Ponencias (Física Aplicada I)
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Ponencia A semiclassical model for charge transfer along ion chains in silicates(IOP Publishing, 2024) Archilla, Juan F. R.; Bajārs, Jānis; Doi, Yusuke; Kimura, Masayuki; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; University of Latvia; Universidad de Sevilla. FQM280: Física no LinealIt has been observed in fossil tracks and experiments in the layered silicate mica muscovite the transport of charge through the cation layers sandwiched between the layers of tetrahedra-octahedra-tetrahedra. A classical model for the propagation of anharmonic vibrations along the cation chains has been proposed based on first principles and empirical functions. In that model, several propagating entities have been found as kinks or crowdions and breathers, both with or without wings, the latter for specific velocities and energies. Crowdions are equivalent to moving interstitials and transport electric charge if the moving particle is an ion, but they also imply the movement of mass, which was not observed in the experiments. Breathers, being just vibrational entities, do not transport charge. In this work, we present a semiclassical model obtained by adding a quantum particle, electron or hole to the previous model. We present the construction of the model based on the physics of the system. In particular, the strongly nonlinear vibronic interaction between the nuclei and the extra electron or hole is essential to explain the localized charge transport, which is not compatible with the adiabatic approximation. The formation of vibrational localized charge carriers breaks the lattice symmetry group in a similar fashion to the Jahn-Teller Effect, providing a new stable dynamical state. We study the properties and the coherence of the model through numerical simulations from initial conditions obtained by tail analysis and other means. We observe that although the charge spreads from an initial localization in a lattice at equilibrium, it can be confined basically to a single particle when coupled to a chaotic quasiperiodic breather. This is coherent with the observation that experiments imply that a population of charge is formed due to the decay of potassium unstable isotopes.Ponencia Quodons in tokamak fusion reactors(IEICE Digital Library, 2023) Russell, F. Michael; Archilla, Juan F. R.; Universidad de Sevilla. Departamento de Física Aplicada IExperiments have shown that alpha particles incident on different materials bring about the generation of quodons, that is packets of localized energy that can bind to an electric charge and transport it without the presence of an electric field, a phenomenon called hyperconductivity. Tokamak fusion reactors produce a huge amount of alpha particles, transporting energy and charge trough insulators and metals at much more speed that ohmic conduction and heat conductivity. The consequences are still unclear but should be studied and incorporated in reactor designs.Ponencia Spectrum of polarobreathers in a model for layered silicates(IEICE Digital Library, 2023) Archilla, Juan F. R.; Bajars, Janis; Doi, Yusuke; Kimura, Masayuki; Universidad de Sevilla. Departamento de Física Aplicada IExperiments in layered silicated have shown the capability of nonlinear excitations to couple with electric charge and transport it without the presence of an electric field, a phenomenon called hyperconductivity. We have constructed a model for these excitations and using the theory of exact breathers in their moving frame, obtained breathers coupled to a charge that travel carried by a nonlinear localized wave.Ponencia Geometric numerical integration of semi-classical Hamiltonain lattice dynamics(IEICE Digital Library, 2022) Bajars, Janis; Archilla, Juan F. R.; Universidad de Sevilla. Departamento de Física Aplicada IIn this work we provide a brief overview of recently proposed symplecticity-preserving symmetric splitting methods for semi-classical Hamiltonian dynamics of charge transfer by intrinsic localized modes in nonlinear crystal lattice models [1]. Without loss of generality, we consider one-dimensional crystal lattice models described by classical Hamiltonian dynamics, whereas charge particle is modeled as quantum particle within the tight-binding approximation. Canonical Hamiltonian equations for the coupled lattice-charge dynamics are derived. Structurepreserving splitting methods