Theoretical Studies On Surface Plasmon Properties Of Triangular Nanoprisms

Surface plasmon(SP)is the collective oscillation phenomenon of electrons in metal or dielectric materials under the action of external light field.It has wide applications in fields such as biology,chemistry,energy and information.In this paper,we focus on the surface plasmon properties of triangular nanoprisms,and carry out theoretical research from three different perspectives: the far-field scattering spectrum of electromagnetically coupled silicon triangular nanoprism polymers,the near-field enhancement effect of silver triangular nanoprisms and the electromagnetic mode of nanocylinders.In this paper,the surface plasmon scattering properties of silicon nanoprism monomer and dimer,tetramer and hexamer are simulated.It is found that for dimer with decreasing particle gaps,the position of the electric dipole resonance peak is basically unchanged,and the magnetic dipole resonance peak blue shifts;for tetramer and hexamer,due to the introduction of additional transverse electromagnetic coupling interaction,the electric dipole resonance peak shifts obviously,and the magnetic dipole resonance peak splits.In cooperation with PEEM experiment,the influence of the oblique light incidence on the surface plasmon hotspot of triangular silver nanoplate is studied by electromagnetic field simulation.It was quantitatively proved that the symmetry breaking caused by oblique incidence has an important influence on the intensity of the surface plasmon hotspots,and the relevant theoretical results are in good agreement with the experimental observations.The extinction spectra of silver nanoprisms,cylinders and cuboids with different heights were studied by using the electromagnetic multipole method and the quasinormal mode method.It was found that the long wavelength side resonance peak mainly came from the contribution of the electric dipole mode;with the increase of the height of nanoparticles,the contribution of the electric quadrupole mode to the short wavelength side resonance peak increased gradually;when the height-width ratio of nanoparticles reached to about 1:2,the mode of spectral peaks can be assigned reasonably using the electromagnetic multipole method,otherwise the quasinormal mode method should be adopted.The work and achievements in this paper have theoretical significance for a deeper understanding of the surface plasmon properties of triangular nanoprisms.