Publications by authors named "Maria C Giordano"

The strategic field of renewable energy production and storage requires novel nanoscale platforms that can feature competitive solar energy conversion properties. Photochemical reactions that promote energy storage, such as water splitting and oxygen-hydrogen evolution reactions, play a crucial role in this context. Here, we demonstrate a novel photoelectrochemical device based on large-area (cm) self-organized Au nanowire (NW) arrays, uniformly coated with ultrathin TiO films.

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Thermal scanning-probe lithography (t-SPL) is a high-resolution nanolithography technique that enables the nanopatterning of thermosensitive materials by means of a heated silicon tip. It does not require alignment markers and gives the possibility to assess the morphology of the sample in a noninvasive way before, during, and after the patterning. In order to exploit t-SPL at its peak performances, the writing process requires applying an electric bias between the scanning hot tip and the sample, thereby restricting its application to conductive, optically opaque, substrates.

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Following defocused ion beam sputtering, large area highly corrugated and faceted nanoripples are formed on calcite (10.4) faces in a self-organized fashion. High resolution atomic force microscopy (AFM) imaging reveals that calcite ripples are defined by facets with highly kinked (11.

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Thin-film organic photovoltaic (OPV) devices represent an attractive alternative to conventional silicon solar cells due to their lightweight, flexibility, and low cost. However, the relatively low optical absorption of the OPV active layers still represents an open issue in view of efficient devices that cannot be addressed by adopting conventional light coupling strategies derived from thick PV absorbers. The light coupling to thin-film solar cells can be boosted by nanostructuring the device interfaces at the subwavelength scale.

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Article Synopsis
  • Recent advancements in photonic technologies highlight the importance of all-optical dynamic control for complex photonic elements, especially in integrated photonics and metasurfaces.
  • The study presents a design for a two-dimensional bull's eye cavity made within a unique optically-active polymer that allows for the coupling of two surface resonant modes through free-space illumination.
  • Dynamic control of resonant modes is achieved by changing the orientation of birefringence using a polarized laser, resulting in reversible shifts in resonant wavelengths across a 2 nm range.
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Novel light harvesting platforms and strategies are crucial to develop renewable photon to energy conversion technologies that overcome the current global energy and environmental challenges. Two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductor layers are particularly attractive for photoconversion applications but new ultra-compact photon harvesting schemes are urgently required to mitigate their poor photon absorption properties. Here, we propose a flat-optics scheme based on nanogrooved ultra-thin MoS layers conformally grown onto large area (cm scale) nanopatterned templates.

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Flat optics nanogratings supported on thin free-standing membranes offer the opportunity to combine narrowband waveguided modes and Rayleigh anomalies for sensitive and tunable biosensing. At the surface of high-refractive index SiN membranes we engineered lithographic nanogratings based on plasmonic nanostripes, demonstrating the excitation of sharp waveguided modes and lattice resonances. We achieved fine tuning of these optical modes over a broadband Visible and Near-Infrared spectrum, in full agreement with numerical calculations.

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Highly porous Germanium surfaces with uniformly distributed columnar nanovoid structures are fabricated over a large area (wafer scale) by large fluence Snirradiation through a thin silicon nitride layer. The latter represents a one-step highly reproducible approach with no material loss to strongly increase photon harvesting into a semiconductor active layer by exploiting the moth-eye antireflection effect. The ion implantation through the nitride cap layer allows fabricating porous nanostructures with high aspect ratio, which can be tailored by varying ion fluence.

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Permalloy NiFe is one of the key magnetic materials in the field of magnonics. Its potential would be further unveiled if it could be deposited in three dimensional (3D) architectures of sizes down to the nanometer. Atomic Layer Deposition, ALD, is the technique of choice for covering arbitrary shapes with homogeneous thin films.

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Nanofabrication of flat optic silica gratings conformally layered with two-dimensional (2D) MoS is demonstrated over large area (cm), achieving a strong amplification of the photon absorption in the active 2D layer. The anisotropic subwavelength silica gratings induce a highly ordered periodic modulation of the MoS layer, promoting the excitation of Guided Mode Anomalies (GMA) at the interfaces of the 2D layer. We show the capability to achieve a broadband tuning of these lattice modes from the visible (VIS) to the near-infrared (NIR) by simply tailoring the illumination conditions and/or the period of the lattice.

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Flat optics nanoarrays based on few-layer MoS2 are homogeneously fabricated over large-area (cm2) transparent templates, demonstrating effective tailoring of the photon absorption in two-dimensional (2D) transition-metal dichalcogenide (TMD) layers. The subwavelength subtractive re-shaping of the few-layer MoS2 film into a one-dimensional (1D) nanostripe array results in a pronounced photonic anomaly, tunable in a broadband spectral range by simply changing the illumination conditions (or the lattice periodicity). This scheme promotes efficient coupling of light to the 2D TMD layers via resonant interaction between the MoS2 excitons and the photonic lattice, with subsequent enhancement of absorption exceeding 400% relative to the flat layer.

