Browsing by Subject "SERS substrate"
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Item Open Access Anemone-like nanostructures for non-lithographic reproducible large-area and ultra-sensitive SERS substrates(Royal Society of Chemistry, 2014) Daglar, B.; Demirel, G. B.; Khudiyev, T.; Dogan, T.; Tobail O.; Altuntas, S.; Buyukserin F.; Bayındır, MehmetThe melt-infiltration technique enables the fabrication of complex nanostructures for a wide range of applications in optics, electronics, biomaterials, and catalysis. Here, anemone-like nanostructures are produced for the first time under the surface/interface principles of melt-infiltration as a non-lithographic method. Functionalized anodized aluminum oxide (AAO) membranes are used as templates to provide large-area production of nanostructures, and polycarbonate (PC) films are used as active phase materials. In order to understand formation dynamics of anemone-like structures finite element method (FEM) simulations are performed and it is found that wetting behaviour of the polymer is responsible for the formation of cavities at the caps of the structures. These nanostructures are examined in the surface-enhanced-Raman-spectroscopy (SERS) experiment and they exhibit great potential in this field. Reproducible SERS signals are detected with relative standard deviations (RSDs) of 7.2-12.6% for about 10 000 individual spots. SERS measurements are demonstrated at low concentrations of Rhodamine 6G (R6G), even at the picomolar level, with an enhancement factor of ∼1011. This high enhancement factor is ascribed to the significant electric field enhancement at the cavities of nanostructures and nanogaps between them, which is supported by finite difference time-domain (FDTD) simulations. These novel nanostructured films can be further optimized to be used in chemical and plasmonic sensors and as a single molecule SERS detection platform.Item Open Access Concentric ring structures as efficient SERS substrates(Institute of Electrical and Electronics Engineers, 2013) Cinel, N. A.; Cakmakyapan, S.; Ertas, G.; Özbay, EkmelPlasmonic nanopatterned structures that can work as highly efficient surface-enhanced Raman scattering (SERS) substrates are presented in this study. A 'coupled' concentric ring structure has been designed, fabricated, tuned, and compared to an 'etched' concentric ring structure and plain gold film via SERS experiments. The proposed design gives Raman signal intensity 630 times larger than plain gold film and 8 times larger than an 'etched' concentric ring structure. The surface plasmons were imaged with the fluorescence imaging technique and supporting numerical simulations were done.Item Open Access Validation of electromagnetic field enhancement in near-infrared through Sierpinski fractal nanoantennas(Optical Society of American (OSA), 2014) Cakmakyapan, S.; Cinel, N.A.; Cakmak, A.O.; Özbay, EkmelWe introduced fractal geometry to the conventional bowtie antennas. We experimentally and numerically showed that the resonance of the bowtie antennas goes to longer wavelengths, after each fractalization step, which is considered a tool to miniaturize the main bowtie structure. We also showed that the fractal geometry provides multiple hot spots on the surface, and it can be used as an efficient SERS substrate. © 2014 Optical Society of America.