The glassy state of argon is examined from the standpoint that this state of a system is an ensemble of frozen excited configurations. The basis is experimental data for deposition of an argon stream on a very cold substrate; the measurements provide the dependence of the saturated vapor pressure over this system. The immobile state prepared by such deposition is an amorphous argon, and the activation energy for its transition to the crystalline state is found from a theoretical model. A criterion is established for the minimum cooling rate of liquid rare gases to form the glassy state. An analogous glassy state for clusters is analyzed, and a minimum rate of cooling for its formation is also developed. The glassy state of a bulk system of atoms bound by pair interactions, thermodynamically unstable, relaxes to equilibrium by diffusion of voids to the boundary; the corresponding phase change of a cluster can be thought of at least as easily in terms of diffusion of atoms to sites in its lowest-energy, ordered configuration. A common feature of these small systems is the way their counterparts of the glassy state form from fast cooling of liquid aggregate states to become frozen liquid states. (C) 2003 American Institute of Physics.