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This work presents a comprehensive review on gas sensors based on localized surface plasmon resonance (LSPR) phenomenon, including the theory of LSPR, the synthesis of nanoparticle-embedded oxide thin films, and strategies to enhance the sensitivity of these optical sensors, supported by simulations of the electromagnetic properties. The LSPR phenomenon is known to be responsible for the unique colour effects observed in the ancient Roman Lycurgus Cup and at the windows of the medieval cathedrals. In both cases, the optical effects result from the interaction of the visible light (scattering and absorption) with the conduction band electrons of noble metal nanoparticles (gold, silver, and gold–silver alloys). These nanoparticles are dispersed in a dielectric matrix with a relatively high refractive index in order to push the resonance to the visible spectral range. At the same time, they have to be located at the surface to make LSPR sensitive to changes in the local dielectric environment, the property that is very attractive for sensing applications. Hence, an overview of gas sensors is presented, including electronic-nose systems, followed by a description of the surface plasmons that arise in noble metal thin films and nanoparticles. Afterwards, metal oxides are explored as robust and sensitive materials to host nanoparticles, followed by preparation methods of nanocomposite plasmonic thin films with sustainable techniques. Finally, several optical properties simulation methods are described, and the optical LSPR sensitivity of gold nanoparticles with different shapes, sensing volumes, and surroundings is calculated using the discrete dipole approximation method.
Marco Rodrigues; Joel Borges; Cláudia Lopes; Rui Pereira; Mikhail Vasilevskiy; Filipe Vaz. Gas Sensors Based on Localized Surface Plasmon Resonances: Synthesis of Oxide Films with Embedded Metal Nanoparticles, Theory and Simulation, and Sensitivity Enhancement Strategies. Applied Sciences 2021, 11, 5388 .
AMA StyleMarco Rodrigues, Joel Borges, Cláudia Lopes, Rui Pereira, Mikhail Vasilevskiy, Filipe Vaz. Gas Sensors Based on Localized Surface Plasmon Resonances: Synthesis of Oxide Films with Embedded Metal Nanoparticles, Theory and Simulation, and Sensitivity Enhancement Strategies. Applied Sciences. 2021; 11 (12):5388.
Chicago/Turabian StyleMarco Rodrigues; Joel Borges; Cláudia Lopes; Rui Pereira; Mikhail Vasilevskiy; Filipe Vaz. 2021. "Gas Sensors Based on Localized Surface Plasmon Resonances: Synthesis of Oxide Films with Embedded Metal Nanoparticles, Theory and Simulation, and Sensitivity Enhancement Strategies." Applied Sciences 11, no. 12: 5388.
In this review, we discuss several fundamental processes taking place in semiconductor nanocrystals (quantum dots (QDs)) when their electron subsystem interacts with electromagnetic (EM) radiation. The physical phenomena of light emission and EM energy transfer from a QD exciton to other electronic systems such as neighbouring nanocrystals and polarisable 3D (semi-infinite dielectric or metal) and 2D (graphene) materials are considered. In particular, emission decay and FRET rates near a plane interface between two dielectrics or a dielectric and a metal are discussed and their dependence upon relevant parameters is demonstrated. The cases of direct (II–VI) and indirect (silicon) band gap semiconductors are compared. We cover the relevant non-radiative mechanisms such as the Auger process, electron capture on dangling bonds and interaction with phonons. Some further effects, such as multiple exciton generation, are also discussed. The emphasis is on explaining the underlying physics and illustrating it with calculated and experimental results in a comprehensive, tutorial manner.
Vladimir A. Burdov; Mikhail I. Vasilevskiy. Exciton-Photon Interactions in Semiconductor Nanocrystals: Radiative Transitions, Non-Radiative Processes, and Environment Effects. Applied Sciences 2021, 11, 497 .
AMA StyleVladimir A. Burdov, Mikhail I. Vasilevskiy. Exciton-Photon Interactions in Semiconductor Nanocrystals: Radiative Transitions, Non-Radiative Processes, and Environment Effects. Applied Sciences. 2021; 11 (2):497.
Chicago/Turabian StyleVladimir A. Burdov; Mikhail I. Vasilevskiy. 2021. "Exciton-Photon Interactions in Semiconductor Nanocrystals: Radiative Transitions, Non-Radiative Processes, and Environment Effects." Applied Sciences 11, no. 2: 497.