are constructed by splitting the total Hamiltonian into the sum of Hamiltonians which individual dynamics can be solved exactly. Exactly charge conserving symplectic splitting methods are also proposed which require only one solution of a linear system of equations per time step. Developed computationally efficient non-dissipative methods provide new means for long-time simulations of charge transfer by nonlinear lattice excitations.Ponencia Supratransmission-induced discrete rogue wave in nonlinear chain(IEICE Digital Library, 2022) Togueu Motcheyo, Alain B.; Kimura, Masayuki; Doi, Yusuke; Archilla, Juan F. R.; Universidad de Sevilla. Departamento de Física Aplicada IWe numerically generate a discrete rogue wave in a chain of a nonlinear pendulum using the nonlinear supratransmission way and the instability of shaken pendulum. This could open the way for the application of discrete rogue waves within simple devices.Ponencia A tight-binding model for charge transport in silicate layers(IEICE Digital Library, 2020) Archilla, Juan F. R.; Doi, Yusuke; Kimura, Masayuki; Universidad de Sevilla. Departamento de Física Aplicada IObservations and experiments in silicates of the mica group show the transport of electric charge along the cation layers in absence of an electric field, a phenomenon called hyperconductivity. The transport of charge is achieved when a nonlinear vibration brings about that the ions become close enough for the transfer of an electron or hole. A model is developed in detail, approximations of different order for smaller vibration are considered so as to obtain approximate solutions. The full equations are integrated numerically with several approaches to overcome the problem caused by the different time scales of ion and electron movements. Localized solution showing the transport of charge coupled to nonlinear excitations are observed and described.Ponencia One-dimensional models for liquid columns subjected to electric fields(IEEE, 1994-10) Castellanos Mata, Antonio; García García, Francisco Javier; González García, Heliodoro; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada III; Dirección General Interministerial de Ciencia y Tecnología (DGICYT). EspañaAn analysis of slender axisymmetric liquid columns is performed on the basis of one-dimensional models, recently derived and generalized here to include the effect of dielectric forces at the interface. The natural frequencies and stability criteria in the absence of gravity are obtained. Results are compared with the known exact linear solutions of the corresponding three-dimensional problems.Ponencia Perpendicular-field EHD instabilities visualized in a tip-plane configuration(IEEE Xplore, 2002-10) Vega, F.; Pérez Izquierdo, Alberto Tomás; García García, Francisco Javier; Castellanos, Antonio; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Ministerio de Ciencia y Tecnología (MCYT). EspañaEHD interfacial instabilities can be induced by corona discharge from a tip electrode onto a liquid-air interface. The corona current charges the liquid surface and instabilities may appear depending on the applied voltage and the liquid properties. We present a technique to detect the onset of instability based on image processing. To establish the instability threshold we apply an edge-detection algorithm to images of the liquid surface acquired through a videa camera.Ponencia Dynamics and deformation of a drop in a DC electric field(IEEE Xplore, 2003-10) Khayari, Abdelmounim; Pérez Izquierdo, Alberto Tomás; García García, Francisco Javier; Castellanos, Antonio; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Ministerio de Ciencia Y Tecnología (MCYT). EspañaWe consider a single conducting drop in suspension in a poorly conducting liquid between two horizontal electrodes. When a DC field is applied to the electrodes, the drop charges and rises within the'liquid, then falls down as its charge leaks away, due to the finite elechic relaxation time of the liquid. The drop keepsbouncing as long as the high voltage applied remains above a minimum threshold. We focus our study on the dynamics and the deformation of a water drop before the lift-off and during its motion. Electrodes of different materials are used in order to illustrate the role of interfacial energy between the electrode and the water.Artículo The design of an electrostatic variable energy positron beam for studies of defects in ceramic coatings and