PNNL

Abstract

We simulate field enhancement distributions encountered in atomic force microscopy (AFM) tip-induced surface enhanced Raman spectroscopy (SERS) experiments (AFM_SERS) by using the frequency-domain three-dimensional finite element method simulation (FEM) to solve Maxwell?s equations of electric field distributions. This paper reports on a numerical simulation of an electromagnetic field enhancement in the vicinity of a metallic atomic force microscopy 9AFM) tip positioned in a close proximity to metallic nanoparticles. We simulated the experimental configurations of involving an AFM metallic tip, one or two silver nanoparticles, and a laser beam of various incident angles under different geometric arrangements. Maximum electric field enhancement is discussed in terms of the relative position of the tip and nanoparticles, as well as the direction of excitation laser propagation. Our results suggest new approaches for using the AFM-SERS tip enhanced near-field imaging samples on surfaces.