In this paper we study the formation of topological Tamm states at the interface between a semi-infinite one-dimensional (1D) photonic crystal and a metal. We show that when the system is topologically nontrivial there is a single Tamm state in each of the band gaps, whereas if it is topologically trivial the band gaps host no Tamm states. We connect the disappearance of the Tamm states with a topological transition from a topologically nontrivial system to a topologically trivial one. This topological transition is driven by the modification of the dielectric functions in the unit cell. Our interpretation is further supported by an exact mapping between the solutions of Maxwell's equations and the existence of a tight-binding representation of those solutions. We show that the tight-binding representation of the 1D photonic crystal, based on Maxwell's equations, corresponds to a Su-Schrieffer-Heeger–type model (SSH model) for each set of pairs of bands. By expanding this representation near the band edge we show that the system can be described by a Dirac-like Hamiltonian. It allows one to characterize the topology associated with the solution of Maxwell's equations via the winding number. In addition, for the infinite system, we provide an analytical expression for the photonic bands from which the band gaps can be computed.
J. C. G. Henriques; T. G. Rappoport; Y. V. Bludov; M. I. Vasilevskiy; N. M. R. Peres. Topological photonic Tamm states and the Su-Schrieffer-Heeger model. Physical Review A 2020, 101, 043811 .
AMA StyleJ. C. G. Henriques, T. G. Rappoport, Y. V. Bludov, M. I. Vasilevskiy, N. M. R. Peres. Topological photonic Tamm states and the Su-Schrieffer-Heeger model. Physical Review A. 2020; 101 (4):043811.
Chicago/Turabian StyleJ. C. G. Henriques; T. G. Rappoport; Y. V. Bludov; M. I. Vasilevskiy; N. M. R. Peres. 2020. "Topological photonic Tamm states and the Su-Schrieffer-Heeger model." Physical Review A 101, no. 4: 043811.
We describe exciton–polariton modes formed by the interaction between excitons in a 2D layer of a transition metal dichalcogenide embedded in a cylindrical microcavity and the microcavity photons. For this, an expression for the excitonic susceptibility of a semiconductor disk placed in the symmetry plane perpendicular to the axis of the microcavity is derived. Semiclassical theory provides dispersion relations for the polariton modes, while the quantum-mechanical treatment of a simplified model yields the Hopfield coefficients, measuring the degree of exciton–photon mixing in the coupled modes. The density of states (DOS) and its projection onto the photonic and the excitonic subspaces are calculated, taking monolayer MoS 2 embedded in a Si 3N 4 cylinder as an example. The calculated results demonstrate a strong enhancement for certain frequencies of the total and local DOS (and, consequently, of the spontaneous emission rate of a nearby point emitter, i.e., the Purcell effect) caused by the presence of the 2D layer.We describe exciton–polariton modes formed by the interaction between excitons in a 2D layer of a transition metal dichalcogenide embedded in a cylindrical microcavity and the microcavity photons. For this, an expression for the excitonic susceptibility of a semiconductor disk placed in the symmetry plane perpendicular to the axis of the microcavity is derived. Semiclassical theory provides dispersion relations for the polariton modes, while the quantum-mechanical treatment of a simplified model yields the Hopfield coefficients, measuring the degree of exciton–photon mixing in the coupled modes. The density of states (DOS) and its projection onto the photonic and the excitonic subspaces are calculated, taking monolayer MoS 2 embedded in a Si 3N 4 cylinder as an example. The calculated results demonstrate a strong enhancement for certain frequencies of the total and local DOS (and, consequently, of the spontaneous emission rate of a nearby point emitter, i.e., the Purcell effect) caused by the pre...
José Nuno S. Gomes; Carlos Trallero-Giner; Nuno M. R. Peres; Mikhail I. Vasilevskiy. Exciton–polaritons of a 2D semiconductor layer in a cylindrical microcavity. Journal of Applied Physics 2020, 127, 133101 .
AMA StyleJosé Nuno S. Gomes, Carlos Trallero-Giner, Nuno M. R. Peres, Mikhail I. Vasilevskiy. Exciton–polaritons of a 2D semiconductor layer in a cylindrical microcavity. Journal of Applied Physics. 2020; 127 (13):133101.
Chicago/Turabian StyleJosé Nuno S. Gomes; Carlos Trallero-Giner; Nuno M. R. Peres; Mikhail I. Vasilevskiy. 2020. "Exciton–polaritons of a 2D semiconductor layer in a cylindrical microcavity." Journal of Applied Physics 127, no. 13: 133101.
