We investigate the properties of solids that appear at very small sizes. The properties are different because the boundary changes the way the atoms and electrons interact. This is used to design materials with novel optical and electrical properties. One nanometer is one billionth of the meter, which is only 5 to 10 atoms across. In our lab, the nanostructures are chemically synthesized from solution by colloidal synthesis. This picture shows pipettes of fluorescent colloidal solutions of CdSe/ZnS cores/shell nanoparticles ranging from ~3 nm to 7 nm in diameter.