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2. Has the chemical contribution a secondary role in SERS?

Author

Hernandez, Luis A. Guerra, Reynoso, Andres A., and Fainstein, Alejandro

Subjects
Physics - Optics, Condensed Matter - Other Condensed Matter
Abstract

It is an established understanding that the electromagnetic contribution (the plasmon-mediated enhancement of the laser and scattered local electromagnetic fields) is the main actor in Surface Enhanced Raman Scattering (SERS), with the so-called chemical (molecule-related) contribution assuming only, if any, a supporting role. The conclusion of our comprehensive resonant study of a broad range of nanosphere lithography based metallic substrates, with covalently attached 4-mercaptobenzoic acid monolayers used as probe (molecules non-resonant in solution), is that this accepted understanding needs to be revised. We present a detailed resonant SERS study of Metal-film over nanosphere (MFON) substrates done both by scanning the laser wavelength, and by tuning the plasmon response through the nanosphere diameter. Far and local field properties are characterized through measures of optical reflectivity and SERS efficiency, respectively, and are supported by numerical simulations. We demonstrate that the SERS efficiency depends indeed on the electromagnetic mechanism, determined by the plasmonic response of the system, but we observe that it is also strongly defined by a chemical resonant contribution related to a metal-to-ligand electronic transition of the covalently bound probe molecule. Optimum amplification occurs when the plasmon modes intersect with the ligand-to-metal chemical resonance, contributing synergically both mechanisms together. The same general trend is observed for other nanosphere lithography based substrates, including sphere-segment void cavities and hexagonally ordered triangular nanoparticles, using both Ag or Au as the plasmonic metal, and also with a commercial substrate (Klarite). We conclude that a deep understanding of both the electromagnetic and chemical mechanisms is necessary to fully exploit these substrates for analytical applications.

Published
2023
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4. Critical coupling to Tamm plasmons

Author

Auguie, Baptiste, Bruchhausen, Axel, and Fainstein, Alejandro

Subjects
Physics - Optics
Abstract

The conditions of critical coupling of light to Tamm plasmons are investigated with comprehensive numerical simulations, highlighting the parameters that maximise absorption of incident light in the metal layer. The asymmetric response in reflection and absorption with respect to the direction of incidence is discussed, the two cases yielding different optimal coupling conditions. These findings are relevant for the design of optimised Tamm structures, particularly in applications such as narrow-band thermal emitters, field-enhanced spectroscopy and refractive-index sensing.

Published
2014
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6. Optics in South America: introduction

Author

Wiederhecker, Gustavo S., primary, Cavalcanti, S. B., additional, Fontes, Adriana, additional, Garcia-Sucerquia, Jorge, additional, Perez, Dario, additional, Vera, Esteban, additional, Bragas, Andrea, additional, de Matos, Christiano, additional, Fainstein, Alejandro, additional, Felinto, Daniel, additional, Milori, Debora M. B. P., additional, and Walborn, Stephen P., additional

Published
2023
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9. Electrochemical modulation for signal discrimination in Surface Enhanced Raman Scattering (SERS)

Author

Cortes, Emiliano, Etchegoin, Pablo G., Le Ru, Eric C., Fainstein, Alejandro, Vela, Maria E., and Salvarezza, Roberto C.

Subjects
Electrochemical reactions -- Research, Signal processing -- Methods, Raman effect -- Research, Surface chemistry -- Research, Digital signal processor, Chemistry
Abstract

Electrochemical modulation to induce controlled fluctuations in SERS signals is introduced as a method to discriminate and isolate different contributions to the spectra. The modulation--which can be changed in potential range, amplitude, and frequency--acts as a controllable 'switch' to turn on, off, or change specific Raman signals which can then be correlated within the spectra by different fluctuation analysis techniques. Principal component analysis (PCA), either by itself or assisted by fast fourier transform (FFT) prefiltering, are shown to provide viable tools to isolate the different components of the spectra. Electrochemical modulation provides, therefore, a technique to study complex cases of coad-sorption, and resolve problems of spectral congestion in SERS signals. 10.1021/ac101152t

Published
2010

10. Polariton-driven phonon laser

Author

Chafatinos, Dimitri Lisandro, Kuznetsov, Alexander, Anguiano, Sebastian, Bruchhausen, Axel Emerico, Reynoso, Andres Alejandro, Biermann, Klaus, Santos, Paulo, and Fainstein, Alejandro

Subjects
purl.org/becyt/ford/1 [https], BEC, purl.org/becyt/ford/1.3 [https], phonon, polaritons, laser
Abstract

