Small-molecule detection in thiol-yne nanocomposites via surface-enhanced Raman spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) is generally performed on planar surfaces, which can be difficult to prepare and may limit the interaction of the sensing surface with targets in large volume samples. We propose that nanocomposite materials can be configured that both include SERS probes and provide a high surface area-to-volume format, i.e., fibers. Thiol-yne nanocomposite films and fibers were fabricated using exposure to long-wave ultraviolet light after the inclusion of gold nanoparticles (AuNPs) functionalized with thiophenol. A SERS response was observed that was proportional to the aggregation of the AuNPs within the polymers and the amount of thiophenol present. Overall, this proof-of-concept fabrication of SERS active polymers indicated that thiol-yne nanocomposites may be useful as durable film or fiber SERS probes. Properties of the nanocomposites were evaluated using various techniques including UV-vis spectroscopy, µ-Raman spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, and transmission electron microscopy.

2,3-Dichloro-5,8-dimeth-oxy-1,4-naphtho-quinone.

In the crystal structure of the title compound, C(12)H(8)Cl(2)O(4), mol-ecules crystallize in planes parallel to (-204) with an inter-planar distance of 3.288 (2) Š[centroid-centroid distance = 3.819 (2) and slippage = 1.932 (2) Å]. The structure features C-H⋯O inter-actions involving meth-oxy and aromatic H atoms and the carbonyl O atoms as well as a C-H⋯Cl inter-action involving an aromatic H atom. In addition there are short inter-halogen contacts between adjoining mol-ecules [Cl⋯Cl = 3.3709 (5) Å].

Plasmonic nanopillar arrays for large-area, high-enhancement surface-enhanced Raman scattering sensors.

Efforts to create reproducible surface-enhanced Raman scattering (SERS)-based chemical and biological sensors has been hindered by difficulties in fabricating large-area SERS-active substrates with a uniform, reproducible SERS response that still provides sufficient enhancement for easy detection. Here we report on periodic arrays of Au-capped, vertically aligned silicon nanopillars that are embedded in a Au plane upon a Si substrate. We illustrate that these arrays are ideal for use as SERS sensor templates, in that they provide large, uniform and reproducible average enhancement factors up to ∼1.2 × 10(8) over the structure surface area. We discuss the impact of the overall geometry of the structures upon the SERS response at 532, 633, and 785 nm incident laser wavelengths. Calculations of the electromagnetic field distributions and intensities within such structures were performed and both the wavelength dependence of the predicted SERS response and the field distribution within the nanopillar structure are discussed and support the experimental results we report.

Large-area plasmonic hot-spot arrays: sub-2 nm interparticle separations with plasma-enhanced atomic layer deposition of Ag on periodic arrays of Si nanopillars.

Initial reports of plasmonic 'hot-spots' enabled the detection of single molecules via surface-enhanced Raman scattering (SERS) from random distributions of plasmonic nanoparticles. Investigations of systems with near-field plasmonically coupled nanoparticles began, however, the ability to fabricate reproducible arrays of such particles has been lacking. We report on the fabrication of large-area, periodic arrays of plasmonic 'hot-spots' using Ag atomic layer deposition to overcoat Si nanopillar templates leading to reproducible interpillar gaps down to <2 nm. These plasmonic 'hot-spots' arrays exhibited over an order of magnitude increase in the SERS response in comparison to similar arrays with larger interpillar separations.