In this paper we show that graphene surface plasmons can be excited when an electromagnetic wave packet impinges on a single metal slit covered with graphene. The excitation of the plasmons localized over the slit is revealed by characteristic peaks in the absorption spectrum. It is shown that the position of the peaks can be tuned either by the graphene doping level or by the dielectric function of the material filling the slit. The whole system forms the basis for a plasmonic sensor when the slit is filled with an analyte.
Yu. V. Bludov; N. M. R. Peres; M. I. Vasilevskiy. Excitation of localized graphene plasmons by a metallic slit. Physical Review B 2020, 101, 075415 .
AMA StyleYu. V. Bludov, N. M. R. Peres, M. I. Vasilevskiy. Excitation of localized graphene plasmons by a metallic slit. Physical Review B. 2020; 101 (7):075415.
Chicago/Turabian StyleYu. V. Bludov; N. M. R. Peres; M. I. Vasilevskiy. 2020. "Excitation of localized graphene plasmons by a metallic slit." Physical Review B 101, no. 7: 075415.
The influence of O2 flow rate on the compositional, optical and electrical characteristics of silicon oxide (SiOx) thin films (x < 2) were studied in this work. The SiOx thin films were obtained by pulsed direct current (DC) magnetron sputtering (PMS) onto n-type Si wafers (and also on glass substrates) at a vacuum of 3 × 10−3 Pa. Rutherford backscattering spectrometry (RBS) was used to check the compositional elements of deposited films and its oxidized states were analysed via Fourier-transform infrared (FTIR) spectroscopy. The optical properties of as-deposited SiOx thin films were investigated from transmittance measurements at room temperature in the wavelength range of 250–800 nm. The obtained data reveal that the Urbach energy (a measure of the band tail extension, Eu) decreased from about 523 to 172 meV as the rate of oxygen gas flow increased. On the contrary, the optical energy band-gap (Eg) increased from 3.9 to 4.2 eV. Conduction and valance band positions (relative to the normal hydrogen electrode) were also evaluated. The observed behavior is probably associated with the degree of disorder and defects presented in the as-deposited SiOx thin films, probably due to the presence of newly inserted oxidized OnSiHy species resulting from some contamination with water vapor desorbed from the walls of the deposition vacuum chamber. After deposition of a gold top electrode, the electrical characteristics of the fabricated Au/SiOx/n-Si system (i.e., a metal/insulator/semiconductor structure—MIS) were studied via characteristic I-V curves and their dependence upon the O2 flow rate are reported. It was observed that the Au/SiOx/n-Si structure behaves like a Schottky-diode exhibiting a very good diode rectifying performance with a rectification ratio of at least 300 and up to 104, which refers to the samples produced with the lower and higher O2 flow rates, respectively. It was also found that the O2 flow rate influences the rectifying performance of the SiOx/n-structures since both the diode ideality factor, n, and the diode series-resistance, RS decreases with the increase of O2 content, possibly reflecting a closer approximation to a full stoichiometric condition.
Joaquim O. Carneiro; Filipe Machado; Luis Rebouta; Mikhail I. Vasilevskiy; Senen Lanceros-Méndez; Vasco Teixeira; Manuel F. Costa; Anura P. Samantilleke. Compositional, Optical and Electrical Characteristics of SiOx Thin Films Deposited by Reactive Pulsed DC Magnetron Sputtering. Coatings 2019, 9, 468 .
AMA StyleJoaquim O. Carneiro, Filipe Machado, Luis Rebouta, Mikhail I. Vasilevskiy, Senen Lanceros-Méndez, Vasco Teixeira, Manuel F. Costa, Anura P. Samantilleke. Compositional, Optical and Electrical Characteristics of SiOx Thin Films Deposited by Reactive Pulsed DC Magnetron Sputtering. Coatings. 2019; 9 (8):468.
Chicago/Turabian StyleJoaquim O. Carneiro; Filipe Machado; Luis Rebouta; Mikhail I. Vasilevskiy; Senen Lanceros-Méndez; Vasco Teixeira; Manuel F. Costa; Anura P. Samantilleke. 2019. "Compositional, Optical and Electrical Characteristics of SiOx Thin Films Deposited by Reactive Pulsed DC Magnetron Sputtering." Coatings 9, no. 8: 468.
We consider a hybrid structure formed by graphene and an insulating antiferromagnet, separated by a dielectric of thickness up to d 500 nm. When uncoupled, both graphene and the antiferromagnetic surface host their own polariton modes coupling the electromagnetic field with plasmons in the case of graphene, and with magnons in the case of the antiferromagnet. We show that the hybrid structure can host two new types of hybrid polariton modes. First, a surface magnon-plasmon polariton whose dispersion is radically changed by the carrier density of the graphene layer, including a change of sign in the group velocity. Second, a surface plasmon-magnon polariton formed as a linear superposition of graphene surface plasmon and the antiferromagnetic bare magnon. This polariton has a dispersion with two branches, formed by the anticrossing between the dispersive surface plasmon and the magnon. We discuss the potential these new modes have for combining photons, magnons, and plasmons to reach new functionalities.
