Plasmon-Enhanced Raman Scattering of WSe2 Monolayer and Brilliant Cresyl Blue Molecules via One-Dimensional Nanogap with Finite-Difference Time-Domain

Plasmon-enhanced Raman scattering is crucial for investigating a variety of materials, including chemical and biological molecules. A lo-calized surface plasmon resonance (LSPR) must be designed to strengthen the optical field surrounding the plasmonic structure for sensitive Raman sensing because Raman scattering is proportional to the intensity of the optical field. Recent research has focused on various plas-monic structures, such as nanoparticles on mirrors, nanoparticles, tip-enhanced plasmonic structures, and one-dimensional (1D) nanogaps, to improve Raman scattering by designing LSPR. Furthermore, a 1D nanogap provides an effective optical field enhancement because of the extremely confined optical field and strongly excited LSPR. Moreover, a 1D nanogap enables large-area sensing owing to its one-dimensionally extended nature. In this study, we investigated the strongly enhanced optical field distribution and scattering spectra of a 1D Au nanogap using finite-difference time-domain simulations. In addition, we obtained significantly enhanced Raman scattering signals of a WSe2 monolayer and brilliant cresyl blue molecules via a 1D Au nanogap.