A Multipurpose Instrument To Measure the Vitreous Properties of Charged Colloidal Solids

We present a new high-precision light-scattering setup to study the properties of colloidal solids. It combines static light scattering, dynamic light scattering, and torsional resonance spectroscopy with a flexible and reliable preparational procedure. All three experiments can be performed quasi-simultaneously on the same mechanically undisturbed sample. Thus, unequivocal identification of glassy behavior in a comprehensive characterization dependent on interaction parameters becomes possible. A detailed description of the mechanics is given. We thoroughly tested the new apparatus on dilute colloidal samples and against commercial reference instruments. We performed a first systematic series of experiments on near index matched charged particles, varying the packing volume fraction between 0.006 and 0.11. The results indicate a new route into the glassy state different from that observed in hard-sphere systems. The range of applications, accuracy, limitations, and possible extensions of the technique are discussed. Copyright 2001 Academic Press.