Influence of Surface Quantum Effects on the Near Fields of a Core-Shell Particle Deposited on a Substrate

Accounting for quantum effects in nanoplasmonics is essential for accurate modeling and design of nanophotonic devices. Based on the discrete source method (DSM) we study a polarized light scattering by plasmonic core-shell (metal core $$@$$ dielectric shell) particle deposited on the plane surface of a transparent prism. We investigate the influence of such quantum effect as splitting of the wave function of conduction electrons near the metal surface of core-shell nanoparticle on the distribution of relative field intensity over the shell surface and the integral field enhancement factor. To consider the behavior of electrons near the metal-dielectric interface, mesoscopic boundary conditions are used, including the surface response functions (SRF)—the Feibelman parameters. The excitation of a particle by both propagating and evanescent waves is examined. It was found that using the oblique incidence of the exciting plane wave leads to plasmon resonance enhancement. It turned out that excitation by an evanescent wave enables to increase enhancement factor by more than ten times. It is shown that accounting for the surface quantum effect in plasmonic metal significantly reduces the enhancement factor. In particular, the enhancement factor damping can reach 50 $$\%$$ of its value accompanied by spectral blue shift of 5 nm.