Large-Area Plasmonics on Self-Organized Wrinkled Nanopatterns

The focus of my PhD project consisted in the development of self-organized, large area, industrially scalable physical methods based on wrinkling instabilities to nanopattern and functionalize tunable plasmonic polymeric polydimetilsyloxane (PDMS) and solid-state glass surfaces, both transparent, non-toxic and cheap materials, for applications of significant technological interest in photonics and bio-sensing

Highly efficient sequestration of aqueous lead on nanostructured calcite substrates

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 (11.0) and (21.12) terminations. In situ AFM imaging during the exposure of such modified calcite surfaces to PbCl2 aqueous solution reveals that the nanostructured calcite surface promotes the uptake of Pb. In addition, we observed the progressive smoothing of the highly reactive calcite facet terminations and the formation of Pb-bearing precipitates elongated in registry with the underlying nanopattern. By SEM–EDS analysis we quantified a remarkable 500% increase of the Pb uptake rate, up to 0.5 atomic weight % per hour, on the nanorippled calcite in comparison to its freshly cleaved (10.4) surfaces. These results suggest that nanostructurated calcite surfaces can be used for developing future systems for lead sequestration from polluted waters.Universidad Técnica de AmbatoJuan de la Cierva-Formación postdoctoral contract (ref. FJC2018–035820- I)Spanish Ministry of ScienceMinistero dell’Università e della Ricerca (MUR)National Recovery and Resilience Plan (NRRP)Mission 4 Component 2 Investment 1.3 - Call for tender No. 1561 of 11.10.2022The European Union – NextGenerationEU • Award Number: Project code PE0000021Concession Decree No. 1561 of 11.10.2022 adopted by Ministero dell’Università e della Ricerca (MUR)CUP D33C22001300002 Project title “Network 4 Energy Sustainable Transition – NEST”. FBdM acknowledges support by UNIGE in the framework of BIPE2020 program and technical suppor

Self-Organized Tailoring of Faceted Glass Nanowrinkles for Organic Nanoelectronics

Self-organized wrinkled templates are homogeneously fabricated over a large area (cm2) glass substrates by defocused ion beam irradiation, demonstrating the capability to induce and modify at will the out-of-plane tilt of the nanofacets with selected slope. We identify a region of morphological instability which leads to faceting for incidence angles of the ion beam with respect to the surface, \u3b8, in the range 15\ub0 64 \u3b8 64 45\ub0, while for normal incidence, \u3b8 = 0\ub0, and for grazing incidence at about 55\u201360\ub0 a flat morphology is achieved. The crucial parameter which controls the slope of the sawtooth profile is the local ion beam incidence angle on the facets which corresponds to the maximum erosion velocity. For \u3b8 = 30\ub0, improved lateral order of the templates is found which can be exploited for the anisotropic confinement of functional layers. Here, we highlight the crucial role of the 1D nanopatterned template in driving the anisotropic crystallization of spun-cast conductive polymer thin films in registry with the faceted nanogrooves. In response, anisotropic electrical transport properties of the nanopatterned film are achieved with overall improvement higher than 60% with respect to a flat reference, thus showing the potential of such transparent large-area templates in nanoelectronics, optoelectronics, and biosensing

Free-standing plasmonic nanoarrays for leaky optical waveguiding and sensing

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 Si3N4 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. This possibility allowed us to select sharp waveguided modes supporting strong near-field amplification, extending for hundreds of nanometres out of the grating and enabling versatile biosensing applications. We demonstrate the potential of this flat-optics platform by devising a proof-of-concept nanofluidic refractive index sensor exploiting the long-range waveguided mode operating at the sub-picoliter scale. This free-standing device configuration, that could be further engineered at the nanoscale, highlights the strong potential of flat-optics nanoarrays in optofluidics and nanofluidic biosensing. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreemen

Infrared Plasmonics via Self-Organized Anisotropic Wrinkling of Au/PDMS Nanoarrays

Polydimethylsiloxane (PDMS) templates are nanopatterned over large areas to form uniaxial wrinkles by air plasma treatment on prestretched samples. Ripple-like structures with tunable height/width aspect ratio are so achieved. The anisotropic uniaxial PDMS modulations represent an ideal platform for the confinement of plasmonic nanowire (NW) arrays by grazing angle Au thermal deposition. This self-organized fabrication method is suitable to be scaled to the industrial level as a single step maskless process. The flexible NW arrays show monodisperse width distribution and exhibit strongly dichroic optical properties. Localized surface plasmon resonances (LSPR) of dipolar and multipolar character are excited when light is linearly polarized orthogonally to the NW major axis. The LSPR wavelength can be easily tuned across a remarkably large spectral range from 600 to 1200 nm by engineering the NW width and the PDMS ripple morphology. The PDMS/Au NW nanocomposite material also shows relevant performance as a transparent flexible electrode with sheet resistance on the order of 15 Omega/sq, a figure of merit which is competitive with the best transparent conductive oxides

Wavelength-Dependent Plasmonic Photobleaching of Dye Molecules by Large-Area Au Nanostripe Arrays

The development of clean light-harvesting platforms and technologies is crucial in view of the urgent energy and environmental global challenges. Plasmonic nanoparticles show great promise in light-harvesting applications, but their fabrication is typically constrained to small-area laboratory-scale methods or to highly polluting wet chemistry approaches that are not suitable for environmental applications such as waste water recycling. In this work, we propose a self-organized method to fabricate largearea (cm(2), industrially scalable up to m(2)) plasmonic templates. Ordered Au nanostripe arrays supported on cheap, nontoxic sodalime glass substrates are prepared, showing a tunable plasmonic response. We demonstrate enhanced photochemical reactivity and photobleaching of highly polluting methylene blue molecules promoted by this self-organized plasmonic platform. We investigate this effect by tailoring the spectral overlap between the molecule absorption band and the plasmon resonance and by tuning the monochromatized excitation wavelength. This kind of study is completely lacking in the literature for big molecules with optical absorption bands in the visible range. We demonstrate the dominant role of plasmon-enhanced near-field optical effects over hot-carrier injection in amplifying photodissociation of colored dye molecules, thus paving the way to the engineering and optimization of light-harvesting platforms for waste water treatment, dye molecule sensing devices, and a broad range of other light-harvesting applications