Resonant wavelength determination of ovoid metallic nanoparticle pair

An end-to-end ovoid metallic nanoparticle pair is introduced, and its resonant wavelength can be determined by the particle geometry, particle separation, outside medium, and metallic material. The resonant peak shifts as a function of particle separation under different adjacent ends' aspect ratios obey a universal scale after a normalization process. The scaled peak shifts are exponentially fitted, and the two fitting coefficients are obtained separately for the nanoparticle pair made of silver, gold, and aluminum immersed in several media. Equations are found in which the fitting coefficients can be derived from the medium and metallic refractive index. These equations are used to predict the resonant wavelength of the nanoparticle pair made of gallium in various media.