In situ surface-enhanced Raman spectroscopy of monodisperse silver nanowire arrays

Abstract

Highly ordered two-dimensional arrays of monodisperse coinage metal nanowires embedded in an alumina matrix have been prepared. When light is propagating in the direction of the long axis of the nanowire, plasmon-enhanced absorption and light guidance of the nanowire were observed by optical microspectroscopy and scanning near-field optical spectroscopy and compared to Mie scattering theory. By selectively dissolving the matrix at a constant etching rate, we detected in situ and ex situ the surface-enhanced Raman scattering (SERS) of organic dyes. In contrast to earlier publications, we find that the SERS signal is linearly proportional to the free-surface area of the nanowires that are in contact with the dye. We cannot detect any change in the enhancement factor due to the releasing of the nanowires from the host structure.

Templated self‐assembly of block copolymers – Toward the rational design of plasmonic nanorods

“…This can be explained by the fact that the gold helices are not physically connected with each other and that the spacing between them is larger than their evanescent field if the light is incident in the direction of their long axes. Similar results were observed by other groups measuring the transmission through silver or gold nanowire arrays in AAO matrices [38]. The refractive index of gold was derived from the analytical model of Etchegoin et al [39] and matches experimental data reported by Johnson and Christy [40].…”

Fabrication and Applications of Metal Nanowire Arrays Electrodeposited in Ordered Porous Templates

“…As a thumb of rule, the distribution in the length of electrodeposited nanowires in porous template channels increases with the wire length. Therefore, in order to have uniform length MNWs for SERS studies either the deposition time must be shortened, yielding nanodots rather than nanowires [Kartopu et al, 2006;Wang et al, 2006], or the initially long MNWs must be levelled by an appropriate post treatment, such as mechanical polishing [Kartopu et al, 2008b] and ion milling [Sauer et al, 2005]. In the latter case, a chemical etching may be applied to increase the exposed area of nanowires ( Fig.…”

“…An in situ chemical etching (in dilute H 3 PO 4 ) is used to probe the temporal change in the SERS spectrum of analyte molecules adsorbed on MNWs/Ag nanowires (Fig. 15c) [Sauer et al, 2005]. The signal intensity first increases to a maximum and then decreases rapidly before it completely vanishes.…”

The Growth Mechanism of Vertically Aligned ZnO Nanowire Arrays on Non‐epitaxial Si(100) Substrates

“…8 Other deposition techniques support the growth of nanostructures using grated substrates or embedded matrices. 9 Still other techniques confine material to 1-D tubular structures [10][11] or arrange granular material in a linear fashion. [12][13] The VLS process, one of the methods frequently applied to grow 1-D ZnO nanostructures, was first described in 1965 for the Au-assisted growth of Si whiskers, 14 and is currently a well-understood system.…”