Construcción y propiedades de sistemas moleculares ensamblados sobre superficies lisas, nanoestructuradas y nanopartículas

El presente trabajo de Tesis abarca la construcción y estudio de propiedades fisicoquímicas de distintas plataformas con potenciales aplicaciones a sistemas de sensado. Sustratos metálicos de distinta dimensionalidad (3D, 2D, 0D) en conjunto con sistemas moleculares (quimisorbidos o fisisorbidos) acoplados a métodos de detección (ópticos y/o eléctricos) constituyen la base estructural de este trabajo. A lo largo de numerosos ejemplos, que van desde autoensamblados moleculares hasta moléculas individuales, estudiaremos la interacción molécula-superficie para cada uno de los casos con la intención de comprender, desde un punto de vista microscópico, distintos fenómenos que ocurren en dichas interfaces. En todos estos casos demostramos como el estudio en la nanoescala de distintas problemáticas interfaciales permite optimizar y potenciar distintas plataformas y/o mecanismos de sensado. Los resultados presentados en este trabajo de Tesis Doctoral contribuyen a la comprensión de fenómenos moleculares, plasmónicos y electroquímicos para el desarrollo de nuevos métodos de detección ultrasensible de moléculas.This Ph.D. thesis is aimed to study the construction and physicochemical properties of different platforms that can be potentially used as sensing systems. Metal substrates of different dimensionality (3D, 2D, 0D) together with molecular systems (chemisorbed or physisorbed) coupled to detection methods (optical and/or electrical) are the structural basis of this work. Through numerous examples -ranging from molecular self-assembled to individual molecules- we are going to study the molecule-surface interaction in an attempt to understand, from a microscopic point of view, different phenomena occurring at these interfaces. In all these cases, we demonstrated how the nanoscale approaches to different interfacial problems can optimize and enhance multiple platforms and/or sensing mechanisms. The results presented in the present work contributes to a better understanding of molecular, plasmonic and electrochemical phenomena in order to develop new methods for ultrasensitive detection of molecules.Facultad de Ciencias Exacta

Multiplication of the orbital angular momentum of phonon polaritons via sublinear dispersion

Optical vortices (OVs) promise to greatly enhance optical information capacity via orbital angular momentum (OAM) multiplexing. The need for on-chip integration of OAM technologies has prompted research into subwavelength-confined polaritonic OVs. However, the topological order imprinted by the structure used for the transduction from free-space beams to surface polaritons is inherently fixed after fabrication. Here, we overcome this limitation via dispersion-driven topological charge multiplication. We switch the OV topological charge within a small $\sim 3 \%$ frequency range by leveraging the strong sublinear dispersion of low-loss surface phonon polaritons (SPhP) on silicon carbide membranes. Applying the Huygens principle we quantitatively evaluate the topological order of the experimental OVs detected by near-field imaging. We further explore the deuterogenic effect, which predicts the coexistence of multiple topological charges in higher-order polaritonic OVs. Our work demonstrates a viable method to manipulate the topological charge of polaritonic OVs, paving the way for the exploration of novel OAM-enabled light-matter interactions at mid-infrared frequencies

Engineering gallium phosphide nanostructures for efficient nonlinear photonics and enhanced spectroscopies

