Individual Ag Nanowire Dimer for Surface-Enhanced Raman Scattering

Abstract

We have investigated the polarization-dependent surface-enhanced Raman scattering (SERS) of an individual Ag nanowire (AgNW) dimer, which contains two parallel closely packed AgNWs with very different lengths. Similar cos 2 θ dependence of signal intensities with respect to the polarization angle θ of the incident laser was observed from the dimeric part and the parts of the body as well as the tip of the longer AgNW. The dimeric part was demonstrated to exhibit the strongest SERS effect. The results agree well with our numerical simulations of the electric field distributions using finite element method. The SERS enhancement mechanisms at different parts of the dimer were also discussed which are different in origin.

Efficient Passivation of Ag Nanowires with 11‐Mercaptoundecanoic Acid Probed Using In Situ Total‐Internal‐Reflection Surface‐Enhanced Raman Scattering Spectroscopy

“…Therefore, regions including several neighbor AgNWs were excited to take advantage of the presence of hot spots at contact points between AgNWs that are vertically stacked. [28][29][30] The DFRSM spectrum is then significantly red-shifted ( Figure S6 in SI). Such a shift is commonly reported upon decreasing the interparticle gap between nanostructures, and increasing the amount of hot spots.…”

Controllable synthesis of AgNWs@PDA@AgNPs core–shell nanocobs based on a mussel-inspired polydopamine for highly sensitive SERS detection

“…AgNWs have a large surface area as a one-dimensional nanostructure and high crystallinity enabling them to be an ideal SERS substrate for large-scale sensing application. 15,16 But there existed a problem that momentum is seriously mismatched between the propagating plasmon and photon on the smooth longitudinal surface. 15,16 As a result, the optical coupling into the plasmon modes is very weak at visible-light frequency and the SERS "hot spots" are strictly conned to the sharp AgNWs tips.…”

“…15,16 But there existed a problem that momentum is seriously mismatched between the propagating plasmon and photon on the smooth longitudinal surface. 15,16 As a result, the optical coupling into the plasmon modes is very weak at visible-light frequency and the SERS "hot spots" are strictly conned to the sharp AgNWs tips. 17,18 To resolve this challenge, a variety of approaches have been proposed to increase nanogaps and sharp edges as active SERS "hot spots" on AgNWs longitudinal length and achieve highly sensitive SERS detection.…”

Assembly and application of metal and metal oxide nanowires

“…This result is in agreement previously reported literature which also concluded that SERS intensity of dimer was greater than that of single nanowire. 30 To the best of our knowledge, current literature on SERS studies of AgNW assembled using LB technique have only been performed on 2D assembled AgNW which consisted only parallel gaps. From the results obtained, in addition to parallel gap, vertical gap can also create strong SERS enhancement.…”

“…For single nanowire, the number of hot spots can be increased by either the use of chemical etching to roughen the surface of the AgNW 27 or by assembly of nanoparticles onto silver nanowire to create more inter-particle gaps. 28 Two different groups, Kang et al 29 and Du et al 30 reported the use of manipulator to create nanowires pair. They reported that the hot spots were the dimeric part which had the strongest SERS effect.…”