Browsing by Subject "Surface enhanced Raman spectroscopy"

Now showing 1 - 6 of 6

Open Access
Concentric ring structures as efficient SERS substrates
(Institute of Electrical and Electronics Engineers, 2013) Cinel, N. A.; Cakmakyapan, S.; Ertas, G.; Özbay, Ekmel
Plasmonic 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.
Open Access
Hyperspectral stochastic optical reconstruction Raman microscopy for label-free super-resolution imaging using surface enhanced Raman spectroscopy
(Springer, 2015) Dana, Aykutlu; Camesano, Terri A.
Super-resolution imaging is an emerging field that has attracted attention in the recent years due to far the reaching impact in biology. All super-resolution techniques use fluorescent labels to image nanoscale biomolecular structures. In contrast, label-free nanoscopic imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with superresolution imaging, overcoming the diffraction limit. In order to achieve this goal, we propose to develop a super-resolved stochastic hyperspectral Raman microscopy technique for imaging of biological architectures. The surface enhanced Raman spectroscopy (SERS) signal contains information about the presence of various Raman bands, allowing for the discrimination of families of biomolecules such as lipids, proteins, DNA. The rich, fluctuating spectral information contained in the single molecule SERS signal possesses a great potential in label-free imaging, using stochastic optical reconstruction microscopy (STORM) methods. In a recently published work, we demonstrated 20 nm spatial resolution using the spectrally integrated Raman signal on highly uniform SERS substrates. A mature version of our method would require development of spectrally resolved nanoscale Raman imaging. Development of stochastic Raman imaging addresses the issue by design and construction of a Raman microscope with hyperspectral imaging capability that will allow imaging of different Raman bands of the SERS signal. Novel computational techniques must also be developed that will enable extraction of hyperspectral STORM images corresponding to different Raman bands, while simultaneously allowing conventional STORM data to be collected using the wellestablished labelling techniques. The resulting technique (Hyperspectral Raman STORM or HyperSTORRM) has the potential to complement the available labeled stochastic imaging methods and enable chemically resolved nanoscopy.
Open Access
Laser photochemical nanostructuring of silicon for surface enhanced raman spectroscopy
(Wiley-VCH Verlag GmbH & Co. KGaA, 2022-07-18) Akbıyık, A.; Avishan, N.; Demirtaş, Ö.; Demir, Ahmet Kemal; Yüce, E.; Bek, A.
In this work, a novel method of fabricating large-area, low-cost surface-enhanced Raman spectroscopy (SERS) substrates is explained which yields nanostructured surface utilizing laser-induced chemical etching of crystalline silicon (Si) in an hydrofluoric acid solution. Nanostructuring of Si surface is followed by deposition of a thin noble metal layer to complete the fabrication procedure. A 50 nm thick silver (Ag) layer is shown to maximize the SERS performance. The SERS effect is attributed to the electromagnetic field enhancement originating from the nanoscale surface roughness of Si that can be controlled by the illumination power, etch duration, and the spot size of the laser beam. The SERS substrates are found to be capable of detecting a Raman analyte dye molecule down to 10−11 m. SERS performance of the Ag deposited substrates are compared to gold (Au) deposited substrates at 660 and 532 nm excitation. Nanostructured Si surface with Ag exhibits stronger SERS than with Au under 532 nm excitation exhibiting an enhancement factor as high as 109. Raman enhancement factor is calculated both by SERS spectra experimentally, and using finite-elements simulation of the electric field enhancement. The applicability of the fabricated substrates is examined by adsorbing different analytes.
Open Access
LIPSS for SERS: Metal coated direct laser written periodic nanostructures for surface enhanced raman spectroscopy
(Wiley-VCH Verlag GmbH & Co. KGaA, 2022-11-18) Erkızan, S. N.; İdikut, F.; Demirtaş, Ö.; Goodarzi, A.; Demir, Ahmet Kemal; Borra, M.; Pavlov, I.; Bek, A.
A novel method of fabricating large-area, low-cost surface-enhanced Raman spectroscopy (SERS) substrates is introduced which yields densely nanostructured surfaces utilizing laser-induced periodic surface structuring (LIPSS) of crystalline silicon (Si). Two different interaction regimes yield low spatial frequency (LSFL) and high spatial frequency (HSFL) LIPSS patterns. Nanostructuring of Si surface is followed by deposition of a thin noble metal layer to complete the fabrication procedure. A 50–70 nm thick Ag layer is shown to maximize the SERS performance. The SERS effect is attributed to the electromagnetic field enhancement originating from the nanoscale surface roughness of Si that can be controlled by LSFL and HSFL nature of the structure. The SERS substrates are found to be capable of detecting a Raman analyte down to 10−11 m. SERS performance of the Ag deposited substrates at 532, 660, and 785 nm excitation wavelengths is compared. Both LSFL and HSFL Si surfaces with 70 nm thick Ag are found to exhibit the strongest SERS under 660 nm excitation exhibiting Raman enhancement factors (EFs) as high as 109. The Raman EFs are calculated both by SERS spectra experimentally, and using finite-elements method simulation of the electric field enhancement where a good agreement is found.
Open Access
Plasmonic absorbers for multispectral and broadband absorption
(SPIE, 2012) Ayaş, Sencer; Güner, Hasan; Türker, Burak; Ekiz, Öner; Dana, Aykutlu
We present polarization dependent multispectral and broadband plasmonic absorbers in the visible spectrum. The spectral characteristics of these structures are tunable over a broad spectrum. Experimental results are verified with the FDTD and RCWA analysis methods. These structures are used as surface enhanced raman spectroscopy(SERS) substrates. Designed structures have resonances that span the Raman Stokes and excitation wavelength. Such structures can be used for energy, LED and other spectroscopy applications. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
Open Access
Raman enhancement on a broadband meta-surface
(American Chemical Society, 2012-07-30) Ayas S.; Güner, H.; Türker, B.; Ekiz, O. O.; Dirisaglik, F.; Okyay, Ali Kemal; Dâna, A.
Plasmonic metamaterials allow confinement of light to deep subwavelength dimensions, while allowing for the tailoring of dispersion and electromagnetic mode density to enhance specific photonic properties. Optical resonances of plasmonic molecules have been extensively investigated; however, benefits of strong coupling of dimers have been overlooked. Here, we construct a plasmonic meta-surface through coupling of diatomic plasmonic molecules which contain a heavy and light meta-atom. Presence and coupling of two distinct types of localized modes in the plasmonic molecule allow formation and engineering of a rich band structure in a seemingly simple and common geometry, resulting in a broadband and quasi-omni-directional meta-surface. Surface-enhanced Raman scattering benefits from the simultaneous presence of plasmonic resonances at the excitation and scattering frequencies, and by proper design of the band structure to satisfy this condition, highly repeatable and spatially uniform Raman enhancement is demonstrated. On the basis of calculations of the field enhancement distribution within a unit cell, spatial uniformity of the enhancement at the nanoscale is discussed. Raman scattering constitutes an example of nonlinear optical processes, where the wavelength conversion during scattering may be viewed as a photonic transition between the bands of the meta-material.