Y V Bludov; Jose N Gomes; Gil De Aquino Farias; Joaquín Fernández-Rossier; Mikhail I Vasilevskiy; N M R Peres. Hybrid plasmon-magnon polaritons in graphene-antiferromagnet heterostructures. 2D Materials 2019, 6, 045003 .
AMA StyleY V Bludov, Jose N Gomes, Gil De Aquino Farias, Joaquín Fernández-Rossier, Mikhail I Vasilevskiy, N M R Peres. Hybrid plasmon-magnon polaritons in graphene-antiferromagnet heterostructures. 2D Materials. 2019; 6 (4):045003.
Chicago/Turabian StyleY V Bludov; Jose N Gomes; Gil De Aquino Farias; Joaquín Fernández-Rossier; Mikhail I Vasilevskiy; N M R Peres. 2019. "Hybrid plasmon-magnon polaritons in graphene-antiferromagnet heterostructures." 2D Materials 6, no. 4: 045003.
Tamm polaritons (TPs) are formed at the interface between two semi-infinite periodic dielectric structures (Bragg mirrors) or other reflectors. Contrary to usual surface polaritons, TPs exist inside the "light cone", even though their amplitude also decreases exponentially with the distance from the interface as it is characteristic of evanescent waves. They couple to elementary excitations in the materials or structures that form the interface, such as metal plasmons or semiconductor excitons. Here we discuss the formation of TPs in the far-infrared (FIR) spectral range, in the optical-phonon reststrahlen band of a polar semiconductor such as GaAs, with a Bragg reflector (BR) as the second mirror. Their dispersion relation and the frequency window for the TP existence are discussed for a GaAs-BR interface. Structures containing a gap between the two reflectors are also considered. Further investigation is performed on a structure containing a layer of graphene between the two reflectors.
Jorge M. S. S. Silva; Mikhail I. Vasilevskiy. Far-infrared Tamm polaritons in a microcavity with incorporated graphene sheet. 2019, 1 .
AMA StyleJorge M. S. S. Silva, Mikhail I. Vasilevskiy. Far-infrared Tamm polaritons in a microcavity with incorporated graphene sheet. . 2019; ():1.
Chicago/Turabian StyleJorge M. S. S. Silva; Mikhail I. Vasilevskiy. 2019. "Far-infrared Tamm polaritons in a microcavity with incorporated graphene sheet." , no. : 1.
Rui M. S. Pereira; Joel Borges; Georgui V. Smirnov; Filipe Vaz; Mikhail I. Vasilevskiy. Surface Plasmon Resonance in a metallic nanoparticle embedded in a semiconductor matrix: exciton-plasmon coupling. 2018, 1 .
AMA StyleRui M. S. Pereira, Joel Borges, Georgui V. Smirnov, Filipe Vaz, Mikhail I. Vasilevskiy. Surface Plasmon Resonance in a metallic nanoparticle embedded in a semiconductor matrix: exciton-plasmon coupling. . 2018; ():1.
Chicago/Turabian StyleRui M. S. Pereira; Joel Borges; Georgui V. Smirnov; Filipe Vaz; Mikhail I. Vasilevskiy. 2018. "Surface Plasmon Resonance in a metallic nanoparticle embedded in a semiconductor matrix: exciton-plasmon coupling." , no. : 1.
The effects of the composition and macroscopic strain on the structural properties and lattice vibrations of SnxGe1-x solid solutions (SSs) are investigated numerically, employing Tersoff empirical inter-atomic potentials, and experimentally. The calculations provide statistical distributions of bond lengths, pair correlation function, and vibrational Raman spectra of the SSs. Using this approach, we are able to evaluate the tin-content-dependent shifts due to the local environment (i.e., changes in the atomic mass and bond stiffness) and strain effects in the calculated Raman spectra and compare them to experimental data. The relative importance of the composition dependent effects of the local environment and strain for epitaxial layers of GeSn solid solutions is analysed.
A. S. Vasin; F. Oliveira; M. F. Cerqueira; J. Schulze; M. I. Vasilevskiy. Structural and vibrational properties of SnxGe1-x: Modeling and experiments. Journal of Applied Physics 2018, 124, 035105 .
