Hotel Resort Iberostar Quetzal/Tucán Playa del Carmen ... · Este taller es la continuación de...

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Hotel Resort Iberostar Quetzal/Tucán Playa del Carmen, Quintana Roo, México 11 al 14 de diciembre 2016 Comité Organizador Local: Remigio Cabrera-Trujillo, Instituto de Ciencias Físicas, UNAM Salvador A. Cruz, Departamento de Física, UAM-I Rocío Jáuregui, Instituto de Física, UNAM José Ignacio Jiménez Mier y Terán, Instituto de Ciencias Nucleares, UNAM Antonio M. Juárez Reyes, Instituto de Ciencias Físicas, UNAM Ricardo Méndez Fragoso, Facultad de Ciencias, UNAM José Recamier, Instituto de Ciencias Físicas, UNAM Comité científico e internacional: Moni Behar. Instituto de Física, UFRGS, Brasil. Remigio Cabrera-Trujillo, Instituto de Ciencias Físicas, UNAM, México. Pedro L. Grande. Instituto de Física, UFRGS, Brasil. Jorge Miraglia. IAFE-CONICET, Argentina. Roberto Rivarola, IFIR, CONICET-UNR, Argentina. Nelson V. Castro Faría. Instituto de Física, UFRJ, Brasil. Eduardo Montenegro. Instituto de Física, UFRJ, Brasil. Enio F. da Silveira. PUC Río de Janeiro, Brasil. Jorge E. Valdés. UTFSM, Chile.

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  • Hotel Resort Iberostar Quetzal/Tucn

    Playa del Carmen, Quintana Roo, Mxico 11 al 14 de diciembre 2016

    Comit Organizador Local:

    Remigio Cabrera-Trujillo, Instituto de Ciencias Fsicas, UNAM

    Salvador A. Cruz, Departamento de Fsica, UAM-I Roco Juregui, Instituto de Fsica, UNAM

    Jos Ignacio Jimnez Mier y Tern, Instituto de Ciencias Nucleares, UNAM Antonio M. Jurez Reyes, Instituto de Ciencias Fsicas, UNAM

    Ricardo Mndez Fragoso, Facultad de Ciencias, UNAM Jos Recamier, Instituto de Ciencias Fsicas, UNAM

    Comit cientfico e internacional:

    Moni Behar. Instituto de Fsica, UFRGS, Brasil. Remigio Cabrera-Trujillo, Instituto de Ciencias Fsicas, UNAM, Mxico.

    Pedro L. Grande. Instituto de Fsica, UFRGS, Brasil. Jorge Miraglia. IAFE-CONICET, Argentina.

    Roberto Rivarola, IFIR, CONICET-UNR, Argentina. Nelson V. Castro Fara. Instituto de Fsica, UFRJ, Brasil. Eduardo Montenegro. Instituto de Fsica, UFRJ, Brasil.

    Enio F. da Silveira. PUC Ro de Janeiro, Brasil. Jorge E. Valds. UTFSM, Chile.

  • 2

    Prefacio

    Este taller es la continuacin de los primeros siete talleres de colisiones inelsticas en la materia que se llevaron a cabo en Gramado, Brasil en 2002, Via del Mar, Chile en 2004, Buenos Aires, Argentina en 2006, Rio de Janeiro, Brasil en 2008, Valparaso, Chile, en 2010, Rosario, Argentina en 2012 y Gramado, Brasil en 2014 y surge con el objetivo de propiciar la integracin entre los miembros de la comunidad de Fsica Atmica y Molecular, fomentar las colaboraciones entre distintas instituciones y propiciar la movilidad de estudiantes de licenciatura y posgrado en estas reas entre los pases de habla hispana y portugesa en latinoamrica. En esta ocasin contamos con la participacin de 48 resmenes, 31 presentaciones orales y 17 carteles que cubren reas tan diversas como PIXE, prdida de energa, nanomateriales, modificacin de materiales mediante haces de iones, entre otros temas. Esperamos que este evento en el hotel Iberostar en Playa del Carmen, Quintana Roo, Mxico sea en prembulo para que la Fsica Atmica y Molecular en america latina se vea fortalecida y resuferce sus lazos de unin. Agradecemos el apoyo parcial de las instituciones de la UNAM:

