Designing the plasmonic response of shell nanoparticles: Spectral representation

A spectral representation formalism in the quasistatic limit is developed to study the optical response of nanoparticles, such as nanospheres, nanospheroids, and concentric nanoshells. A transfer matrix theory is formulated for systems with an arbitrary number of shells. The spectral representation formalism allows us to analyze the optical response in terms of the interacting surface plasmons excited at the interfaces by separating the contributions of the geometry from those of the dielectric properties of each shell and surroundings. Neither numerical nor analytical methods can do this separation. These insights into the physical origin of the optical response of multishelled nanoparticles are very useful for engineering systems with desired properties for applications in different fields ranging from materials science and electronics to medicine and biochemistry. (C) 2011 American Institute of Physics. [doi:10.1063/1.3541257]