AMA StyleA. S. Vasin, F. Oliveira, M. F. Cerqueira, J. Schulze, M. I. Vasilevskiy. Structural and vibrational properties of SnxGe1-x: Modeling and experiments. Journal of Applied Physics. 2018; 124 (3):035105.
Chicago/Turabian StyleA. S. Vasin; F. Oliveira; M. F. Cerqueira; J. Schulze; M. I. Vasilevskiy. 2018. "Structural and vibrational properties of SnxGe1-x: Modeling and experiments." Journal of Applied Physics 124, no. 3: 035105.
We discuss the renormalization of the polarizability of a nanoparticle in the presence of either: (1) a continuous graphene sheet; or (2) a plasmonic graphene grating, taking into account retardation effects. Our analysis demonstrates that the excitation of surface plasmon polaritons in graphene produces a large enhancement of the real and imaginary parts of the renormalized polarizability. We show that the imaginary part can be changed by a factor of up to 100 relative to its value in the absence of graphene. We also show that the resonance in the case of the grating is narrower than in the continuous sheet. In the case of the grating it is shown that the resonance can be tuned by changing the grating geometric parameters.
B. Amorim; P. A. D. Gonçalves; M. I. Vasilevskiy; N. M. R. Peres. Impact of Graphene on the Polarizability of a Neighbour Nanoparticle: A Dyadic Green’s Function Study. Applied Sciences 2017, 7, 1158 .
AMA StyleB. Amorim, P. A. D. Gonçalves, M. I. Vasilevskiy, N. M. R. Peres. Impact of Graphene on the Polarizability of a Neighbour Nanoparticle: A Dyadic Green’s Function Study. Applied Sciences. 2017; 7 (11):1158.
Chicago/Turabian StyleB. Amorim; P. A. D. Gonçalves; M. I. Vasilevskiy; N. M. R. Peres. 2017. "Impact of Graphene on the Polarizability of a Neighbour Nanoparticle: A Dyadic Green’s Function Study." Applied Sciences 7, no. 11: 1158.
André Souto; Rui M. S. Pereira; Jaime Santos; Nuno Peres; Mikhail Vasilevskiy. Electromagnetic properties of a monolayer of polarisable particles deposited on graphene. Third International Conference on Applications of Optics and Photonics 2017, 1 .
AMA StyleAndré Souto, Rui M. S. Pereira, Jaime Santos, Nuno Peres, Mikhail Vasilevskiy. Electromagnetic properties of a monolayer of polarisable particles deposited on graphene. Third International Conference on Applications of Optics and Photonics. 2017; ():1.
Chicago/Turabian StyleAndré Souto; Rui M. S. Pereira; Jaime Santos; Nuno Peres; Mikhail Vasilevskiy. 2017. "Electromagnetic properties of a monolayer of polarisable particles deposited on graphene." Third International Conference on Applications of Optics and Photonics , no. : 1.
This work, motivated by the technologically important task of determination of carbon dopant location in the GaN crystal lattice, employed Raman spectroscopy, with both resonant and non-resonant excitation, and infrared (IR) spectroscopy, in the attenuated total reflection (ATR) configuration, to study lattice vibration modes in a set of carbon-doped GaN (GaN:C) epilayers grown by metalorganic vapour phase epitaxy. We analyse Raman and IR-ATR spectra from the point of view of possible effects of the carbon doping, namely: (i) local vibration mode of C atoms in the nitrogen sublattice (whose frequency we theoretically estimate as 768 cm−1 using an isotope defect model), and (ii) shift in the positions of longitudinal modes owing to the phonon–plasmon coupling. We find only indirect hints of the doping effect on the resonant Raman spectra. However, we show theoretically and confirm experimentally that the IR-ATR spectroscopy can be a much more sensitive tool for this purpose, at least for the considered structures. A weak perturbation of the dielectric function of GaN:C, caused by the substitutional carbon impurity, is shown to produce a measurable dip in the ATR reflectivity spectra at ≈770 cm−1 for both p- and s-polarizations. Moreover, it influences a specific (guided-wave type) mode observed at ≈737 cm−1, originating from the GaN layer, which appears in the narrow frequency window where the real parts of the two components of the dielectric tensor of the hexagonal crystal have opposite signs. This interpretation is supported by our modelling of the whole multilayer structure, using a transfer matrix formalism.
M. Fatima Cerqueira; Luís Vieira; A Alves; Maria Rosário Correia; M Huber; A Andreev; Alberta Bonanni; Mikhail Vasilevskiy. Raman and IR-ATR spectroscopy studies of heteroepitaxial structures with a GaN:C top layer. Journal of Physics D: Applied Physics 2017, 50, 365103 .