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Article Synopsis
  • Bidirectional nanoantennas enable advanced functions at the nanoscale, particularly for color routing in compact optical systems.
  • The new approach uses a simpler bimetallic structure to create effective nanoantennas without complex designs, employing a self-organized technique for large-area fabrication.
  • The developed nanoantennas show impressive performance in broadband color routing and light scattering, making them viable for applications in telecommunications and optical sensing.
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At terahertz (THz) frequencies, scattering-type scanning near-field optical microscopy (s-SNOM) based on continuous wave sources mostly relies on cryogenic and bulky detectors, which represents a major constraint for its practical application. Here, we devise a THz s-SNOM system that provides both amplitude and phase contrast and achieves nanoscale (60-70nm) in-plane spatial resolution. It features a quantum cascade laser that simultaneously emits THz frequency light and senses the backscattered optical field through a voltage modulation induced inherently through the self-mixing technique.

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  • The study shows how wrinkling patterns form on soft materials when thin films are under compression on flexible substrates, particularly using a solid-state substrate modified by ion beams.
  • When the substrate is heated near its glass transition temperature, the formation of these wrinkles significantly accelerates the growth of self-organized nanopatterns, leading to high-aspect-ratio ripples ideal for nanostructure fabrication.
  • The resulting structures can be used to create large-area arrays of gold nanostripes with unique optical and electrical properties, making them valuable for applications in nanophotonics, biosensing, and optoelectronics.
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Near-field imaging with terahertz (THz) waves is emerging as a powerful technique for fundamental research in photonics and across physical and life sciences. Spatial resolution beyond the diffraction limit can be achieved by collecting THz waves from an object through a small aperture placed in the near-field. However, light transmission through a sub-wavelength size aperture is fundamentally limited by the wave nature of light.

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Article Synopsis
  • - Self-organized nanowire arrays are created on glass templates through angled Au deposition, leading to large area, semi-transparent structures with high electrical conductivity comparable to top transparent conductive oxides.
  • - The nanowires exhibit localized surface plasmon (LSP) resonances, which can be tuned for light in the visible to near-infrared spectrum and are activated by light polarized perpendicular to the wires, functioning well as multifunctional nanoelectrodes.
  • - Electrical percolation during the growth of these nanoelectrodes reveals a universal scaling of the percolation rate on flat surfaces, while nanopatterned templates show variations due to a shadowing effect that enhances the connectivity of 1D Au nanowires
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  • The study explores the SERS efficiency of arrays made from self-organized gold (Au) nanocrescents on polystyrene nanospheres.
  • A significant SERS emission in the visible spectrum occurs due to the excitation of a localized surface plasmon resonance along the short axis of the nanocrescents, achieving SERS signal amplifications around 10^3 times compared to a flat gold film.
  • The researchers investigate how changing the amount of metal on the polymer spheres affects the plasmonic response, demonstrating that the SERS emission can be tailored by modifying the shape of the nanocrescents and highlighting the role of satellite nanoclusters in enhancing the resonances.
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Gold nanospheres have been manipulated by atomic force microscopy on a rippled glass surface produced by ion beam sputtering and coated with an ultrathin (10 nm thick) graphitic layer. This substrate is characterized by irregular wavy grooves running parallel to a preferential direction. Measurements in ambient conditions show that the motion of the nanoparticles is confined to single grooves ('channels'), along which the particles move till they are trapped by local bottlenecks.

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  • Gold nanoparticles on nano-ripple quartz substrates were examined using spectroscopic Mueller matrix ellipsometry, revealing their anisotropic optical properties.
  • The optical response varies based on the direction: perpendicular components show localized plasmon resonance, while parallel components exhibit strong infrared resonances due to closely aligned nanoparticles.
  • The tilt of the gold nanoparticles, formed at an oblique angle, leads to a unique anisotropic plasmonic response, making these structures effective as a plasmonic nanowired grid polarizer.
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The expression pattern of estrogen receptor (ER) isoforms in normal and tumor thyroid tissues is still controversial and poor defined, therefore, a more detailed study of the distribution of these molecules is needed. Most discrepancies might be due to the methods utilized. We studied the expression of ER isoforms in human papillary thyroid carcinoma (PTC), in fine-needle aspiration biopsy-derived specimens, and in cells, using more accurate techniques, such as laser-capture microdissection, real-time quantitative PCR, and Western blot.

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Background: The consequences of low incidence of penetrating injuries in Europe and of the increasing in nonoperative management of blunt trauma are a decrease in surgeons' confidence for managing traumatic injuries. The Corso Teorico Pratico di Chirurgia del Politrauma was developed as model for teaching operative trauma techniques. The aim of this retrospective study is to evaluate the effectiveness of the course and compare it with other similar courses.

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