This high-resolution transmission electron micrograph taken at the Brookhaven's Center for Functional Nanomaterials reveals the arrangement of cerium oxide nanoparticles (bright angular "slashes" at the bottom of the image) supported on a titania substrate (background), a combination being explored as a catalyst for splitting water molecules to release hydrogen as fuel and for other energy-transformation reactions. Nanoparticles are particles between 1 and 100 nanometers in size. In nanotechnology, a particle is defined as a small object that behaves as a whole unit with respect to its transport and properties. Particles are further classified according to diameter. Nanoparticle research is currently an area of intense scientific interest due to a wide variety of potential applications in biomedical, optical and electronic fields. Nanotechnology (nanotech) is the manipulation of matter on an atomic, molecular, and supramolecular scale.