  The optical responses of structured array of noble-metal nanoparticle dimers
immersed in a glass matrix are investigated theoretically, motivated by the
recent experimental observation of the splitting of the surface plasmon bands
in silver arrays. To capture the strong electromagnetic coupling between the
two approaching particles in a silver dimer, the spectral representation of the
multiple image formula has been used, and a semiclassical description of the
silver dielectric function is adopted from the literature. The splitting of
plasmon resonance band of the incident longitudinal and transverse polarized
light is found to be strongly dependent on the particle diameter and their
separation. Our results are shown in accord with the recent experimental
observation. Moreover, a large redshift for the longitudinal polarization can
be reproduced. The reflectivity spectrum is further calculated for a dilute
suspension of dimer arrays.
