Create a ball of metal only a few nanometres across and it interacts with light in an entirely different way to larger samples. The light sends waves of electrons called plasmons sloshing across the metal surface. But because of the nanoparticles' size, only certain-sized waves are allowed.Consequently, nanoparticles can be tuned to absorb or emit fairly specific frequencies of light, depending on their size. This makes them useful for tagging biomolecules or for other sensing applications.Now Naomi Halas at the Laboratory for Nanophotonics at Rice University in Houston Texas says one problem is that some nanoparticles, such as nanorods and nanospheres end up responding to a range of frequencies of light because plasmons of various sizes can move around on their surfaces.So she and her team have created rice-shaped nanoparticles which can be tuned much more precisely to specific frequencies. So scientists should be able to track these nanorice particles more easily.
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