polymer films(ScienceDirect, 2002-06-22) Abadjieva, E.; Schut, Henk; Alba García, A.; Escobar-Galindo, Ramón; Veen, A. van; Pimblott, S.M.; Universidad de Sevilla. Departamento de Física Aplicada IAn electrostatic variable energy positron beam for studying defects in ceramic coatings, polymer films and MOS-devices is developed for operation in Doppler-broadening (DB) and positron annihilation lifetime (PAL) modes. In DB mode the implantation energy can be varied between 3 and 30 keV with a beam diameter on the target ranging from 0.4 to 0.5 mm FWHM. In PAL mode the start-signal is given by secondary electron emission from a 25 nm thin carbon foil placed in front of the target. After passing the foil the positron beam is focused on the target with a spot size of 2 mm FWHM at 1 keV down to 0.6 mm FWHM at 30 keV. The target chamber is equipped with an in situ four-point bending device for studying defects introduced by tensile and compressive stresses.Artículo Systematic positron study of hydrophilicity of the internal pore surface in ordered low-k silica thin films(ScienceDirect, 2003-09-15) Escobar-Galindo, Ramón; Veen, A. van; Schut, Henk; Eijt, S.W.H.; Falub, Claudiu V.; Balkenende, A.R.; Theije, Fremke de; Universidad de Sevilla. Departamento de Física Aplicada INon-destructive Doppler Broadening (DB), Positronium fraction (f-Ps) and Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR), Positron Beam Analysis (PBA) techniques have been used to study well-ordered mesoporous silica thin films with hydrophobic or hydrophilic character. The DB results, characterized by the S and W parameters, are related to both the open volume and the chemical environment at the positron annihilation site. The f-Ps and 2D-ACAR techniques are very sensitive probes to determine the type of porosity (open or closed in terms of positronium escape) in thin film materials. Samples with varying pore size (well-controlled at 2, 3 and 4.5 nm, or incorporating microporosity in the silica), pore fraction (from 4 to 57%) and extent of hydrophilicity have been studied. In the hydrophilic samples with small pore size the S-parameter increases with the porosity while the Ps-fraction remains almost unchanged. Increasing the pore size leads to smaller changes in S with increasing porosity. However, an abrupt change in the Ps-fraction is observed for samples with porosity higher than 45%, indicating a positronium percolation threshold for samples with 2D ordering structure. On the other hand, for hydrophobic samples with high porosity (57%) the highest S parameter and Ps-fraction were obtained for the three pore sizes studied. 2D-ACAR is used to determine the fraction and velocity of Ps escaping from some of the latter samples exhibiting positronium percolation. The relationship between these observations and porosity will be discussed in terms of branching of the positron annihilation channels inside the mesoporous films.Artículo Thermally induced delamination of amorphous hydrogenated carbon coatings monitored by positron beam analysis(ScienceDirect, 2004-03) Escobar-Galindo, Ramón; Veen, A. van; Schut, Henk; Rabbani, F.; Janssen, G.C.A.M.; Hosson, J.Th.M. de; Universidad de Sevilla. Departamento de Física Aplicada IIn this work we have studied the adhesion of PVD amorphous hydrogenated carbon (a-C:H) thin coatings (<200 nm) on crystalline silicon by means of positron beam analysis (PBA). PBA allows the study of the a-C:H layer and the interface by monitoring changes on the Doppler broadening parameters S and W. Depending on the deposition condition, using PBA some samples were found to be delaminated after deposition. Annealing experiments were performed on samples that did not show signs of delamination after deposition. Some of these samples were distinguished by the fact that nitrogen was used in the manufacturing process. Samples were annealed for 30 min in vacuum up to 600 °C in order to remove gases absorbed at the interface. PBA experiments were performed after each annealing step. For the sample without N2 there are no S–W changes either in the coating or at the interface until 600 °C is reached. On the other hand, for the sample containing N2, there is a gradual change in these parameters with temperature. In this coating, after annealing to 500 °C, the increase in W is related to release of H2 and consequent restructuring of the layer. The decrease in the value of S between 500 and 600 °C indicates