| Issue |
Europhys. Lett.
Volume 76, Number 5, December 2006
|
|
|---|---|---|
| Page(s) | 972 - 978 | |
| Section | Interdisciplinary physics and related areas of science and technology | |
| DOI | https://doi.org/10.1209/epl/i2006-10357-4 | |
| Published online | 01 November 2006 | |
Length scale dependence of dynamical heterogeneity in a colloidal fractal gel
Laboratoire des Colloïdes, verres et Nanomatériaux (UMR CNRS-UM2 5587) cc26, Université Montpellier 2 - 34095 Montpellier Cedex 5, France
Received:
11
September
2006
Accepted:
9
October
2006
We use time-resolved dynamic light scattering to investigate the
slow dynamics of a colloidal gel. The final decay of the average
intensity autocorrelation function is well described by
![$g_2(q,\tau)-1 \sim \exp[-(\tau/\tau_\mathrm{f})^p]$](/articles/epl/abs/2006/23/epl9684/epl9684_tex_eq1.png)
, with
and p decreasing from 1.5 to 1
with increasing q. We show that the dynamics is not due to a
continuous ballistic process, as proposed in previous works, but
rather to rare, intermittent rearrangements. We quantify the
dynamical fluctuations resulting from intermittency by means of
the variance 
of the instantaneous autocorrelation
function, the analogous of the dynamical susceptibility 
studied in glass formers. The amplitude of χ is found to grow
linearly with q. We propose a simple —yet general— model of
intermittent dynamics that accounts for the q-dependence of both
the average correlation functions and χ.
PACS: 82.70.Dd – Colloids / 64.70.Pf – Glass transitions / 82.70.Gg – Gels and sols
© EDP Sciences, 2006
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