The exact electromagnetic enhancement mechanism behind SERS,TERS,HERS and SHINERS is one of the issues focused on in the study of enhanced Raman spectroscopy.The three dimensional finite difference time domain method(3D-FDTD),which is widely used in nanoplasmonic simulations,not only provides us with a powerful numerical tool for theoretical studies of the ERS electromagnetic enhancement mechanism,but also serves as a useful tool for the design of ERS-active systems with higher sensitivities and spectral spatial resolution.In this paper,we first introduce the fundamental principles of FDTD algorithms,and then the size-dependent dielectric function of dispersive metallic material is discussed.A comparative study of FDTD and rigorous Mie evaluations of electromagnetic fields in the vicinity of a system of self-similar nanospheres shows an excellent correlation between the two computational methods,directly confirming the validity and accuracy of 3D-FDTD simulations in ERS calculations.Finally,we demonstrate,using a TERS calculation as an example,that the non-uniform mesh method can be more computationally efficient without loss of accuracy if it is applied correctly.
YANG ZhiLinLI QianHongRUAN FangXiongLI ZhiPengREN BinXU HongXingTIAN ZhongQun
