Localized enhancement of electric field in tip-enhanced Raman spectroscopy using radially and linearly polarized light

Abstract

Finite-Difference Time-Domain (FDTD) calculations are used to characterize the electric field in the vicinity of a sharp silver or gold cone with an apex diameter of 10 nm. The simulations are utilized to predict the intensity and the distribution of the locally enhanced electric field in tip-enhanced Raman spectroscopy (TERS). A side-by-side comparison of the enhanced electric field induced by a radially and a linearly polarized light in both gap-mode and conventional TERS setup is performed. For this purpose, a radially polarized source is introduced and integrated into the FDTD modeling. Additionally, the optical effect of a thin protective layer of alumina on the enhancement of the electric field is investigated.

Relation between plasmonic tip emission and electromagnetic enhancement evidenced in tip‐enhanced Raman spectroscopy

“…Our study offers the opportunity to improve the preparation of TERS tips by a systematic comparison between the intensity of the TERS signal and the tip optical response. Several numerical simulations have already demonstrated the best configuration to achieve high electromagnetic enhancements . The role of polarization, tip‐to‐surface distance, excitation wavelength, and so forth, is clearly evidenced in these studies.…”

Photothermal Microscopy of Coupled Nanostructures and the Impact of Nanoscale Heating in Surface-Enhanced Raman Spectroscopy

“…On the other hand, the calculated electric field in the gap between the particles shows large changes with polarization, see Figure 2, consistent with previous studies. 51, 54 …”

Tip-enhanced Raman scattering—Targeting structure-specific surface characterization for biomedical samples

“…5 exemplifies the field distribution for two configurations: with a 10 nm gold layer and without a metal substrate [82]. Fig.…”

“…The enhancement factor goes from 8 to 10 for linearly polarized along the tip axis, and 82 to 322 for linearly polarized perpendicular to tip axis and from 720 to 11510 for radially polarized light. It has been shown that objects that are sandwiched between the tip and flat gold surfaces would show high local Raman signal enhancement [82,83].…”