    Instituto de Ciencias Fsicas

    Instituto de Ciencias Nucleares

    Instituto de Fsica Facultad de Ciencias

    as como el apoyo de Connie Figueroa del hotel Iberostar, Patricia Rodrguez, Erika Ruz, y Adrian Dvila del ICF por su apoyo administrativo. El comit organizador

  • 3

    Programa

    1La recepcin/registro ser en el Saln Yucatan del hotel Iberostar. 2La reunin del comit internacional ser en el saln Yucatan. 3La cena ser en el Restaurante Mexicano del hotel Iberostar. 4Las sesiones orales y posters sern en el saln Yucatn.

    Horario Domingo Lunes Martes Mircoles

    8:00-8:45 Registro

    8:45-9:00 Inauguracin

    9:00-9:25 (Chair: Cabrera) R. Garca Molina (Chair: Mndez)

    J. Miranda (Chair: Behar)

    J. F. Dias

    9:25-9:50 Isabel Abril J. A. Reyes-Esqueda R. M. Papaleo

    9:50-10:15 Natalia Koval A. Crespo B. Fierro

    10:15-10:40 J. M. Fernndez I. Alencar J. E. Miraglia

    10:40-11:00 CAFE CAFE CAFE

    11:00-11:25 (Chair: Cruz) M. V. Moro (Chair: Recamier)

    M. Hatori (Chair: Grande)

    C. Montanari 11:25:11:50 Peter Koval A. P. L. Bertol S. A. Cruz

    11:50-12:15 M. Dingfelder P. L. Grande A. M. Jurez

    12:15-12:40 M. A. Quinto J. Ferrn J. I. Jimnez

    12:40-16:00 COMIDA COMIDA COMIDA

    16:00-16:25 (Chair: Juarez) N. R. Arista (Chair: Jimnez) E. C. Goldberg

    16:25-16:50 G. G. Marmitt A. Amaya

    16:50-17:15 M. Dapor N. Stolterfoht

    17:15-17:40 L. Sigaud SESION DE POSTERS4

    17:40-18:05 Reunin CI2

    18:05-18:30 Recepcin / Registro1

    18:30-20:00

    20:30-21:30 CENA3

  • 4Presentaciones Orales

    O1 Interaction of swift proton beams with materials of biological relevance ..................... 7 RafaelGarca-MolinaO2 Radial energy deposition in PMMA by secondary electrons generated by proton impact ............................................................................................................................... 8 IsabelAbrilO3 Vicinage Effect in the Energy Loss of a Hydrogen Dimer from TDDFT Calculations .. 9 NataliaE.KovalO4 Ionizacin de capas K y L de tomos pesados por impacto de electrones .............. 10 JosMa.Fernndez-VareaO5 Stopping cross sections of transition metals for H+ and He+ ions obtained from backscattering spectra in the range 10 keV to10 MeV ................................................... 11 MauricioV.MoroO6 Iterative computation of energy loss into electronic excitations ................................ 12 PeterKovalO7 Track structure and nanoparticles a case study ..................................................... 13 MichaelDingfelderO8 Traza de protones en la materia biolgica usando parmetros cunticos ................ 14 MicheleA.QuintoO9 Transferencia de energa cintica en colisiones de iones altamente cargados con lminas de carbono. ........................................................................................................ 15 NestorR.AristaO10 Diffusion in TiO2 films studied by electron- and ion-RBS ....................................... 16 GabrielG.MarmittO11 Comparison between experimental measurement and Monte Carlo simulation of the secondary electron energy spectrum of low order Poly(3-hexylthiophene-2,5-diyl) ....... 17 MaurizioDaporO12 Produo do diction de etileno por impacto de eltrons ....................................... 18 LucasSigaudO13 Secciones de produccin de rayos X L por impacto de iones pesados .................. 19

    Javier Miranda

    O14 Efecto del tamao y la composicin en la generacin de segundo armnico a partir de polvos de niobato de litio para diferentes longitudes de onda de excitacin: rol de la longitud de coherencia .................................................................................................... 20 AlejandroReyes-EsquedaO15 Formacin de nanopartculas metlicas en zafiro sinttico .................................... 21 AlejandroCrespo-SosaO16 Characterization of nanoparticles emitted by electronic sputtering of CaF2 ............ 22 IgorAlencarO17 Synthesis of InAs nanoprecipitates by low energy implantation followed by RTA .. 23 MasahiroHatori

