geometry effect on plasmon frequency in triangular nanoprism

Surface plasmon resonance is one of the important properties of noble metals which can be controlled by shape, size, and composition. this feature helps scientists to detect individual molecules by surface-enhanced raman spectroscopy (sers) especially in sharp shape because of its significant electromagnetic field. for a specific size of particles, the absorption frequency depends on the particle geometry (sharpness behavior). as a consequence, theoretical investigation on geometry is needed for tuning the surface plasmon frequency and its energy. the effect of geometry on the plasmon frequency for individual triangular prism and truncated triangular prism shapes is considered theoretically. a model is proposed to modify the drude model for describing the plasmon frequency related to the geometry of a truncated nanoprism. two different phenomena are evaluated. in the first step, the effective area which affected on the density is calculated and compared with experimental data. in the second step, the volume of truncated shape and the angle of each edge are investigated separately, and the influence of those on the surface plasmon frequency is calculated and simulated which have good agreement with experimental data.