Some interesting properties of metals confined in time and nanometer spaceof different shapes

The properties of a material depend on the type of motion its electrons can execute, which depends on the space available for them (i.e., on the degre e of their spatial confinement). Thus, the properties of each material are characterized by a specific length scale, usually on the nanometer dimensio n. If the physical size of the material is reduced below this length scale, its properties change and become sensitive to its size and shape. In this Account we describe some of the observed new chemical, optical, and thermal properties of metallic nanocrystals when their size is confined to the nan ometer length scale and their dynamical processes are observed on the femto - to picosecond time scale.