the formation of graphitic crystallites. There is open volume at the coating/substrate interface since the S parameter gradually increases while W remains constant until 400 °C. This behaviour in S–W is related to the removal of physisorbed hydrogen. At approximately 400 °C the H bonded to C at tetrahedral sites is also released which leads to an internal restructuring of the ‘lattice’, hence a decrease in the value of S is observed. Finally, at 600 °C both coatings delaminate, as the interface parameters tend towards the same values as those of the sample which had delaminated after deposition.Ponencia Comprehensive environmental testing of optical properties in thin films(ScienceDirect, 2014) Heras, Irene; Guillén Guillén, Elena; Krause, Matthias; Wenisch, Robert; Escobar-Galindo, Ramón; Endrino, José Luis; Universidad de Sevilla. Departamento de Física Aplicada IEnvironmental characterization of optical and structural properties of thin films continues to be a challenging task. To understand the failure mechanism in high temperature thin film applications, it is crucial to understand how material properties change with temperature. An accurate knowledge of the variation of the dielectric function of thin films and its relation to compositional and microstructural changes could help to prevent failures. This article presents an environmental in-situ characterization methodology that combines the study of the optical constants in an environmental chamber by spectroscopic ellipsometry, with compositional depth profile analysis using ion beam analysis techniques and a structure analysis by Raman spectroscopy. The main novelty of this methodology is that all analytical techniques are carried out sequentially in a multi-chamber cluster tool without sample exposure to undefined atmospheres. Carbon-titanium metal thin film had been studied following the described characterization methodologyPonencia Room temperature deposition of highly dense TiO2 thin films by Filtered Cathodic Vacuum Arc(SPIE Digital Library, 2015) Guillén Guillén, Elena; Heras, Irene; Rincón Llorente, G.; Lungwitz, Frank; Alcón Camas, M.; Escobar-Galindo, Ramón; Universidad de Sevilla. Departamento de Física Aplicada I; European Union (UE). H2020A systematic study of TiO2 films deposited by dc filtered cathodic vacuum arc (FCVA) was carried out by varying the deposition parameters in a reactive oxygen atmosphere. The influence of the oxygen partial pressure on film properties is analyzed. Composition was obtained by Rutherford backscattering spectroscopy (RBS) measurements, which also allow us to obtain the density of the films. Morphology of the samples was studied by scanning electron microscopy (SEM) and their optical properties by ellipsometry. Transparent, very dense and stoichiometric TiO2 films were obtained by FCVA at room temperature.Ponencia Vapor and liquid optical monitoring with sculptured Bragg microcavities(SPIE - The International Society for Optical Engineering, 2017) Oliva Ramirez, Manuel; Gil Rostra, Jorge; López Santos, Carmen; Rodríguez González-Elipe, Agustín; Yubero Valencia, Francisco; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Economia, Industria y Competitividad (MINECO). España; Agencia Estatal de Investigación. EspañaSculptured porous Bragg Microcavities (BMs) formed by the successive stacking of columnar SiO2 and TiO2 thin films with zig-zag columnar microstructure are prepared by glancing angle deposition. These BMs act as wavelength dependent optical retarders. This optical behavior is attributed to a self-structuration mechanism involving a fence-bundling association of nanocolumns as observed by Focused Ion Beam Scanning Electron Microscopy. The retardance of these optically active BMs can be modulated by dynamic infiltration of their open porosity with vapors, liquids or solutions with different refractive indices. The tunable birefringence of these nanostructured photonic systems have been successfully simulated with a simple model that assumes that each layer within the BMs stack has uniaxial birefringence. This type of self-associated nanostructures has been incorporated to microfluidic chips for free label vapor and liquid sensing. Several examples of the detection performance of these chips, working either in reflection or transmission configuration, for the optical characterization of vapor and liquids of different refractive index and aqueous solutions of glucose flowing