Static and Dynamic Near-Field Measurements of High-Order Plasmon Modes Induced in a Gold Triangular Nanoplate

Abstract

Precise understanding of the spatiotemporal characteristics of plasmons is essential for the development of applications of plasmonic nanoparticles. In this study, we investigated the spatiotemporal properties of high-order plasmon modes induced in a gold triangular nanoplate by static and dynamic near-field measurements. The near-field transmission measurements revealed that in-plane and out-of-plane polarized plasmon modes were simultaneously excited and these modes spectroscopically and spatially overlapped. The superposition of these modes was visualized in the near-field two-photon excitation image of the nanoplate. We performed time-resolved autocorrelation measurements on the nanoplate and found that the correlation width was broader than the excitation pulse due to the plasmon dephasing process. From the correlation width map of the nanoplate, we experimentally demonstrated that the out-of-plane plasmon mode exhibits a longer dephasing time than the in-plane plasmon mode. These findings indicate that the out-of-plane mode is desirable for improving the performance of plasmons in various applications.

Preparation of Gold Nanoplates Using Ortho Carbonyl Compounds as Capping Agents for Electrochemical Sensing of Lead Ions

“…Thanks to the localized surface plasmon resonance (LSPR) property [1][2][3][4], gold nanoparticles (GNPs) have found many optical and electrochemical applications, including sensing, Raman spectroscopy, biological imaging, catalysis, biomedicine, and so forth [5][6][7][8][9][10]. The plasma properties of GNPs depend on their shape, size, composition and dielectric environment; especially, the near-field enhancement of anisotropic GNPs is often highly amplified due to their sharp structural characteristics [11,12]. In various morphologies, two-dimensional gold nanoplates have attracted much attention due to their unique optical properties, high conductivity, thermal stability and catalytic activity [13][14][15].…”

Characterization of Overlapped Plasmon Modes in a Gold Hexagonal Plate Revealed by Three-Dimensional Near-Field Optical Microscopy

“…In addition, because the volume damping effect should be large in a plate, 33 the spectral overlaps between the nearby plasmon modes become very significant. 34 Because of the spatial and spectral overlaps of numerous plasmon resonances, identification of a single plasmon mode among the overlapped modes is extremely difficult, even when using STEM-EELS imaging methods. In this study, we examined the three-dimensional near-field characteristics of plasmon modes in a gold hexagonal nanoplate by combining conventional near-field optical microscopy with a precise distance regulation between the tip of the near-field probe and sample surface.…”

Plasmon-Enhanced Fluorescence Near Single Gold Nanoplates Studied by Scanning Near-Field Two-Photon Excitation Microscopy

“…Very recently, super-resolution microscopy based on the localization technique has been utilized to visualize the optical field distribution near metallic particles. ,, The technique achieves a high spatial resolution of several tens of nanometers under ambient conditions, but the temporal resolution is limited due to its operation principle. Near-field optical microscopy is capable of achieving both high spatial and temporal resolutions, , and nonlinear and ultrafast imaging of various nanostructures has been reported . In this study, we examine the spatio-temporal characteristics of PEFs near gold triangular nanoplates.…”