scholarly journals On the Large Near-Field Enhancement on Nanocolumnar Gold Substrates

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pablo Díaz-Núñez ◽  
José Miguel García-Martín ◽  
María Ujué González ◽  
Raquel González-Arrabal ◽  
Antonio Rivera ◽  
...  
Keyword(s):  
Hot Spots ◽  
Near Field ◽  
Broad Band ◽  
Field Enhancement ◽  
Surface Enhanced Raman Spectroscopy ◽  
Plasmonic Nanostructures ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Nanostructured Gold ◽  
High Roughness

Abstract One of the most important and distinctive features of plasmonic nanostructures is their ability to confine large electromagnetic fields on nanometric volumes; i.e., the so-called hot spots. The generation, control and characterization of the hot spots are fundamental for several applications, like surface-enhanced spectroscopies. In this work, we characterize the near-field distribution and enhancement of nanostructured gold thin films fabricated by glancing angle deposition magnetron sputtering. These films are composed of columnar nanostructures with high roughness and high density of inter-columnar gaps, where the electromagnetic radiation can be confined, generating hot spots. As expected, the hot spots are localized in the gaps between adjacent nanocolumns and we use scattering-type scanning near-field optical microscopy to image their distribution over the surface of the samples. The experimental results are compared with finite-difference time-domain simulations, finding an excellent agreement between them. The spectral dependence of the field-enhancement is also studied with the simulations, together with surface-enhanced Raman spectroscopy at different excitation wavelengths in the visible-NIR range, proving a broad-band response of the substrates. These findings may result in interesting applications in the field of surface-enhanced optical spectroscopies or sensing.

scholarly journals Surface-Enhanced Raman Spectroscopy of Dye and Thiol Molecules Adsorbed on Triangular Silver Nanostructures: A Study of Near-Field Enhancement, Localization of Hot-Spots, and Passivation of Adsorbed Carbonaceous Species

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Manuel R. Gonçalves ◽  
Fabian Enderle ◽  
Othmar Marti
Keyword(s):  
Raman Spectroscopy ◽  
Hot Spots ◽  
Near Field ◽  
Field Enhancement ◽  
Surface Enhanced Raman Spectroscopy ◽  
Spherical Particles ◽  
Silver Nanostructures ◽  
Dye Molecules ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Surface-enhanced Raman spectroscopy (SERS) of thiols and dye molecules adsorbed on triangular silver nanostructures was investigated. The SERS hot-spots are localized at the edges and corners of the silver triangular particles. AFM and SEM measurements permit to observe many small clusters formed at the edges of triangular particles fabricated by nanosphere lithography. Finite-element calculations show that near-field enhancements can reach values of more than 200 at visible wavelengths, in the gaps between small spherical particles and large triangular particles, although for the later no plasmon resonance was found at the wavelengths investigated. The regions near the particles showing strong near-field enhancement are well correlated with spatial localization of SERS hot-spots done by confocal microscopy. Silver nanostructures fabricated by thermal evaporation present strong and fast fluctuating SERS activity, due to amorphous carbon contamination. Thiols and dye molecules seem to be able to passivate the undesired SERS activity on fresh evaporated silver.

scholarly journals Electromagnetic Field Enhancement of Nanostructured TiN Electrodes Probed with Surface-Enhanced Raman Spectroscopy

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 487
Author(s):  
Ibrahim Halil Öner ◽  
Christin David ◽  
Christine Joy Querebillo ◽  
Inez M. Weidinger ◽  
Khoa Hoang Ly
Keyword(s):  
Electromagnetic Field ◽  
Near Field ◽  
Field Enhancement ◽  
Surface Enhanced Raman Spectroscopy ◽  
Enhancement Effect ◽  
Surface Binding ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Optical Region ◽  
Rigorous Coupled Wave

