Electric field enhancement and concomitant Raman spectral effects at the edges of a nanometre-thin gold mesotriangle

Abstract

The local electric field enhancement at various regions of an individual nanometre-thin gold mesotriangle has been demonstrated both numerically and experimentally. This work provides, for the first time, direct experimental evidence of localized enhancement of Raman signals at three edges of nanometre-thin gold mesotriangles at single particle level, using Raman microscopy. Raman images were collected from mesotriangles of $11 mm edge length and $30 nm thickness, using adsorbed crystal violet as the probe molecule. Spatial distribution and the extent of electric field enhancement around a single mesotriangle are investigated theoretically by finite-difference time-domain (FDTD) simulations. Confocal Raman studies provided direct proof for the substantial electrical field enhancement at the edges and corners compared to the face of the mesotriangle. The simulated electric field enhancement was in the order, corner > edge > surface, which is in complete agreement with the experimental results.

Visualization of Near-Field Enhancements of Gold Triangles by Nonlinear Photopolymerization

“…It has been argued that this is due to the influence of the array, which has not been taken into account in the simulations. Recent investigations on single mesoscopic triangles of micrometer side-length by Sajanlal et al [4] have shown good agreement between the simulations and experiments.…”

“…A tight focus and huge field enhancements by a factor of 10 4 and more can be achieved and are used to guide light in the area of interest [6]. Prominent examples include surface-enhanced Raman spectroscopy [2][3][4], scanning near-field optical microscopy [9] and optics on the nanoscale [8]. In all these cases, the optical response of nanoparticles, governed by a collective excitation of conduction electrons and thus the induction of a polarization of the surface charge is used.…”

“…In parallel with the advances in the generation of nanostructures with their interesting electronic [1], chemical [2][3][4], and optical properties [5][6][7][8], the possibility arose to investigate and use the matter-light interaction on the nanoscale. A very promising route to overcome the diffraction limit and to focus light on the nanometer scale is plasmonics on metallic nano-objects.…”

Wavelength-Selective Photocatalysis Using Gold–Platinum Nanorattles

“…The SERS measurement correlated will with the plasmon field calculation carried out for the high energy plasmon mode that showed that the plasmon field intensity on the surface of AuNS increased as the size of the AuPtNRT increased. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Supporting Information Figure S1 TEM image of gold nanorattles. Figure S2A the SERS spectrum of 4NTP adsorbed on the surface of 15.2±1.9 nm gold nanosphere after irradiation with 532 nm laser for 2 minutes.…”

The synthesis of controlled shape nanoplasmonic silver-silica structures by combining sol-gel technique and direct silver reduction

“…One of the most important parameters determining the sensitivity of SERS substrates is the shape of nanoparticles. For example, sharp-edged silver nanotriangles or nanocubes produce high electromagnetic field at the edges of the nanoparticles and result in a strongly enhanced Raman signal [11,12].…”