Optical resonances arising from quasi-bound states in the continuum (QBICs) have been recently identified in nanostructured dielectrics, showing ultrahigh quality factors accompanied by very large electromagnetic field enhancements. In this work, we design a periodic array of gallium phosphide (GaP) elliptical cylinders supporting, concurrently, three spectrally separated QBIC resonances with in-plane magnetic dipole, out-of-plane magnetic dipole, and electric quadrupole characters. We numerically explore this system for second-harmonic generation and degenerate four-wave mixing, demonstrating giant per unit cell conversion efficiencies of up to ∼2 W-1 and ∼60 W-2, respectively, when considering realistic introduced asymmetries in the metasurface, compatible with current fabrication limitations. We find that this configuration outperforms by up to more than four orders of magnitude the response of low-Q Mie or anapole resonances in individual GaP nanoantennas with engineered nonlinear mode-matching conditions. Benefiting from the straight-oriented electric field of one of the examined high-Q resonances, we further propose a novel nanocavity design for enhanced spectroscopies by slotting the meta-atoms of the periodic array. We discover that the optical cavity sustains high-intensity fields homogeneously distributed inside the slot, delivering its best performance when the elliptical cylinders are cut from end to end forming a gap, which represents a convenient model for experimental investigations. When placing an electric point dipole inside the added aperture, we find that the metasurface offers ultrahigh radiative enhancements, exceeding the previously reported slotted dielectric nanodisk at the anapole excitation by more than two orders of magnitude.Fil: Moretti, Gianni Quimey. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Cortés, Emiliano. Ludwig Maximilians Universitat; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maier, Stefan A.. Ludwig Maximilians Universitat; Alemania. Imperial College London; Reino UnidoFil: Bragas, Andrea Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Grinblat, Gustavo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Resonant Far- to Near-Field Channeling in Synergetic Multiscale Antennas

Enhancing light-molecule interactions requires the efficient transfer of energy between the laboratory macroscale and the molecule nanoscale. Multiscale designs have been proposed as a means to efficiently connect these two worlds. Metallic sphere-segment void (SSV) cavities constitute plasmonic substrates in which light wavelength scale cavity-like modes and nanoscale roughness operate in conjunction as a multiscale antenna to provide larger surface-enhanced Raman scattering efficiency than the two mechanisms considered separately. We study the selective resonant coupling to cavity modes with different spatial distributions in SSV arrays with tailored nanoscale roughness. Cavity modes that are spatially more confined to the surface are demonstrated to lead to more efficient channeling of energy from the far to the near field, a synergy that scales with the degree of roughness. Finite-element modeling of the spatially varying local fields in rough SSV arrays allows for a microscopic description of the results, opening promising paths for the design of spatially and spectrally optimized multiscale antennas for efficient sensing with far- to near-field channeling of light.Fil: Guerra Hernandez, Luis Alfonso. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Huidobro, Paloma A.. Imperial College London; Reino UnidoFil: Cortés, Emiliano. Ludwig Maximilians Universitat; AlemaniaFil: Maier, Stefan A.. Ludwig Maximilians Universitat; AlemaniaFil: Fainstein, Alejandro. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentin

Direct Detection of Optical Forces of Magnetic Nature in Dielectric Nanoantennas

Optical forces on nanostructures are usually characterized by their interaction with the electric field component of the light wave, given that most materials present negligible magnetic response at optical frequencies. This is not the case however of a high-refractive-index dielectric nanoantenna, which has been recently shown to efficiently support both electric and magnetic optical modes. In this work, we use a photoinduced force microscopy configuration to measure optically induced forces produced by a germanium nanoantenna on a surrounding silicon near-field probe. We reveal the spatial distribution, character, and magnitude of the generated forces when exciting the nanoantenna at its anapole state condition. We retrieve optical force maps showing values of up to 20 pN, which are found to be mainly magnetic in nature, according to our numerical simulations. The results of this investigation open new pathways for the study, detection, and generation of magnetic light forces at the nanometer scale.Fil: Poblet, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Li, Yi. Southern University Of Science And Technology; ChinaFil: Cortés, Emiliano. Ludwig Maximilians Universitat; AlemaniaFil: Maier, Stefan A.. Ludwig Maximilians Universitat; AlemaniaFil: Grinblat, Gustavo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Bragas, Andrea Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Anti Stokes Thermometry of Plasmonic Nanoparticle Arrays

Metallic nanoparticles possess strong photothermal responses, especially when illuminated as ensembles due to collective effects. However, accurately quantifying the temperature increase remains a significant challenge, impeding progress in several applications. Anti Stokes thermometry offers a promising solution by enabling direct and non-invasive temperature measurements of the metal without the need for labeling or prior calibration. While Anti Stokes thermometry is successfully applied to individual nanoparticles, its potential to study light-to-heat conversion with plasmonic ensembles remains unexplored. In this study, the theoretical framework and the conditions that must be fulfilled for applying Anti Stokes thermometry to ensembles of nanoparticles are discussed. Then, this technique is implemented to measure the light-induced heating of square arrays of Au nanodisks. The obtained temperature measurements are validated using wavefront microscopy, demonstrating excellent agreement between the two thermometry methods. These results showcase the extension of Anti Stokes thermometry to plasmonic ensembles, highlighting its potential for implementation in the diverse photothermal applications involving these systems

