Surface plasmon coupling between different shapes of silver nanostructures and wide-field SPR microscopy

This study investigates the surface plasmon coupling behavior between localized surface plasmons (LSPs) of various silver nanostructure (AgNS) shapes and the propagating surface plasmons (PSPs) of the silver surface. AgNSs of differing shapes (spheres, triangle plates, and hexagonal plates) are synthesized via a one-step solvothermal reduction method, yielding average particle sizes of 70, 160, and 200 nm, respectively. UV–Vis spectroscopy and finite element method simulations are utilized to characterize the LSPs of the AgNSs. While spherical AgNSs display a single Gaussian absorption band at 410 nm, triangle and hexagonal AgNSs exhibit multiple Gaussian absorption bands. Surface plasmon coupling behavior between the LSPs of various AgNS shapes and the PSPs of the Ag surface is investigated using wide-field surface plasmon resonance microscopy (WF-SPRM) and a derived method based on scattering theory. The intensity distribution of the binding event between the AgNSs and the Ag surface is determined by fitting a curve to describe the surface plasmon coupling between AgNSs and the Ag layer.