We present a facile approach for the determination of the electromagnetic field enhancement of nanostructured TiN electrodes. As model system, TiN with partially collapsed nanotube structure obtained from nitridation of TiO2 nanotube arrays was used. Using surface-enhanced Raman scattering (SERS) spectroscopy, the electromagnetic field enhancement factors (EFs) of the substrate across the optical region were determined. The non-surface binding SERS reporter group azidobenzene was chosen, for which contributions from the chemical enhancement effect can be minimized. Derived EFs correlated with the electronic absorption profile and reached 3.9 at 786 nm excitation. Near-field enhancement and far-field absorption simulated with rigorous coupled wave analysis showed good agreement with the experimental observations. The major optical activity of TiN was concluded to originate from collective localized plasmonic modes at ca. 700 nm arising from the specific nanostructure.

scholarly journals Preparation of Fe3O4-Ag Nanocomposites with Silver Petals for SERS Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1288
Author(s):  
Thi Thuy Nguyen ◽  
Fayna Mammeri ◽  
Souad Ammar ◽  
Thi Bich Ngoc Nguyen ◽  
Trong Nghia Nguyen ◽  
...  
Keyword(s):  
Self Assembly ◽  
Hot Spots ◽  
Surface Enhanced Raman Spectroscopy ◽  
Electrical Field ◽  
Stabilizing Agents ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Sers Sensing ◽  
Applied Electrical Field ◽  
Positively Charged

The formation of silver nanopetal-Fe3O4 poly-nanocrystals assemblies and the use of the resulting hetero-nanostructures as active substrates for Surface Enhanced Raman Spectroscopy (SERS) application are here reported. In practice, about 180 nm sized polyol-made Fe3O4 spheres, constituted by 10 nm sized crystals, were functionalized by (3-aminopropyl)triethoxysilane (APTES) to become positively charged, which can then electrostatically interact with negatively charged silver seeds. Silver petals were formed by seed-mediated growth in presence of Ag+ cations and self-assembly, using L-ascorbic acid (L-AA) and polyvinyl pyrrolidone (PVP) as mid-reducing and stabilizing agents, respectively. The resulting plasmonic structure provides a rough surface with plenty of hot spots able to locally enhance significantly any applied electrical field. Additionally, they exhibited a high enough saturation magnetization with Ms = 9.7 emu g−1 to be reversibly collected by an external magnetic field, which shortened the detection time. The plasmonic property makes the engineered Fe3O4-Ag architectures particularly valuable for magnetically assisted ultra-sensitive SERS sensing. This was unambiguously established through the successful detection, in water, of traces, (down to 10−10 M) of Rhodamine 6G (R6G), at room temperature.

scholarly journals Porous carbon nanowire array for surface-enhanced Raman spectroscopy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nan Chen ◽  
Ting-Hui Xiao ◽  
Zhenyi Luo ◽  
Yasutaka Kitahama ◽  
Kotaro Hiramatsu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Porous Carbon ◽  
Hot Spots ◽  
Strong Dependence ◽  
Nanowire Array ◽  
Surface Enhanced Raman Spectroscopy ◽  
Localized Surface Plasmon ◽  
Sers Substrate ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Abstract Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for vibrational spectroscopy as it provides several orders of magnitude higher sensitivity than inherently weak spontaneous Raman scattering by exciting localized surface plasmon resonance (LSPR) on metal substrates. However, SERS can be unreliable for biomedical use since it sacrifices reproducibility, uniformity, biocompatibility, and durability due to its strong dependence on “hot spots”, large photothermal heat generation, and easy oxidization. Here, we demonstrate the design, fabrication, and use of a metal-free (i.e., LSPR-free), topologically tailored nanostructure composed of porous carbon nanowires in an array as a SERS substrate to overcome all these problems. Specifically, it offers not only high signal enhancement (~106) due to its strong broadband charge-transfer resonance, but also extraordinarily high reproducibility due to the absence of hot spots, high durability due to no oxidization, and high compatibility to biomolecules due to its fluorescence quenching capability.

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