arXiv subjects

Nicolo Maccaferri

Publications and source records attributed to Nicolo Maccaferri.

10 recordsLinked to original sources

arXiv2026

Nanoporous Copper Films as Platform for UV-SERS: Sensitivity and Ability to Perform Chiral Discrimination

Surface enhanced Raman spectroscopy (SERS) in the ultraviolet (UV) region offers important advantages for biomolecular detection, including resonance enhancement and reduced fluorescence interference. However, the development of UV SERS substrates that combine low cost, reproducibility, and chemical stability remains challenging. Here, we employ a dry synthesis approach to fabricate nanoporous Cu and copper oxide (CuO) films on silicon substrates and systematically evaluate their UV SERS performance using adenine as a Raman reporter under 325 nm excitation. Among the substrates investigated, nanoporous Cu exhibits the strongest enhancement, enabling adenine detection down to 10 microM. In contrast, no detectable adenine Raman signal is observed under 532 nm excitation, indicating that the enhancement is dominated by a UV induced chemical, charge transfer mechanism rather than conventional electromagnetic enhancement. The Cu substrates further enable the UV Raman spectroscopy of streptavidin, as a test protein, and, more interestingly, the discrimination between L and D tryptophane based solely on differences in UV SERS intensity, without chiral selectors or additional surface functionalization. By varying the substrate rotation speed during metal evaporation, the enantioselective response can be tuned, yielding L over D intensity ratios from 1.10 to 2.35 and demonstrating the critical role of substrate morphology in chiral discrimination. The dry synthesized nanoporous films provide a simpler, scalable, and ligand free fabrication strategy while offering additional capability for enantioselective detection. These findings establish dry processed nanoporous Cu films as promising platforms for UV-SERS biosensing and label free chiral analysis.

physics.app-ph↗

arXiv2025

Copper-based disordered plasmonic system with dense nanoisland morphology

Dry synthesis is a highly versatile method for the fabrication of nanoporous metal films, since it enables easy and reproducible deposition of single or multi-layer(s) of nanostructured materials that can find intriguing applications in plasmonics, photochemistry and photocatalysis, to name a few. Here, we extend the use of this methodology to the preparation of copper nanoislands that represent an affordable and versatile example of disordered plasmonic substrate. We perform detailed characterizations of the system using several techniques such as spectroscopic ellipsometry, cathodoluminescence, electron energy loss spectroscopy, ultrafast pump-probe spectroscopy and second-harmonic generation with the aim to investigate the optical properties of these systems in an unprecedented systematic way. Our study represents the starting point for future applications of this new disordered plasmonic system ranging from sensing to photochemistry and photocatalysis.

physics.app-ph↗

arXiv2024

Porous aluminium decorated with rhodium nanoparticles, preparation and use as platform for UV plasmonics

There is a high current interest for novel plasmonic platforms and materials able to extend their applicability into the ultraviolet (UV) region of the electromagnetic spectrum. In the UV it is possible to explore spectral properties of biomolecules with small cross section in the visible spectral range. However, most used metals in plasmonics have their resonances at wavelengths > 350 nm. Aluminum and rhodium are two interesting candidate materials for UV plasmonics, and in this work we developed a simple and low-cost preparation of functional substrates based on nanoporous aluminum decorated with rhodium nanoparticles. We demonstrate that these functionalized nanoporous metal films can be exploited as plasmonic materials suitable for enhanced UV Raman spectroscopy

physics.app-ph↗

arXiv2023

Dry synthesis of bi-layer nanoporous metal films as plasmonic metamaterial

Nanoporous metals are a class of nanostructured materials finding extensive applications in multiple fields thanks to their unique properties attributed to their high surface area and interconnected nanoscale ligaments. They can be pre-pared following different strategies, but the deposition of an arbitrary pure porous metal is still challenging. Recently, a dry synthesis of nanoporous films based on the plasma treat-ment of metal thin layers deposited by physical vapour deposition has been demonstrated, as a general route to form pure nanoporous films from a large set of metals. An interest-ing aspect related to this approach is the possibility to apply the same methodology to deposit the porous films as a multilayer. In this way, it is possible to explore the properties of different porous metals in close contact. As demonstrated in this paper, interesting plasmonic properties emerge in a nanoporous Au-Ag bi-layer. The versatility of the method coupled with the possibility to include many different metals, provides an opportunity to tailor their optical resonances and to exploit the chemical and mechanical properties of compo-nents, which is of great interest to applications ranging from sensing, to photochemistry and photocatalysis.

physics.app-ph↗

arXiv2019

Electrophoretic deposition of WS2 flakes on nanoholes arrays. Role of the used suspension medium

Here we optimized the electrophoretic deposition process for the fabrication of WS2 plasmonic nanohole integrated structures. We showed how the conditions used for the site selective deposition influenced the properties of the deposited flakes. In particular, we investigated the effect of different suspension medium used during the deposition both in the efficiency of the process and in the stability of WS2 flakes, which were deposited on a ordered arrays of plasmonic nanostructures.

