Juana Gervasoni - Academia.edu (original) (raw)

Papers by Juana Gervasoni

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2009

We give a short overview of the dispersion relation for plasmon excitations in nanosystems of sph... more We give a short overview of the dispersion relation for plasmon excitations in nanosystems of spherical (spheres, cavities and concentric spherical shells) and cylindrical (capillaries, wires and tubes) symmetries. We describe the interaction of external charged particles with the nanomaterials by using the dielectric response function. We apply the calculation to the case of electrons impacting nanosurfaces of Aluminum. We show how different is the response of the surface depending of its shape and configuration.

International Journal of Hydrogen Energy, 2008

Graphene Science Handbook, 2016

This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN Hot-carrier optoelectronic ... more This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN Hot-carrier optoelectronic devices based on semiconductor nanowires Applied Physics Reviews 8, 021309 (2021);

En las últimas décadas, Argentina ha avanzado significativamente encuestiones de género mediante ... more En las últimas décadas, Argentina ha avanzado significativamente encuestiones de género mediante la sanción de leyes y la incorporaciónde regulaciones internacionales a su marco normativo. La proporciónde mujeres que estudian y finalizan carreras universitarias ha crecidonotablemente al punto de que, en las mayores universidades del país, elnúmero total de estudiantes y de egresadas mujeres supera al de hombres.Algo análogo ha sucedido en distintos organismos vinculados a lainvestigación científica como el Consejo nacional de InvestigacionesCientíficas y Técnicas (Conicet). A pesar de estos avances, la violenciade género sigue siendo prevalente en la sociedad, lo que se refleja enla alta tasa de crímenes de género que aún ocurren contra mujeres. Porotro lado, si bien el número de mujeres universitarias y científicas haaumentado, hay gran diversidad dependiendo de las carreras, e inclusoen aquellas donde las mujeres son mayoría, los grupos de investigaciónsuelen ser liderados por hom...

Physical Review B, 2022

We explore the conservation of energy and momentum by solving Maxwell's equations for a charged p... more We explore the conservation of energy and momentum by solving Maxwell's equations for a charged particle passing through a single conductive sheet. By using a fully relativistic formulation of the problem, we evaluate the energy and momentum transfer from charged particle to electronic excitations localized in the sheet and to electromagnetic radiation emitted from the sheet in the far-field region. Using a suitable conductivity model for the sheet that can represent graphene or other two-dimensional (2D) material, our theory can elucidate the energy and momentum transfer involving the incident particle, plasmon polariton mode(s) in the 2D material, and the induced transition radiation from it.

Journal of Applied Physics, 2021

We assess the applicability of the oscillator model to evaluate the energy loss of a fast charged... more We assess the applicability of the oscillator model to evaluate the energy loss of a fast charged particle incident on graphene. We study the cases of a parallel and perpendicular trajectory of the particle. We focus on two frequency regimes for graphene's electron response: the optical regime, which is dominated by two types of oscillators with non-dispersing frequencies in the ultraviolet regime, and the terahertz (THz) regime, which is dominated by a strongly dispersing sheet plasmon mode in doped graphene. In the latter regime, we invoke the kinematic resonance condition for a parallel trajectory, and we propose a method for averaging the energy loss for a perpendicular trajectory. We show that the oscillator model provides analytical expressions, which give results in generally good agreement with a dielectric-response approach to the same problem, even in the THz regime.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2021

Abstract In this work we present a fully relativistic formulation for the energy loss of an exter... more Abstract In this work we present a fully relativistic formulation for the energy loss of an external charged particle interacting with a 2D material. We model this material as a monolayer of atoms represented by harmonic oscillators, with isotropic or anisotropic electronic vibration modes. We develop the model for a wide range of incident energies and considering both parallel and perpendicular trajectories.

Journal of Energy and Power Engineering, 2018

The analysis of the interaction of hydrogen, nitrogen (and their isotopes) with tungsten is impor... more The analysis of the interaction of hydrogen, nitrogen (and their isotopes) with tungsten is important, since this material is a strong candidate to form the first wall of fusion reactors for both magnetic and inertial confinement, and these atoms have a very sensitive (desired and unwanted) interaction with it. For this purpose, we study the effects and electronic state densities of atomic hydrogen and nitrogen in pure tungsten, in order to analyze some important properties such as the density of states of the system. Focusing on this application, this work is a preliminary study of the behavior of atoms of hydrogen and nitrogen, on a surface of tungsten on the three sites of the cell: top, hollow and bridge. We use a program simulation based on the DFT (density functional theory) implemented in the Open-Source Code Quantum Espresso, in order to obtain the adsorption energy and the density of states of the systems.

