Nano light

It might be possible to tweak the optical properties of nanoparticles by changing their size as well as their chemical composition, according to a study by the National Renewable Energy Laboratory, Colorado. Alex Zunger and colleagues have used quantum mechanics to show how electron-hole exchange interactions in quantum dots depend on the size of the semiconductor material from which the dots are made and how the exchange interaction depends on the electronic structure of the quantum-dot semiconductor material. The result is important from a fundamental viewpoint because it reveals the origin of electron-hole exchange interactions and helps explain light emission in these materials on the nanoscale.