through the microfluidic chips are described.Ponencia A Lagrangian Transport Model Applied to two Different Brackish Systems: the Baltic Sea and the Guadalquivir River(IEEE Computer Society, 2011) Toscano Jiménez, Manuel; Abril Hernández, José María; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. Departamento de Física Aplicada III; Universidad de Sevilla. RNM-138: Física Nuclear Aplicadathe nuclear contamination and other passive particles in the ocean. As a consequence of the Chernobyl accident (April, 26th, 1986), the radioactive plume drift over many countries in Europe, and after some days, the Baltic Sea became the most contaminated ecosystem beyond the Soviet Union. Our Dispersion Model has been validated in this system in order to be useful in other oceanic scenarios affected by radioactive fallout in the future. These investigations could be an interesting tool to predict and minimize the ecological and economical impacts of future accidents and can also be extended to non-nuclear contamination problems such as: oil accidents, chemical contamination, nutrients dynamics and other ecological problems. A new application devoted to the Guadalquivir River has been implemented with the methods used and validated for the Baltic Sea. This transport model is a first step for future applications to passive particles problems such as nutrients, chemical contamination, metals, suspended sediments, etc., or other active parts like salt and fresh water. A deeper knowledge on the Guadalquivir river estuary is being demanding for many socioeconomic and ecological applications in the future.Ponencia Impacto de la docencia asíncrona en el desarrollo de las competencias(Adaya Press; REDINE, 2021) Delgado Sánchez, José María; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. TEP122: Termodinámica y Energías RenovablesLas competencias descritas en los diferentes planes de estudio se consideran una herramienta esencial para la integración profesional y social de los estudiantes en la Sociedad. Cualidades como “trabajo en equipo”, “colaboración” o “adaptación” son cada vez más valoradas por las empresas, superando incluso a veces la especialización técnica del candidato. El presente estudio analiza el impacto que ha tenido en las competencias la adaptación de los planes de estudio a la docencia asíncrona necesaria durante el tiempo de pandemia COVID-19. Se ha comparado como cada competencia se ha visto influenciada por situaciones de aislamiento o interacción social.Ponencia A linear polar molecule in a two-color laser field: a symmetry analysis(IOP Publishing: Conference Series, 2020) Mellado-Alcedo, David; Quintero, Niurka R.; González-Férez, Rosario; Universidad de Sevilla. Departamento de Física Aplicada I; Vernhet, Dominique; Dulieu, Olivier; Universidad de Sevilla. FQM-207 Física Atómica y MolecularWe describe the field-dressed rotational dynamics of a linear polar molecule in a a non-resonant two-color cw laser field, and analyze the orientation and alignment as the field parameters are varied.Ponencia Kinks in Coulomb’s chains(Universidad de Sevilla, 2012) Archilla, Juan F. R.; Kosevich, Yuriy A.; Russell, Mike; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla. FQM280: Física no LinealChains of identical ions, for which the dominant interaction is the electrostatic repulsion, appear in layered silicates. The ions can move almost from site to site. The chains do not explode because the surrounding media has a net negative charge which screens the Coulomb’s repulsion and become attractive when the ions separate two much. Moreover there is a border effect which keeps the ions within the crystal. We have been able to obtain moving supersonic kinks that keep their shape and cross nicely one with each other and can travel over the surrounding sea of phonons. Their energies can be very different, from the order of eVs to hundreds of them. Therefore they can influence many different processes within silicates.Ponencia Atomic Dark-Bright Solitons: Theory and Experiments(2012) Frantzeskakis, Dimitri J.; Kevrekidis, Panayotis G.; Yan, Dong; Carretero-González, Ricardo; Hoefer, Mark A.; Engels, Peter; Chang, J. J.; Hamner, Chris R.; Schmelcher, P.; Middelkamp, S.; Stockhofe, J.; Cuevas-Maraver, Jesús; Álvarez Chillida, María Azucena; Achilleos, Vassos; Rothos, Vassilis M.V; Universidad de Sevilla. Departamento de Física Aplicada I; Universidad de Sevilla .FQM280: Física no Lineal