Radiation Physics and Chemistry, 2007

In this work we study the excitation of surface plasmons in tubular nanostructures by impact of c... more In this work we study the excitation of surface plasmons in tubular nanostructures by impact of charged particles. The dispersion relation for the frequencies of the modes is studied on the basis of a Drude model for the dielectric function, and the results are compared to the cases of capillaries and wires. This approach is used to calculate the induced field and the stopping force on a particle following a trajectory parallel to the tube axis.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2017

We address the problem of quantifying the decay of plasmons excited in the electron gas of a cond... more We address the problem of quantifying the decay of plasmons excited in the electron gas of a condensed medium. Within the dielectric formalism, we thoroughly describe the theoretical framework in which we define the damping parameter c. We present two detailed procedures to assess it as a function of the momentum transfer q, one based on a classical description of the excitation process and the second based on a quantum formulation of it. We present results corresponding to aluminum and magnesium, and compare them with experimental data obtained from the literature.

Surface Science, 1992

We study the interaction with bulk and surface modes of electrons emitted in the proximity of a s... more We study the interaction with bulk and surface modes of electrons emitted in the proximity of a solid surface. We analyze the mod~ications in the energy loss, and in bulk and surface plasmon excitations, taking into account the effects due to the sudden creation of the electron and residual atomic hole, and the finite distance to the surface. The process is described using the dielectric function formulation and the specular reflection model. We derive expressions for the electrostatic potential in the medium and in vacuum, which include all the terms due to bulk and surface modes. The effect of each term in the energy loss rate and in the average number of piasmon excitations is discussed. The results illustrate in detail the different spatial dependences of the electron and ion interactions with the bulk and surface perturbations, through the relevant range of distances for studies of electron emission in the proximity of solid surfaces.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015

We study the fluctuations of the plasmon field associated to the wake potential generated by a di... more We study the fluctuations of the plasmon field associated to the wake potential generated by a dimer formed by two identical charged particles (such as two nuclei of the ionized hydrogen molecule) traveling through a semiinfinite dielectric medium. We use coherent states to describe bulk and surface plasmons as wave packets that raise fluctuations in the electronic density of the material. We analyze different configurations of interest, taking into account various trajectories and orientations of the dimer.

Journal of Materials Science, 1998

In the present work a semiempirical method for characterizing the electronic density of pure meta... more In the present work a semiempirical method for characterizing the electronic density of pure metals (or, equivalently, the mean radius, rs, per electron) from the bulk modulus is proposed. The general features of this method are discussed and shown to be simple and useful for many situations. Knowledge of rs is important because it determines several important properties of the

Plasmonics, 2015

In this work, we develop a theoretical quantum mechanical model for describing the plasmon excita... more In this work, we develop a theoretical quantum mechanical model for describing the plasmon excitations in nanostructures. This model is based on the electronic density according to the Density Functional Theory (DFT). We derive an expression for finding an approximation to the dispersion relation in a nanostructure from the complete Hamiltonian of the system. We apply this expression to an aluminium nanoring showing how great, and not negligible, the ionic-interaction term is.

Physical Review B, 2003

We study the interaction of external charged particles with the bulk and surface modes of cylindr... more We study the interaction of external charged particles with the bulk and surface modes of cylindrical wires using classical and quantum mechanical formulations. First, the dielectric function approach is used to calculate the main induced effects and to derive the average number of excited plasmons in a semiclassical way. Second, the surface and bulk plasmon fields are quantized and the corresponding processes of plasmon excitations are described in detail. The correspondence between the classical and quantum pictures is shown. General scaling properties of the interaction terms are presented, and various illustrative examples are given.

Vacuum, 2014

In this work we study the surface plasmon generation by a suddenly created electron-hole pair in ... more In this work we study the surface plasmon generation by a suddenly created electron-hole pair in nanoparticles of spherical shape. We use a previously developed model based on the Hamiltonian formulation for plasmon field.

Vacuum, 2009

In this work we investigate in detail the effects due to the interaction between an electron and ... more In this work we investigate in detail the effects due to the interaction between an electron and a stationary positive ion (or atomic hole) in the neighbourhood of a nanostructured surface. In particular, we study how a positive charge, located near to the surface of a nanostructured (cylindrically shaped) body, can influence the probability of the surface plasmon excitations and consequently the energy loss of the emerging electron. We deal with simple nanostructured systems of Al, having a strong plasmon peak in its electron energy loss spectra. The method described here is useful for understanding the electron spectra excited from these nanostructures (different from those of the same bulk material).