cond-mat.mtrl-sci↗

arXiv2019

Nanoparticles manipulation in 3D nanotips excited with plasmonic vortex

Recent advances in nanotechnologies have prompted the need for tools to accurately and non invasively manipulate individual nanoobjects. Among the possible strategies, optical forces have been widely used to enable nano optical tweezers capable of trapping or moving a specimen with unprecedented accuracy. Here, we propose an architecture consisting of a nanotip excited with a plasmonic vortex enabling effective dynamical control of nanoparticles in three dimensions. The optical field generated by the structure can be used to manipulate single dielectric nanoparticles acting on the total angular momentum of light used to illuminate the structure. We demonstrate that it is possible to stably trap or force the beaming of the particle from specific points, thus enabling a new platform for nanoparticle manipulation and sorting.

physics.optics↗

arXiv2019

Chemically-controlled self-assembly of hybrid plasmonic nanopores on graphene

Thanks to the spontaneous interaction between noble metals and biological scaffolds, nanomaterials with unique features can be achieved following relatively straightforward and cost-efficient synthetic procedures. Here, plasmonic silver nanorings are synthesized on a ring-like Peroxiredoxin (PRX) protein and used to assemble large arrays of functional nanostructures. The PRX protein drives the seeding growth of metal silver under wet reducing conditions, yielding nanorings with outer and inner diameters down to 28 and 3 nm, respectively. The obtained hybrid nanostructures can be deposited onto a solid-state membrane in order to prepare plasmonic nanopores. In particular, the interaction between graphene and PRX allows for the simple preparation of ordered arrays of plasmonic nanorings on a 2D-material membrane. This fabrication process can be finalized by drilling a nanometer scale pore in the middle of the ring. Fluorescence spectroscopic measurements have been used to demonstrate the plasmonic enhancement induced by the metallic ring. Finally, we support the experimental findings with some numerical simulations showing that the nanorings are endowed with a remarkable plasmonic field within the cavity. Our results represent a proof of concept of a fabrication process that could be suitable for nanopore-based technologies such as next-generation sequencing and single-molecule detection.

physics.app-ph↗

arXiv2019

Hybrid Metal-Dielectric Plasmonic Zero Mode Waveguide for Enhanced Single Molecule Detection

We fabricated hybrid metal-dielectric nanoantennas and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of silicon and gold on a transparent substrate. The optical characterization is done via fluorescence measurements. We characterized the fluorescence enhancement, as well as the lifetime and detection volume reduction for each wavelength. We observe that the hybrid metal-dielectric nanoantennas behave as enhanced Zero Mode Waveguides in the near-infrared spectral region. Their detection volume is such that they can perform enhanced single-molecule detection at tens of microM. However, a wavelength blue-shift of 40 nm dramatically decreases the performance of the nanoantennas. We compared their behavior with that of a golden ZMW, and we verified that the dielectric silicon layer improves the design. We interpreted the experimental observations with the help of numerical simulations. In addition, the simulations showed that the field enhancement of the structure highly depends on the incoming beam: tightly focused beams yield lower field enhancements than plane-waves.

physics.app-ph↗

arXiv2018

Controlled integration of MoS2 flakes on nanopores by means of electrophoretic deposition

We propose an easy and robust strategy for the versatile integration of 2D material flakes on plasmonic nanoholes by means of controlled deposition of MoS2 via electrophoretic process. The method can be applied both to simple metallic flat nanostructures and to complex 3D metallic structures both comprising nanoholes. The deposition method allows the decoration of large ordered arrays of plasmonic structures with single or few layers of MoS2. We show that the plasmonic field generated by the nanohole can interact significantly with the 2D layer, thus representing an ideal system for hybrid 2D-Material/Plasmonic investigation. The controlled and ordered integration of 2D materials on plasmonic nanostructures opens a pathway towards, for instance, enhanced light emission; strong coupling from plasmonic hybrid structures; hot electron generation; and sensors based on 2D materials.

physics.app-ph↗

arXiv2018

Hybrid plasmonic nanostructures based on controlled integration of MoS2 flakes on metallic nanoholes

Here, we propose an easy and robust strategy for the versatile preparation of hybrid plasmonic nanopores by means of controlled deposition of single flakes of MoS2 directly on top of metallic holes. The device is realized on silicon nitride commercial membranes and can be further refined by TEM or FIB milling to achieve the passing of molecules or nanometric particles through a pore. Importantly, we show that the plasmonic enhancement provided by the nanohole is strongly accumulated in the 2D nanopore, thus representing an ideal system for single-molecule sensing and sequencing in a flow-through configuration. Here, we also demonstrate that the prepared 2D material can be decorated with metallic nanoparticles that can couple their resonance with the nanopore resonance to further enhance the electromagnetic field confinement at the nanoscale level. This method can be applied to any gold nanopore with a high level of reproducibility and parallelization; hence, it can pave the way to the next generation of solid-state nanopores with plasmonic functionalities. Moreover, the controlled/ordered integration of 2D materials on plasmonic nanostructures opens a pathway towards new investigation of the following: enhanced light emission; strong coupling from plasmonic hybrid structures; hot electron generation; and sensors in general based on 2D materials. Nanopore

physics.app-ph↗