Metal nanoparticles with sharp corners: Universal properties of plasmon   resonances
  We predict the simultaneous occurrence of two fundamental phenomena for metal nanoparticles possessing sharp corners: First, the main plasmonic dipolar mode experiences strong red shift with decreasing corner curvature radius; its resonant frequency is controlled by the apex angle of the corner and the normalized (to the particle size) corner curvature. Second, the split-off plasmonic mode experiences strong localization at the corners. Altogether, this paves the way for tailoring of metal nano-structures providing wavelength-selective excitation of localized plasmons and a strong near-field enhancement of linear and nonlinear optical phenomena. 
B. Sturman, E. Podivilov, and M. Gorkunov
physics.optics cond-mat.mes-hall cond-mat.mtrl-sci