Length scale dependence of dynamical heterogeneity in a colloidal fractal gel
Length scale dependence of dynamical heterogeneity in a colloidal fractal gel
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DOI：
10.1209/epl/i2006-10357-4
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发表时间：
2006-12-01
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影响因子：
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通讯作者：
Cipelletti, L.
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文献类型：
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作者：
Duri, A.;Cipelletti, L.
我们使用时间分辨动态光散射来研究胶体凝胶的缓慢动力学。平均强度自相关函数的最终衰减由类似于exp[-（tau/tau（f））（p）]的g（2）（q，tau）-1很好地描述，其中tau（f）类似于q（-1），并且p随着q的增加从1.5减小到1。我们表明，动态是由于一个连续的弹道过程中，提出在以前的作品，而是罕见的，间歇性重排。我们通过瞬时自相关函数的方差chi（τ，q）量化了由非线性引起的动态波动，类似于在玻璃制造商中研究的动态磁化率chi（4）。发现chi的振幅随q线性增长。我们提出了一个简单的-但一般的-间歇性动力学模型，占平均相关函数和chi的q依赖。
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 similar to exp[-(tau/tau(f))(p)], with tau(f) similar to q(-1) 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 chi(tau, q) of the instantaneous autocorrelation function, the analogous of the dynamical susceptibility chi(4) studied in glass formers. The amplitude of chi 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 chi.