Preparation of phosphate samples for oxygen isotope analysis

A comparative study of the solubilizing effect of polycyclic aromatic hydrocarbon (PAHs) on single-walled carbon nanotubes (SWCNTs) produced by the high-pressure decomposition of carbon monoxide (HiPco) and the arc discharge (AD) method has been carried out with the aid of fluorescence and Raman spectroscopy. For this study, polyphenyl and polyacene PAHs of different lengths are used. From the study it has been found that the binding energy of PAHs with AD SWCNTs is the same as that with HiPco SWCNTs. Shorter PAHs molecules better solubilize SWCNTs and in general smaller-diameter SWCNTs. Thus, given their smaller-diameter profile, significantly larger numbers of HiPco SWCNTs are solubilized compared to the number of AD SWCNTs.

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A Comparative Study of the Interaction of Different Polycyclic Aromatic Hydrocarbons on Different Types of Single Walled Carbon Nanotubes

Very recently, wing scales of natural Lepidopterans (butterflies and moths) manifested themselves in providing excellent three dimensional (3D) hierarchical structures for surface-enhanced Raman scattering (SERS) detection. But the origin of the observed enormous Raman enhancement of the analytes on 3D metallic replicas of butterfly wing scales has not been clarified yet, hindering a full utilization of this huge natural wealth with more than 175 000 3D morphologies. Herein, the 3D sub-micrometer Cu structures replicated from butterfly wing scales are successfully tuned by modifying the Cu deposition time. An optimized Cu plating process (10 min in Cu deposition) yields replicas with the best conformal morphologies of original wing scales and in turn the best SERS performance. Simulation results show that the so-called “rib-structures” in Cu butterfly wing scales present naturally piled-up hotspots where electromagnetic fields are substantially amplified, giving rise to a much higher hotspot density than in plain 2D Cu structures. Such a mechanism is further verified in several Cu replicas of scales from various butterfly species. This finding paves the way to the optimal scale candidates out of ca. 175 000 Lepidopteran species as bio-templates to replicate for SERS applications, and thus helps bring affordable SERS substrates as consumables with high sensitivity, high reproducibility, and low cost to ordinary laboratories across the world.

High-Density Hotspots Engineered by Naturally Piled-Up Subwavelength Structures in Three-Dimensional Copper Butterfly Wing Scales for Surface-Enhanced Raman Scattering Detection

SERS enhancement dependence on the diameter and aspect ratio of silver-nanowire array fabricated by anodic aluminium oxide template

After thermal deposition of silver films onto n-layer graphenes, the following results have been obtained. First, the dependence of silver morphologies on the layer number is studied via controlling the sample temperature at 298, 333, and 373 K. This can be attributed to the changes in surface properties and/or surface diffusion coefficient of n-layer graphenes at different temperatures. Second, Raman scattering of n-layer graphenes is greatly enhanced after Ag deposition and the enhancement factors depend on the layer number of n-layer graphenes. Monolayer graphene has the largest enhancement factors, and the enhancement factors decrease with layer number increasing. For graphite, almost no enhancement effect has been detected. Third, the dependences of the enhancement factors on laser wavelength, thickness, and morphologies (nanoparticle size and spacing) of silver film are also studied. The Raman enhancement observed here is mainly attributed to the coupled surface plasmon resonance (SPR) absorption of...

Y. Mo

Papers

Surface science lettersSurface enhanced Raman scattering of pyridine on silver surfaces of different roughness

The influence of surface roughness on the Raman scattering of pyridine on copper and silver surfaces

Surface enhanced Raman scattering of pyridine on silver surfaces of different roughness