"The reason we use gold and silver in nanoscience is that they don't oxidize. But finally, with aluminum, nature has given us something we can exploit," Nordlander said.
The second paper by Nordlander and his group predicts quantum effects in plasmonic aluminum that are stronger than those in an analogous gold structure when in the form of a nanomatryushka, multilayer nanoparticles named for the famous Russian nesting dolls. Nordlander discovered the quantum mechanical effects in these materials are strongly connected to the size of the gap between the shell and the core. The paper appeared recently in the ACS journal Nano Letters.
"In addition to being a cheap and tunable material, it exhibits quantum mechanical effects at larger, more accessible and more precise ranges than gold or silver," Nordlander said. "We see this as a foundational paper."
Nordlander used computer simulations to investigate the discrepancies between classical electromagnetics and quantum mechanics, and precisely where the two theories diverge in both gold and aluminum nanomatryushkas. "Aluminum exhibits much more quantum behavior at a given gap size than gold," he said. "Basically for very small gaps, everything is in the quantum realm (where subatomic forces rule), but as you make the gap larger, the system turns to classical physics."
By small, Nordlander means well below a single nanometer (a billionth of a meter). With the gap between core and shell in a gold nanomatryushka at about half a nanometer, he and lead author Vikram Kulkarni, a Rice graduate student, found electrons gained the capability
|Contact: David Ruth|