AMA StyleM. Fatima Cerqueira, Luís Vieira, A Alves, Maria Rosário Correia, M Huber, A Andreev, Alberta Bonanni, Mikhail Vasilevskiy. Raman and IR-ATR spectroscopy studies of heteroepitaxial structures with a GaN:C top layer. Journal of Physics D: Applied Physics. 2017; 50 (36):365103.
Chicago/Turabian StyleM. Fatima Cerqueira; Luís Vieira; A Alves; Maria Rosário Correia; M Huber; A Andreev; Alberta Bonanni; Mikhail Vasilevskiy. 2017. "Raman and IR-ATR spectroscopy studies of heteroepitaxial structures with a GaN:C top layer." Journal of Physics D: Applied Physics 50, no. 36: 365103.
The ability to effectively guide electromagnetic radiation below the diffraction limit is of the utmost importance in the prospect of all-optical plasmonic circuitry. Here, we propose an alternative solution to conventional metal-based plasmonics by exploiting the deep subwavelength confinement and tunability of graphene plasmons guided along the apex of a graphene-covered dielectric wedge or groove. In particular, we present a quasi-analytic model to describe the plasmonic eigenmodes in such a system, including the complete determination of their spectrum and corresponding induced potential and electric-field distributions. We have found that the dispersion of wedge/groove graphene plasmons follows the same functional dependence as their flat-graphene plasmon counterparts, but now scaled by a (purely) geometric factor in which all the information about the system’s geometry is contained. We believe our results pave the way for the development of novel custom-tailored photonic devices for subwavelength waveguiding and localization of light based on recently discovered 2D materials.
P. A. D. Gonçalves; E. J. C. Dias; Sanshui Xiao; M. I. Vasilevskiy; N. Asger Mortensen; N. M. R. Peres. Graphene Plasmons in Triangular Wedges and Grooves. ACS Photonics 2016, 3, 2176 -2183.
AMA StyleP. A. D. Gonçalves, E. J. C. Dias, Sanshui Xiao, M. I. Vasilevskiy, N. Asger Mortensen, N. M. R. Peres. Graphene Plasmons in Triangular Wedges and Grooves. ACS Photonics. 2016; 3 (11):2176-2183.
Chicago/Turabian StyleP. A. D. Gonçalves; E. J. C. Dias; Sanshui Xiao; M. I. Vasilevskiy; N. Asger Mortensen; N. M. R. Peres. 2016. "Graphene Plasmons in Triangular Wedges and Grooves." ACS Photonics 3, no. 11: 2176-2183.
J. Borges; Marco S. Rodrigues; Cláudia Lopes; Manuel Costa; Armando Ferreira; Rui M. S. Pereira; Mikhail Vasilevskiy; Filipe Vaz. Back Cover: Ag fractals formed on top of a porous TiO 2 thin film (Phys. Status Solidi RRL 7/2016). physica status solidi (RRL) – Rapid Research Letters 2016, 10, 1 .
AMA StyleJ. Borges, Marco S. Rodrigues, Cláudia Lopes, Manuel Costa, Armando Ferreira, Rui M. S. Pereira, Mikhail Vasilevskiy, Filipe Vaz. Back Cover: Ag fractals formed on top of a porous TiO 2 thin film (Phys. Status Solidi RRL 7/2016). physica status solidi (RRL) – Rapid Research Letters. 2016; 10 (7):1.
Chicago/Turabian StyleJ. Borges; Marco S. Rodrigues; Cláudia Lopes; Manuel Costa; Armando Ferreira; Rui M. S. Pereira; Mikhail Vasilevskiy; Filipe Vaz. 2016. "Back Cover: Ag fractals formed on top of a porous TiO 2 thin film (Phys. Status Solidi RRL 7/2016)." physica status solidi (RRL) – Rapid Research Letters 10, no. 7: 1.
