Slow dynamics and ageing of colloidal hard sphere glasses

Echo Dynamic Light Scattering experiments were performed on a colloidal hard sphere glass to measure the intensity autocorrelation function in the range 1 to 104 s. The first derivative of the intensity autocorrelation function is used to determine the inflection point, and isolate the two processes characterizing the decay of the intensity autocorrelation function ¿ the ¿fast¿ process (often designated â decay) and the ¿slow¿ process (á decay). The behaviour of both processes are studied as a function of the age of the colloidal glass, defined as the time since the quench. The end of the fast process follows a stretched exponential law at early ageing times, and becomes more and more stretched, tending eventually towards a power law. The slow process follows a power law for all sample ages.