to that of the freezing transition at f=0.494, in ref. [2]. Good agreement was found between our results and those from a Lattice-Boltzmann Equation simulation of hard sphere suspensions. We then measured on the same samples both short- and long-time Brownian motion as well as the low shear rate viscosity and found a simple relation regarding viscosity and structural relaxation, in ref. [3]. Finally we found that the q-dependent measured time correlation functions f(q,t) for all volume fractions up to the glass transition exhibit a very simple scaling relation that indicates a close connection between structural relaxation and self-diffusion, see ref. [4].

    In preparation now is a more complete write up of the measured time correlation functions for all volume fractions up to that of the freezing transition at f=0.494, as well as some metastable and glassy samples...
 

References

1.    "Two-Colour Dynamic Light Scattering"
                        P.N. Segrè, W. van Megen, P.N. Pusey, K. Schatzel and W. Peters, J. Mod. Optics 42, 1929 (1995).  abstract
            4. (a)    "Multiple Scattering Suppression in Dilute and Concentrated Colloidal Dispersions"
                           P.N. Segre and P.N. Pusey, Nuovo Cimento 16, 1181 (1994). abstract
         For a pictorial description of the TCDLS story, click here.

2.    "Short-Time Brownian Motion in Colloidal Suspensions - Experiment and Simulation"
                    P.N. Segrè, O.P. Behrend and P.N. Pusey, Phys. Rev. E. 52, 5070 (1995). abstract

3. "Viscosity and Structural Relaxation in Concentrated Hard-Sphere Colloids"
            P.N. Segrè, S.P. Meeker, P.N. Pusey and W.C.K. Poon, Phys. Rev. Lett. 75, 958 (1995). Full paper

            2. (a)    "Viscosity and Structural Relaxation in Concentrated Hard-Sphere Colloids-Reply"
                           P.N. Segrè, S.P. Meeker, P.N. Pusey and W.C.K. Poon, Phys. Rev. Lett. 77, 585 (1996). Comment+Reply
            2. (b)    "Viscosity and Structural Relaxation in Concentrated Hard-Sphere Colloids"
                            W.C.K. Poon, S.P. Meeker, P.N. Pusey and P.N. Segrè, J. Non-Newt. Fluids 67, 179 (1996).  abstract

4.    "Scaling of the Dynamic Scattering Function in Concentrated Colloidal Suspensions"
                    P.N. Segrè and P.N. Pusey, Phys. Rev. Lett. 77, 771 (1996).  Full Paper

            1. (a)    "Dynamics of Concentrated Colloidal Suspensions"
                            P.N. Pusey et al., Physica A 235, 1 (1997).  abstract
            1. (b)    "Dynamics and Scaling in Hard-Sphere Colloidal Suspensions"
                            P.N. Segrè and P.N. Pusey, Physica A 235, 9 (1997). abstract

 Other Colloid Links 

  Scientific Working Group Colloidal Physics at Johannes-Gutenberg-Univ., Mainz, Germany.
  Van't Hoff Laboratory at University of Utrecht, Holland.
  Colloid Physics Group at RMIT in Melbourne, Australia.
  Complex Liquids Research at Oklahoma State University.
  Complex Fluids Research at Case Western Reserve University.
  Complex Fluids Research at FOM Institute, Amsterdam, Holland.
  Complex Fluids and Statistical Mechanics at Chemistry Dept., Univ. of Cambridge.
  Polymers and Colloids Group  at Physics Dept., Univ. of Cambridge.
  Complex Liquids  at Univ. of Bristol,. U.K.
  Max-Planck Institute of Colloids and Interfaces  at Teltow, Germany.
   Materials Center  at Univ. of Chicago.
  Colloids, Polymers and Surfaces Center  at Carnegie-Mellon Univ., Pittsburgh.
  Materials and Colloids Group  at Univ. of Santiago de Compostela, Spain.
  Complex Liquids  at Univ. of Konstanz, Germany.
 

Recent Interesting Papers  (click to download PDF files)
 

• On nucleation and crystallization of hard-sphere colloids by the group of Bill van Megen at RMIT.

                         Paper 1,   Paper 2 , Paper 3
 
 

• On LJ simulations of dense hard spheres, cooperative phenomena near to the
glass transition (Mainz, NIST...)

                            Paper 1,  Paper 2,  Paper 3,   Paper 4
 

• John Crocker on measurements of hydrodynamic interactions between 2 spheres.

                         Paper