On the Far Field Optical Properties of Ag-Au Nanosphere Pairs

EZEQUIEL R. ENCINA; EDUARDO A. CORONADO

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Año: 2010 vol. 114 p. 16278 - 16284

1932-7447

In this work we study the far field optical properties of heterodimers composed of a silver and a gold nanosphereof the same size, by means of exact electrodynamics calculations based on the generalized multiparticle Mietheory. We analyze the effect of the incident polarization, nanosphere separation, radius and dielectric mediaon the optical response. The on resonance angular distribution of the scattered radiation is also analyzed. Thenonsymmetrical features of this system allow us to evaluate and perform a careful examination of thecontributions of absorption and scattering from each individual nanosphere to the total extinction of the system.At variance with the homodimer system, the heterodimer exhibits a simultaneous shift of two plasmonicresonances. This feature constitutes a very useful and accurate way to calibrate both interparticle distanceand size at the same time for a given dielectric environment. In this way, we provide a general and completedescription of the far field optical properties of this particular nanostructure, which may be valuable for thedesign and development of plasmonic devices and optical tools and could serve as benchmark calculationsfor future comparisons with experiments.