  • 5O18 Influncia de coleo incompleta de carga em detector de Si(Li) na anlise de espectros PIXE para determinao experimental de parmetros atmicos ................... 24 AnaP.L.BertolO19 Alternative treatment for the energy-transfer and transport cross section in dressed electron-ion binary collisions ........................................................................................... 25

    Pedro L. Grande

    O20 Layer by Layer behavior of C60 during growth and sputter erosion. ...................... 26 Julio Ferrn

    O21 Signals of strong electronic correlation in ion scattering processes. ....................... 27 E.C.GoldbergO22 Estudio a 30 keV de procesos electrnicos en la colisin He++ + Ar .................... 28 AlejandroAmaya-TapiaO23 Ion guiding through insulating capillaries: Survey of experiment and theory .......... 29

    Nikolaus Stolterfoht

    O24 Fukushima: Passado, Presente e Futuro ................................................................ 30 Johnny F. Dias

    O25 On the radiolytic efficiency of high-energy ions confined in ultrathin polymer films 31 Ricardo M. Papalo

    O26 Nanoestructuras de carbono irradiadas por protones ............................................. 32 BernardoFierroO27 Sobre la difraccin cuntica que ocurre en colisiones rasantes de tomos neutros sobre aisladores .............................................................................................................. 33 JorgeE.MiragliaO28 Stopping power, estado del tema, tendencias e intereses ..................................... 34 ClaudiaMontanariO29 On the use of models of quantum confinement to study ion stopping in condensed matter. ............................................................................................................................. 35

    Salvador A. Cruz

    O30 Algoritmos de superresolucin aplicados a estudios de interaccin de plasmas con laseres ............................................................................................................................ 36 AntonioM.JurezO31 Espectroscopia lser sin ensanchamiento Doppler de las transiciones prohibidas por la aproximacin dipolar elctrica 5P3/2 -> 6Pj (j = 3/2, 1/2) en tomos trmicos de rubidio. ............................................................................................................................ 37 JosI.Jimnez

    Posters P1 Time-of-Flight Secondary Ion Mass Spectrometry beamline at the Ion Implantation Laboratory: Current status and perspectives .................................................................. 38 IgorAlencarP2 Compositional depth profile investigation of plasma doped Si/SiO2:As by Medium-Energy Ion Scattering ..................................................................................................... 39 IgorAlencar

  • 6P3 Valine decomposition by H+, He+ and N+ MeV ions .................................................. 40 CinthiaA.P.daCostaP4 Dinmica de electrones y ncleos dentro del modelo de orbitales gaussianos esfricos flotantes ........................................................................................................... 41 Luisa N. Trujillo LpezP5 Interaccin de sulfito de sodio con las bases nitrogenadas del ADN: Un estudio de dinmica molecular basado en primeros principios. ....................................................... 42 DanielMartnez-ZapataP6 Modificacin de superficies y pelculas delgadas por efecto de la irradiacin con iones a energas de MeV ................................................................................................ 43 LuisRodrguezFernndezP7 Medida das sees de choque de produo de raios X induzidas por ons pesados. ........................................................................................................................................ 44 FlviaFernandesP8 Prototipo para la deteccin de metales pesados en agua usando microplasmas .... 45 AdrianaLozanoP9 Estabilizacin de coherencia con entornos anidados: un estudio numrico usando modelos de Ising pateados ............................................................................................. 46 Carlos Gonzlez-GutirrezP10 Clculo del espectro y propiedades de un paquete de ondas ultrafro en una gua de onda con varias impurezas ........................................................................................ 47 RicardoMndez-FragosoP11 Characterization of resistive memories using NRA and micro-beam RBS .............. 48 Milena C. SulzbachP12 MeV-SIMS no Laboratrio de Implantao Inica IF-UFRGS ................................. 49 LianaA.B.NiekraszewiczP13 MEIS technique applied in 3D characterization of nanostructures .......................... 50 HenriqueTrombiniP14 Non-linear stopping powers of Al and Mo for H+ ions .............................................. 51 JosMa.Fernndez-VareaP15 Fluctuaciones dependientes de la fase en fluorescencia resonante intermitente ... 52 RicardoRomn-AncheytaP16 La prdida de energa de iones en ZnO .................................................................. 53 ClaudiaC.MontanariP17Estudiocomparativodelefectoumbralenladistribucindeenergaparaprotones,electronesypositronesusandoelmodelodielctrico...54ClaudioArchundi(NestorArista)PARTICIPANTES ........................................................................................................... 55

    ndice .............................................................................................................................. 57