Efficient generation of phonons is an important ingredient for a prospective electrically-driven phonon laser. Hybrid quantum systems combining cavity quantum electrodynamics and optomechanics constitute a novel platform with potential for operation at the extremely high frequency range (30–300 GHz). We report on laser-like phonon emission in a hybrid system that optomechanically couples polariton Bose-Einstein condensates (BECs) with phonons in a semiconductor microcavity. The studied system comprises GaAs/AlAs quantum wells coupled to cavity-confined optical and vibrational modes. The non-resonant continuous wave laser excitation of a polariton BEC in an individual trap of a trap array, induces coherent mechanical self-oscillation, leading to the formation of spectral sidebands displaced by harmonics of the fundamental 20 GHz mode vibration frequency. This phonon “lasing” enhances the phonon occupation five orders of magnitude above the thermal value when tunable neighbor traps are red-shifted with respect to the pumped trap BEC emission at even harmonics of the vibration mode. These experiments, supported by a theoretical model, constitute the first demonstration of coherent cavity optomechanical phenomena with exciton polaritons, paving the way for new hybrid designs for quantum technologies, phonon lasers, and phonon-photon bidirectional translators. Fil: Chafatinos, Dimitri Lisandro. 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; Argentina Fil: Kuznetsov, Alexander. Paul Drude Institut; Alemania Fil: Anguiano, Sebastian. 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; Argentina Fil: Bruchhausen, Axel Emerico. 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; Argentina Fil: Reynoso, Andres Alejandro. 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; Argentina Fil: Biermann, Klaus. Paul Drude Institut; Alemania Fil: Santos, Paulo. Paul Drude Institut; Alemania Fil: Fainstein, Alejandro. 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; Argentina

Published
2020

11. Exploring three-dimensional nanosystems with Raman spectroscopy: Methylene blue adsorbed on thiol and sulfur monolayers on gold

Author

Tognalli, Nicolas G., Fainstein, Alejandro, Vericat, Carolina, Vela, Maria E., and Salvarezza, Roberto C.

Subjects
Raman spectroscopy -- Research, Gold compounds -- Spectra, Raman effect -- Research, Chemicals, plastics and rubber industries
Abstract

Resonant Raman and surface-enhanced Raman scattering (SERS) spectroscopies, complemented with scanning tunnel microscopy and electrochemical techniques are used to obtain information about the amount and spatial distribution of methylene blue (MB) molecules immobilized on sulfur and four ultrathin molecular alkanethiolate films. The decrease in the SERS intensity as a function of distance for the rough Au electrodes is used to locate the average position of the MB species with respect to the Au substrate.

Published
2006

16. Monitoring the electrochemistry of single molecules by surface-enhanced raman spectroscopy

Author

Cortes, Emiliano, Etchegoin, Pablo G., Le Ru, Eric C., Fainstein, Alejandro, Vela, Maria E., and Salvarezza, Roberto C.

Subjects
Raman spectroscopy -- Usage, Electrochemistry -- Analysis, Chemistry
Abstract

The application of the bianalyte surface-enhanced Raman spectroscopy technique for studying the electrochemistry of different single molecules (SM) is explained. The methodology is shown to be extremely beneficial for the SM detection of any molecule, while providing better sensitivity and richness.

Published
2010

18. SPR Biosensing MUA/Poly-L-lysine Platform for the Detection of 2,4-Dinitrophenol as Small Molecule Model System

Author

Daza Millone, M. Antonieta, primary, Ramirez, Eduardo A., additional, Chain, Cecilia Y., additional, Crivaro, Andrea, additional, Romanin, David, additional, Rumbo, Martín, additional, Docena, Guillermo, additional, Cocco, Mauro D., additional, Pedano, María L., additional, Fainstein, Alejandro, additional, Montoya, Jorgelina, additional, Vela, María E., additional, and Salvarezza, R. C., additional

Published
2016
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19. Coupling between Light and Terahertz-Frequency Acoustic Phonons in Ferroelectric BaTiO3 /SrTiO3 Superlattices

Author

Bruchhausen, Axel Emerico, Fainstein, Alejandro, Tinte, Silvia Noemi, Soukiassian, A., Schlom, D. G., and Xi, X. X.

Subjects
purl.org/becyt/ford/1 [https], Ciencias Físicas, nanostructures, high-resolution ultraviolet Raman scattering, purl.org/becyt/ford/1.3 [https], multifunctional ferroelectrics, CIENCIAS NATURALES Y EXACTAS, Física de los Materiales Condensados, Óptica
Abstract

