Synthesis of colloidal silica dumbbells.

We describe the synthesis and characterization of stable suspensions of monodisperse fluorescently labeled silica dumbbell particles. Pure dispersions of silica dumbbells with center-to-center lengths from 174 nm to 2.3 microm were produced with a variety of aspect ratios. Individual particles in concentrated dispersions of these particles could be imaged with confocal microscopy. These particles can be used as a colloidal model system for addressing fundamental questions about crystal and glass formation of low-aspect-ratio anisotropic particles. They also have potential in photonic applications and electro-optical devices.