US Patent 7371457 - Core/shell optical nanoparticles

http://www.freepatentsonline.com/7371457.html

This patent from Rice University has fairly early priority (3/12/1997) and is basic to core/shell optical nanoparticles. Although not the first to teach such particles (see U.S. 5,023,139) the nanoparticles of the prior art are noted as not taking into account surface scattering and to have broader spectra whereas the claimed nanoparticles have a thin metallic shell layer providing a smaller electron mean free path for applications such as Surface Enhanced Raman Spectroscopy. Claim 1 reads:

1. A nanoparticle comprising:

at least one non-conducting inner layer;

at least one conducting shell layer surrounding the inner layer, the thickness of said shell layer being independent of the radius of said inner layer and less than the bulk electron mean free path of the material comprising the shell layer.