The acoustic phonons in epitaxial ferroelectric (BaTiO3 )n /(SrTiO3 )m superlattices (SLs) are investigated by high-resolution ultraviolet Raman scattering. The temperature dependence of the folded acoustic (FA) phonon Raman intensity through the ferroelectric transition is addressed. A comparison of this behavior between SLs with different number of ferroelectric BaTiO3 unit cells n and spacer SrTiO3 unit cells m is presented. A mechanism involving the strain modulation of the spatially varying ferroelectric polarization is introduced to explain the temperature dependence of the FA phonon scattering. The temperature dependence of the polarization can be derived from an analysis of the first-order optical phononspectra. Using this information, the observed temperature dependence of the whole set of SLs with different n can be consistently accounted for with the presented model. Atomistic shell-model simulations of the spatial pattern of the SL polarization are presented to explain the variation of the FA-spectral intensity for SLs with different m and the experimental fact that no high-order FA-replicas are observed. These results demonstrate the strong coupling between THz hypersound, charge, and light in these multifunctional nanoscale ferroelectrics. Fil: Bruchhausen, Axel Emerico. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; Argentina. University of Konstanz; Alemania Fil: Fainstein, Alejandro. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; Argentina Fil: Tinte, Silvia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina Fil: Soukiassian, A.. University Park; Estados Unidos Fil: Schlom, D. G.. Cornell University; Estados Unidos Fil: Xi, X. X.. Cornell University; Estados Unidos. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigaciones y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina

Published
2011

28. From Single to Multiple Ag-Layer Modification of Au Nanocavity Substrates: A Tunable Probe of the Chemical Surface-Enhanced Raman Scattering Mechanism

Author

Tognalli, Nicolás G., primary, Cortés, Emiliano, additional, Hernández-Nieves, Alexander D., additional, Carro, Pilar, additional, Usaj, Gonzalo, additional, Balseiro, Carlos A., additional, Vela, María E., additional, Salvarezza, Roberto C., additional, and Fainstein, Alejandro, additional

Published
2011
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31. Redox molecule based SERS sensors

Author

Tognalli, Nicolás G., primary, Scodeller, Pablo, additional, Flexer, Victoria, additional, Szamocki, Rafael, additional, Ricci, Alejandra, additional, Tagliazucchi, Mario, additional, Calvo, Ernesto J., additional, and Fainstein, Alejandro, additional

Published
2009
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34. Escape time of an acoustic nanocavity mode

Author

Pascual Winter, Maria Florencia, primary, Rozas, Guillermo, additional, Fainstein, Alejandro, additional, Jusserand, Bernard, additional, Perrin, Bernard, additional, and Lemaitre, Aristide, additional

Published
2008
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35. Photoelastic transduction in photo-phononic nanodevices

Author

Fainstein, Alejandro, primary, Jusserand, Bernard, additional, Pascual Winter, Maria Florencia, additional, Lanzillotti Kimura, Norberto Daniel, additional, Rozas, Guillermo, additional, Perrin, Bernard, additional, Huynh, Agnès, additional, and Lemaitre, Aristide, additional

Published
2008
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40. Raman Scattering in Resonant Cavities.

Author

Ascheron, Claus E., Duhm, Adelheid H., Cardona, Manuel, Merlin, Roberto, Fainstein, Alejandro, and Jusserand, Bernard

Abstract

The modification of the optical properties of matter due to photon confinement in optical microcavities has been an active field of research in the last ten years. This review addresses the problem of Raman scattering in these optically confining structures. Two completely different regimes exist and will be discussed here. Firstly, a situation in which the action of the microcavity is basically to enhance, and to spatially and spectrally confine, the photon field, but otherwise the light-matter interaction process remains unaltered. This is the case when the laser and scattered photon energies are well below those of the excitonic transitions in the structure, or when the coupling between the latter and the cavity mode can be treated in a "weak coupling" approximation. This regime will be labeled here as "optical resonant Raman scattering". And secondly, a "strong-coupling" regime in which exciton and cavity-photon modes cannot be treated separately, leading to coupled excitations, so-called cavity polaritons. In this second case, when the laser or scattered photons are tuned to the excitonic energies, and thus an electronic resonant Raman-scattering process is achieved, the Raman-scattering process has to be described in a fundamentally different way. This regime will be labeled as "cavity-polariton-mediated Raman scattering". The Chapter will begin, after a brief historical introduction, with a review of the fundamental properties of optical microcavities, and of the different strategies implemented to achieve double optical resonant Raman scattering in planar microcavities. A section will be then devoted to experimental results that highlight the different characteristics and potentialities of Raman scattering under optical confinement, including, in some detail, an analysis of the performance of these structures for Raman amplification. A subsequent section will present a series of research efforts devoted to the study of nanostructure phonon physics that rely on microcavities for Raman enhancement. In particular, emphasis will be given to recent investigations on acoustic cavities that parallel their optical counterparts but that, instead, confine hypersound in the GHz-THz range. The Chapter will then turn to a quite different topic, that of cavity-polariton-mediated scattering. The theory developed in the 1970s for bulk materials will be briefly introduced, and its modifications to account for photon confinement in planar structures will be addressed. Finally, a series of experiments that demonstrate the involvement of polaritons in the inelastic scattering of light in strongly coupled cavities will be reviewed. The Chapter will end with some conclusions and prospects for future developments on this subject. [ABSTRACT FROM AUTHOR]