The effect of Au nanoparticles (NPs) concentration, size and spatial distribution within a TiO2 dielectric matrix on the Localized Surface Plasmon Resonance (LSPR) band characteristics, were experimentally and theoretically studied. The results of the analysis of the Au NPs’ size distributions allowed to conclude that isolated NPs grow only up to 5-6 nm in size, even for the highest annealing temperature used. However, for higher volume fractions of Au, the coalescence of closely located NPs yields elongated clusters, which are much larger in size and cause a considerable broadening of the LSPR band. This effect was confirmed by Monte Carlo modeling results. Coupled dipole equations were solved to find the electromagnetic modes of a supercell, where isolated and coalesced NPs were distributed, from which an effective dielectric function of the nanocomposite material was calculated and used to evaluate the optical transmittance and reflectance spectra. The modeling results suggested that the observed LSPR band broadening is due to a wider spectral distribution of plasmonic modes, caused by the presence of coalesced NPs (in addition to the usual damping effect). This is particularly important for detection applications via Surface-Enhanced Raman Spectroscopy (SERS), where it is desirable to have a spectrally broad LSPR band in order to favor the fulfillment of the conditions of resonant matching, to electronic transitions in detected species.
Joel Borges; Rui Miguel M. S. Pereira; Marco Sampaio S. Rodrigues; Tomas Kubart; S. Kumar; Klaus Leifer; Albano Cavaleiro; Tomaš Polcar; Mikhail I. Vasilevskiy; Filipe Vaz. Broadband Optical Absorption Caused by the Plasmonic Response of Coalesced Au Nanoparticles Embedded in a TiO2 Matrix. The Journal of Physical Chemistry C 2016, 120, 16931 -16945.
AMA StyleJoel Borges, Rui Miguel M. S. Pereira, Marco Sampaio S. Rodrigues, Tomas Kubart, S. Kumar, Klaus Leifer, Albano Cavaleiro, Tomaš Polcar, Mikhail I. Vasilevskiy, Filipe Vaz. Broadband Optical Absorption Caused by the Plasmonic Response of Coalesced Au Nanoparticles Embedded in a TiO2 Matrix. The Journal of Physical Chemistry C. 2016; 120 (30):16931-16945.
Chicago/Turabian StyleJoel Borges; Rui Miguel M. S. Pereira; Marco Sampaio S. Rodrigues; Tomas Kubart; S. Kumar; Klaus Leifer; Albano Cavaleiro; Tomaš Polcar; Mikhail I. Vasilevskiy; Filipe Vaz. 2016. "Broadband Optical Absorption Caused by the Plasmonic Response of Coalesced Au Nanoparticles Embedded in a TiO2 Matrix." The Journal of Physical Chemistry C 120, no. 30: 16931-16945.
Several potentially interesting plasmonic effects can arise from combining graphene with polarisable nanoparticles (NPs), such as metallic or dielectric spheres, related to surface plasmon-polaritons (SPPs) supported by the latter in the terahertz (THz) spectral range. Owing to the electromagnetic coupling between the graphene SPPs and dipole moments of polarisable (nano-) particles deposited on top of it, the optical properties of such a composite system have some new features as compared to its constituents. First, the NP's polarizability is renormalized due to the electromagnetic back action of SPPs which are excited in graphene when an external propagating electromagnetic wave impinges on the particle. The coupling also results in a considerable enhancement of the THz radiation absorption in graphene, while the reflection drops to zero. This effect can be potentially interesting e.g. for cloaking in a certain THz frequency range.
Mikhail Vasilevskiy; Jaime Eduardo Vieira Da Silva Moutinho Santos; Rui M. S. Pereira; Yuliy Bludov; Filipe Vaz; N. M. R. Peres. Graphene and polarisable nanoparticles: Looking good together? 2016 18th International Conference on Transparent Optical Networks (ICTON) 2016, 1 -4.
AMA StyleMikhail Vasilevskiy, Jaime Eduardo Vieira Da Silva Moutinho Santos, Rui M. S. Pereira, Yuliy Bludov, Filipe Vaz, N. M. R. Peres. Graphene and polarisable nanoparticles: Looking good together? 2016 18th International Conference on Transparent Optical Networks (ICTON). 2016; ():1-4.
Chicago/Turabian StyleMikhail Vasilevskiy; Jaime Eduardo Vieira Da Silva Moutinho Santos; Rui M. S. Pereira; Yuliy Bludov; Filipe Vaz; N. M. R. Peres. 2016. "Graphene and polarisable nanoparticles: Looking good together?" 2016 18th International Conference on Transparent Optical Networks (ICTON) , no. : 1-4.
The propagation of a surface plasmon polariton along a stack of doped graphene sheets is considered. This auxiliary problem is used to discuss: (i) the scattering of such a mode at an interface between the stack and the vacuum, and (ii) the scattering at an interface where there is a sudden change of the electronic doping. The formalism is then extended to the barrier problem. In this system rich physics is found for the plasmonic mode, showing total reflection, total transmission, Fabry-Pérot oscillations, and coupling to photonic modes.
