Nanoeggs are described in the July 18 issue of the Proceedings of the National Academy of Sciences.
Like nanoshells, nanoeggs are about 20 times smaller than a red blood cell, and they can be tuned to focus light on small regions of space. But each nanoegg interacts with more light ?about five times the number of wavelengths ?than their nanoshell cousins, and their asymmetric structure also allows them to focus more energy on a particular spot.
"The field of nanophotonics is undergoing explosive growth, as researchers gain greater and greater sophistication in the design and manipulation of light-active nanostructures," said LANP Director Naomi Halas, the Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry. "The addition of nanoeggs and, earlier this year, nanorice to LANP's family of optical nanoparticles is a direct result of our increased understanding of the interaction between light and matter in this critical size regime."
Like nanoshells, nanoeggs have a spherical, non-conducting core that's covered with a thin metal shell. But where the casing on a nanoshell has a uniform thickness ?like the peel covering an orange ?the nanoegg's covering is thicker on one side than the other ?in much the same way that a hard-boiled egg white is thick in some places and thin in others.
The off-center core in the nanoegg radically changes its electrical properties, said co-author and theoretical physicist Peter Nordlander, professor of physics and astronomy. The reasons for this have to do with the odd and often counterintuitiv