Published
2006
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41. In Situ Raman Spectroscopy of Redox Species Confined in Self-Assembled Molecular Films

Author

G. Tognalli, Nicolás, Fainstein, Alejandro, Vericat, Carolina, E. Vela, María, and C. Salvarezza, Roberto

Abstract

In situ Raman spectroscopy and electrochemical experiments are used to study different methylene blue (MB) species immobilized in molecular films (sulfur, propanethiol, dodecanethiol, mercaptopropionic acid, and mercaptoundecanoic acid monolayers), self-assembled on SERS-active Au surfaces in aqueous electrolyte under potential control. The presence of three different MB species along reduction−oxidation cycles is inferred, irrespective of the nature of the molecular film. Residual Raman intensity in the spectroscopically silent leuco methylene blue (LMB) potential range demonstrate a dissimilar degree of connectivity for electron transfer between MB molecules and substrate depending on the spacer. In addition, the intensity of the Raman signal depends on the monolayer chemistry where hydrophobic and/or electrostatic interactions tend to stabilize the MB species against desorption from the molecular film driven by concentration gradients.

Published
2008
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42. Construcción y propiedades de sistemas moleculares ensamblados sobre superficies lisas, nanoestructuradas y nanopartículas

Author

Emiliano Cortés, Vela, María Elena, Fainstein, Alejandro, and Salvarezza, Roberto C.

Subjects
dimensiones, sistemas de sensado, Estructura Molecular, autoensamblado, fenómenos electroquímicos, Química, sistemas moleculares, Fenómenos Fisicoquímicos, Ciencias Exactas
Abstract

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 Exactas

Published
2013
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43. Películas delgadas nano-compuestas (nanopartícula metálica / matríz mesoporosa) con aplicaciones en espectroscopía Raman amplificada por superficies

Author

Martínez, Eduardo David, Soler-Illia, Galo Juan de Ávila Arturo, and Fainstein, Alejandro

Subjects
TECNOLOGÍA ELECTRÓNICA, TECNOLOGÍA DE MATERIALES, NANOTECNOLOGÍA, TECNOLOGÍA AVANZADA, TECNOLOGÍA QUÍMICA
Abstract

Tesis de Doctorado en Ciencia y Tecnología, Mención Química Dentro de la temática de este trabajo, aspectos adicionales como la estabilidad química y térmica de los depósitos metálicos, junto con el control de la morfología y estructura de los mismos, entre otras cuestiones, brindan la información experimental necesaria para la formulación de una metodología general orientada a lograr el control de las propiedades de interés tecnológico y otorgar una comprensión de las mismas dentro del campo conjunto de la ciencia de los materiales y la plasmónica. El conocimiento adquirido sobre la síntesis, la caracterización y las propiedades de los nanocompuestos PDMP-NPM representa una herramienta esencial para el desarrollo de dispositivos ópticos y electrónicos de base nanotecnológica, abriendo posibilidades y perspectivas de investigación en áreas multidisciplinarias de química inorgánica, fotónica y nano-electrónica. Es el espíritu de este trabajo contribuir con un conocimiento sustentado en la experimentación y en la discusión de los resultados en el marco de los desarrollos científicos actuales. Fil: Martínez, Eduardo David. Universidad Nacional de San Martín. Instituto de Investigaciones e Ingeniería Ambiental; Buenos Aires, Argentina.

Published
2013

44. The lifetime of interlayer breathing modes of few-layer 2H-MoSe 2 membranes.

Author

Soubelet P, Reynoso AA, Fainstein A, Nogajewski K, Potemski M, Faugeras C, and Bruchhausen AE

Abstract

A time-resolved observation of coherent interlayer longitudinal acoustic phonons in thin layers of 2H-MoSe2 is reported. A femtosecond pump-probe technique is used to investigate the evolution of the energy loss of these vibrational modes in a wide selection of MoSe2 flakes with different thicknesses ranging from bilayer up to the bulk limit. By directly analysing the temporal decay of the modes, we can clearly distinguish an abrupt crossover related to the acoustic mean free path of the phonons in a layered system, and the constraints imposed on the acoustic decay channels when reducing the dimensionality. For thicker samples, the main acoustic attenuation mechanism is attributed to the scattering of the acoustic modes with thermal phonons. For samples thinner than ∼20 molecular layers, the predominant damping mechanism is ascribed to the effects of surface asperity. Losses intrinsic to the low dimensionality of single or few layer materials impose critical limitations for their use in optomechanical and optoelectronic devices.

Published
2019
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