Introducing a Symmetry-Breaking Coupler into a Dielectric Metasurface Enables Robust High-Q Quasi-BICs

Dielectric metasurfaces supporting quasibound states in the continuum (quasi-BICs) exhibit very high-quality factor resonances and electric field confinement. However, accessing the high-Q end of the quasi-BIC regime usually requires marginally distorting the metasurface design from a BIC condition, pushing the needed nanoscale fabrication precision to the limit. This work introduces a novel concept for generating high-Q quasi-BICs, which strongly relaxes this requirement by incorporating a relatively large perturbative element close to high-symmetry points of an undistorted BIC metasurface, acting as a coupler to the radiation continuum. This approach is validated by adding a ≈100 nm diameter cylinder between two reflection-symmetry points separated by a 300 nm gap in an elliptical disk metasurface unit cell, using gallium phosphide as the dielectric. It is found that high-Q resonances emerge when the cylindrical coupler is placed at any position between such symmetry points. This metasurface´s second harmonic generation capability in the optical range is further explored. Displacing the coupler as much as a full diameter from a BIC condition produces record-breaking normalized conversion efficiencies >102 W−1. The strategy of enclosing a disruptive element between multiple high-symmetry points in a BIC metasurface can be applied to construct robust high-Q quasi-BICs in many geometrical designs.Fil: Moretti, Gianni Quimey. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Tittl, Andreas. Ludwig Maximilians Universitat; AlemaniaFil: Cortés, Emiliano. Ludwig Maximilians Universitat; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maier, Stefan A.. Imperial College London; Reino Unido. Ludwig Maximilians Universitat; AlemaniaFil: Bragas, Andrea Veronica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Grinblat, Gustavo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin

Electrical control of single-photon emission in highly charged individual colloidal quantum dots

Electron transfer to an individual quantum dot promotes the formation of charged excitons with enhanced recombination pathways and reduced lifetimes. Excitons with only one or two extra charges have been observed and exploited for very efficient lasing or single-quantum dot light-emitting diodes. Here, by room-temperature time-resolved experiments on individual giant-shell CdSe/CdS quantum dots, we show the electrochemical formation of highly charged excitons containing more than 12 electrons and 1 hole. We report the control over intensity blinking, along with a deterministic manipulation of quantum dot photodynamics, with an observed 210-fold increase in the decay rate, accompanied by 12-fold decrease in the emission intensity, while preserving single-photon emission characteristics. These results pave the way for deterministic control over the charge state, and room-temperature decay rate engineering for colloidal quantum dot-based classical and quantum communication technologies

"La menesunda" (1965) y "La menesunda según Marta Minujín" (2015): procesos proyectuales de diseño

Las instalaciones artísticas contemporáneas trascienden el campo del arte para convertirse en objetos de diseño. Son proyectadas para alcanzar un objetivo; planificadas para cumplir una función. La ejecución de las mismas depende de dispositivos propios de disciplinas proyectuales como los diseños. El montaje de una obra en una época y lugar determinados y su re edición , años más tarde o en otra geografía, sólo se hace posible gracias a los relevamientos existentes de la misma. El análisis de la obra “ La Menesunda” (1965) de la artista plástica argentina Marta Minujín, y su remake “La Menesunda según Marta Minujín” (2015) nos permite enmarcar su proceso de producción artística como un “hacer” propio del diseño. Una mirada más amplia y la redefinición de la expresión “objetos de diseño” nos deja entender que no sólo el Diseño en Comunicación Visual o el Diseño Industrial son capaces de producirlos. Un proceso artístico, también es capaz de llegar a la elaboración de un objeto de diseño.Facultad de Bellas Arte