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SERS spectra in the low-frequency region (130-850 cm −1 ). (a) adenine adso prepared by laser ablation, (b) adenine adsorbed at Fe-Au nanoparticles prepared b of Fe50/Au150/Fe25 film, and (c) SERS spectrum of bare Fe-Au nanoparticles pr ablation of Fe50/Au150/Fe25 film. The excitation wavelength is 632.8 nm.
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Magneto-plasmonic nanoparticles were fabricated using a 1064 nm picosecond-pulsed laser for ablation of Fe/Au and Fe/Au/Fe composite thin films in acetone. Nanoparticles were characterized by electron microscopy, ultraviolet-visible (UV-VIS) absorption, and Raman spectroscopy. Hybrid nanoparticles were arranged on an aluminum substrate by a magneti...
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... Adenine may form several adsorption complexes depending on its tautomerism and ionic form. The characteristic SERS signature of adenine is the highly intense band near 735 cm − 1 , which is attributed to the ring breathing mode [81][82][83]. The Raman spectrum of solid adenine exhibits this band at a considerably lower wavenumber, 723 cm − 1 [83]. ...
... The characteristic SERS signature of adenine is the highly intense band near 735 cm − 1 , which is attributed to the ring breathing mode [81][82][83]. The Raman spectrum of solid adenine exhibits this band at a considerably lower wavenumber, 723 cm − 1 [83]. The mode is sensitive to the interaction of adenine with a surface, and accordingly, the DFT calculations predict interactions with Au and Ag surfaces to occur in N7H tautomeric form (see insert in Fig. 15a) [81,82]. ...
... However, at higher concentrations (10 − 5 M) adenine molecules replace anions from the surface as evidenced by the disappearance of an intense band near 242 cm − 1 and the appearance of a new lower-intensity band at 223 cm − 1 . This band is associated with metal-adsorbate vibrational mode and reflects the direct bonding of adenine with nanoparticle surface [83]. ...
Noble metal nanoparticles, specifically gold and silver, are extensively utilized in sensors, catalysts, surface-enhanced Raman scattering (SERS), and optical-electronic components due to their unique localized surface plasmon resonance (LSPR) properties. The production of these nanoparticles involves various methods, but among the environmentally friendly approaches, laser ablation stands out as it eliminates the need for toxic chemicals during purification. However, nanoparticle aggregation poses a challenge in laser ablation, necessitating the addition of extra materials that contaminate the otherwise clean process. In this study, we investigate the effectiveness of a biocompatible material, potassium chloride (KCl), in preventing particle aggregation. Although salt is known to trigger aggregation, we observed that certain concentrations of KCl can slow down this process. Over an eight-week period, we examined the aggregation rate, extinction behavior, and stability of gold, silver, and hybrid nanoparticles generated in different KCl concentrations. Extinction spectra, SEM images, SERS signal strength, and zeta potential were analyzed. Our results demonstrate that laser ablation in water and salt solutions yields nanoparticles with a spherical shape and a negative zeta potential. Importantly, we identified the optimal concentration of potassium chloride salt that maintains solution stability and SERS signal strength. Adsorbed chloride ions on silver nanoparticles were evidenced by low-frequency SERS band near 242 cm − 1. A better understanding of the effect of KCl concentration on the properties of noble metal nanoparticles can lead to improved generation protocols and the development of tailored nanoparticle systems with enhanced stability and SERS activity.
... The depth of ablation depends on the optical properties of ablated material and various laser process parameters, like laser irradiation wavelength, pulse duration, pulse repetition rate, number of passes, and focusing conditions 24 , which define laser irradiation fluence on the material's surface. Laser processes are widely used for various micromachining applications such as drilling 25 , cutting 26 , or synthesis of nanoparticles 27 . The laser ablation process has been demonstrated to be a versatile tool for antenna formation. ...
This study investigates antenna performance based on its manufacturing process. Two types of planar antennas are manufactured on FR-4 dielectric using three different techniques: traditional lithography, laser ablation, and the novel SSAIL (selective surface activation by laser) technique. Various characteristics, such as reflection coefficient, gain, half-power beamwidth, and surface conductivity, are measured to compare the results. These findings offer invaluable insights for choosing the most suitable antenna manufacturing technique, particularly since the SSAIL technique has not been previously compared to alternative methods in the context of antenna production. In both types of antennas, the highest gain is achieved using laser ablation, with the slot-loaded patch antenna reaching 8.5 dBi and the Yagi-Uda antenna reaching 9.76 dBi. Antennas manufactured using SSAIL technology are notable for their excellent resolution and usefulness in constructing structures on non-metallized dielectrics.
Herein, it is demonstrated that copper (Cu) nanoparticle‐based surfaces prepared via a wet‐chemical method exhibit considerable enhancement of the Raman signal for a monolayer of adenine, guanine, riboflavin, 4‐mercaptobenzoic acid, and potassium thiocyanate analytes upon excitation with a laser in the wavelength range of 229–325 nm. The results reveal a notable enhancement of the Raman signal in the surface‐enhanced Raman scattering (SERS) spectra of the analytes in the deep UV(ultraviolet) spectral ranges, a phenomenon previously unreported for Cu‐based surfaces, which, according to current knowledge, typically exhibit enhancement only in the red and near‐infrared spectral regions. Several analytes of different chemical natures are tested, which allow to test the hypothesis that π‐conjugated molecules localized on the copper surface are more likely to contribute to the chemical enhancement of Raman signal. This enhancement arises from their capacity for charge delocalization, effective orbital alignment with the metal and resonance with electronic transitions in the UV spectral region. Based on these findings, the chemical enhancement mechanism related to charge transfer is the most plausible explanation for the observed enhancement in the UV‐SERS signals of the investigated molecules on Cu surfaces.
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The present study introduces a novel method for the synthesis of magneto-plasmonic nanoparticles (MPNPs) with enhanced functionality for surface-enhanced Raman scattering (SERS) applications. By employing pulsed laser ablation in liquid (PLAL) to synthesize plasmonic nanoparticles and wet chemistry to synthesize magnetic nanoparticles, we successfully fabricated chemically pure hybrid Fe3O4@Au and Fe3O4@Ag nanoparticles. We demonstrated a straightforward approach of an electrostatic attachment of the plasmonic and magnetic parts using positively charged polyethylenimine. The MPNPs displayed high SERS sensitivity and reproducibility, and the magnetic part allowed for the controlled separation of the nanoparticles from the reaction mixture, their subsequent concentration, and their precise deposition onto a specified surface area. Additionally, we fabricated alloy based MPNPs from AgxAu100–x (x = 50 and 80 wt %) targets with distinct localized surface plasmon resonance (LSPR) wavelengths. The compositions, morphologies, and optical properties of the nanoparticles were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis spectroscopy, and multiwavelength Raman spectroscopy. A standard SERS marker, 4-mercaptobenzoic acid (4-MBA), validated the enhancement properties of the MPNPs and found an enhancement factor of 2 × 10⁸ for the Fe3O4@Ag nanoparticles at 633 nm excitation. Lastly, we applied MPNP-enhanced Raman spectroscopy for the analysis of the biologically relevant molecule adenine and found a limit of detection of 10–7 M at 785 nm excitation. The integration of PLAL and wet chemical methods enabled the relatively fast and cost-effective production of MPNPs characterized by high SERS sensitivity and signal reproducibility that are required in various fields, including biomedicine, food safety, materials science, security, and defense.
