"Colloidal glass transition observed in confinement"
Carolyn R. Nugent, Kazem V. Edmond, Hetal N. Patel, and Eric R. Weeks, Phys. Rev. Lett 99, 025702 (2007).

We study a colloidal suspension confined between two quasi-parallel walls as a model system for glass transitions in confined geometries. The suspension is a mixture of two particle sizes to prevent wall-induced crystallization. We use confocal microscopy to directly observe the motion of colloidal particles. This motion is slower in confinement, thus producing glassy behavior in a sample which is a liquid in an unconfined geometry. For higher volume fraction samples (closer to the glass transition), the onset of confinement effects occurs at larger length scales.