Yuliy Bludov; N. M. R. Peres; Georgi Smirnov; Mikhail Vasilevskiy. Scattering of surface plasmon polaritons in a graphene multilayer photonic crystal with inhomogeneous doping. Physical Review B 2016, 93, 245425 .
AMA StyleYuliy Bludov, N. M. R. Peres, Georgi Smirnov, Mikhail Vasilevskiy. Scattering of surface plasmon polaritons in a graphene multilayer photonic crystal with inhomogeneous doping. Physical Review B. 2016; 93 (24):245425.
Chicago/Turabian StyleYuliy Bludov; N. M. R. Peres; Georgi Smirnov; Mikhail Vasilevskiy. 2016. "Scattering of surface plasmon polaritons in a graphene multilayer photonic crystal with inhomogeneous doping." Physical Review B 93, no. 24: 245425.
Joel Borges; Marco S. Rodrigues; Cláudia Lopes; Diogo Costa; Armando Ferreira; Rui M. S. Pereira; Manuel Costa; Mikhail Vasilevskiy; Filipe Vaz. Ag fractals formed on top of a porous TiO2thin film. physica status solidi (RRL) – Rapid Research Letters 2016, 10, 530 -534.
AMA StyleJoel Borges, Marco S. Rodrigues, Cláudia Lopes, Diogo Costa, Armando Ferreira, Rui M. S. Pereira, Manuel Costa, Mikhail Vasilevskiy, Filipe Vaz. Ag fractals formed on top of a porous TiO2thin film. physica status solidi (RRL) – Rapid Research Letters. 2016; 10 (7):530-534.
Chicago/Turabian StyleJoel Borges; Marco S. Rodrigues; Cláudia Lopes; Diogo Costa; Armando Ferreira; Rui M. S. Pereira; Manuel Costa; Mikhail Vasilevskiy; Filipe Vaz. 2016. "Ag fractals formed on top of a porous TiO2thin film." physica status solidi (RRL) – Rapid Research Letters 10, no. 7: 530-534.
We have studied light emission kinetics and analyzed carrier recombination channels in HgTe quantum dots that were initially grown in H2O. When the solvent is replaced by D2O, the nonradiative recombination rate changes highlight the role of the vibrational degrees of freedom in the medium surrounding the dots, including both solvent and ligands. The contributing energy loss mechanisms have been evaluated by developing quantitative models for the nonradiative recombination via (i) polaron states formed by strong coupling of ligand vibration modes to a surface trap state (nonresonant channel) and (ii) resonant energy transfer to vibration modes in the solvent. We conclude that channel (i) is more important than (ii) for HgTe dots in either solution. When some of these modes are removed from the relevant spectral range by the H2O to D2O replacement, the polaron effect becomes weaker and the nonradiative lifetime increases. Comparisons with CdTe quantum dots (QDs) served as a reference where the resonant energy loss (ii) a priori was not a factor, also confirmed by our experiments. The solvent exchange (H2O to D2O), however, is found to slightly increase the overall quantum yield of CdTe samples, probably by increasing the fraction of bright dots in the ensemble. The fundamental study reported here can serve as the foundation for the design and optimization principles of narrow bandgap quantum dots aimed at applications in long wavelength colloidal materials for infrared light emitting diodes and photodetectors.
Qiannan Wen; Stephen V. Kershaw; Sergii Kalytchuk; Olga Zhovtiuk; Claas J. Reckmeier; Mikhail I. Vasilevskiy; Andrey L. Rogach. Impact of D2O/H2O Solvent Exchange on the Emission of HgTe and CdTe Quantum Dots: Polaron and Energy Transfer Effects. ACS Nano 2016, 10, 4301 -4311.
AMA StyleQiannan Wen, Stephen V. Kershaw, Sergii Kalytchuk, Olga Zhovtiuk, Claas J. Reckmeier, Mikhail I. Vasilevskiy, Andrey L. Rogach. Impact of D2O/H2O Solvent Exchange on the Emission of HgTe and CdTe Quantum Dots: Polaron and Energy Transfer Effects. ACS Nano. 2016; 10 (4):4301-4311.
Chicago/Turabian StyleQiannan Wen; Stephen V. Kershaw; Sergii Kalytchuk; Olga Zhovtiuk; Claas J. Reckmeier; Mikhail I. Vasilevskiy; Andrey L. Rogach. 2016. "Impact of D2O/H2O Solvent Exchange on the Emission of HgTe and CdTe Quantum Dots: Polaron and Energy Transfer Effects." ACS Nano 10, no. 4: 4301-4311.