  • 7O1 Interaction of swift proton beams with materials of

    biological relevance

    Rafael Garcia-Molina1, Pablo de Vera2, Isabel Abril3

    1Departamento de Fsica - Centro de Investigacin en ptica y Nanofsica, Regional Campus of International Excellence Campus Mare Nostrum,

    Universidad de Murcia, E-30100 Murcia, Spain 2School of Mathematics and Physics, Queens University Belfast, University Road,

    BT7 1NN, Belfast, Northern Ireland, UK 3Departament de Fsica Aplicada, Universitat dAlacant, E-03080 Alacant, Spain

    A review is provided of the interaction of swift proton beams with materials of biological relevance (liquid water, DNA...) and the subsequent generation of secondary electrons, which play a key role in the damage of tumour cells. By using the simulation code SEICS (Simulation of Energetic Ions and Clusters through Solids) [1], which combines both Monte Carlo and Molecular Dynamics methods, we provide a detailed account of the energy deposited as well as the geometrical evolution of the beam as a function of the target depth and nature, which is a central issue in hadron therapy. The SEICS code considers the most relevant interactions that take place between the projectile and the target constituents (electrons and nuclei), namely elastic collisions (affecting mainly the projectiles direction) and inelastic collisions (leading to either nuclear reactions or electronic energy loss). The dielectric formalism, suitably combined with a realistic description of the target electronic excitation spectrum provided by the MELF-GOS method [2], constitutes an excellent framework to calculate the energy deposited by the projectile through electronic excitations and ionisations. Nuclear reactions between the incident beam and the target nuclei have also to be taken into account, as they modify the otherwise only-electronic-energy deposition processes [3]. Knowing in detail the energy lost by the incident proton beam as a function of the target depth is essential because it considerably affects the features of the cascade of secondary electrons generated by the proton impact, which transport this energy in the nanometre and micrometre scale around the projectile track, until reaching the low energy values responsible of biomolecular damage [4]. References [1] R. Garcia-Molina, I. Abril, S. Heredia-Avalos, I. Kyriakou and D. Emfietzoglou, A combined

    molecular dynamics and Monte Carlo simulation of the spatial distribution of energy deposition by proton beams in liquid water, Physics in Medicine and Biology 56 (2011) 6457.

    [2] S. Heredia-Avalos, R. Garcia-Molina, J. M. Fernndez-Varea, I. Abril, Calculated energy loss of swift He, Li, B, and N ions in SiO2, Al2O3 and ZrO2, Physical Review A 72 (2005) 052902.

    [3] P. de Vera, I. Abril, R. Garcia-Molina, to be published. [4] L. Sanche, Low energy electron-driven damage in biomolecules, European Physical Journal D

    35 (2005) 367. Acknowledgements We acknowledge financial support by the Spanish Ministerio de Economa y Competitividad and the European Regional Development Fund (Project No. FIS2014-58849-P), as well as the Murcia Regional Agency of Science and Technology (project 19907/GERM/15). PdV acknowledges financial support from the European Unions FP7-People Program (Marie Curie Actions) within the ITN No. 608163 "ARGENT".

  • 8O2 Radial energy deposition in PMMA by secondary

    electrons generated by proton impact

    Isabel Abril1, Maurizio Dapor2, Pablo de Vera3, Rafael Garcia-Molina4

    1Departament de Fsica Aplicada, Universitat dAlacant, E-03080 Alacant, Spain 2European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*), Bruno

    Kessler Foundation, and Trento Institute for Fundamental Physics and Applications (INFN-TIFPA), I-38123 Trento, Italy

    3School of Mathematics and Physics, Queens University Belfast, University Road, BT7 1NN, Belfast, Northern Ireland, UK

    4Departamento de Fsica - Centro de Investigacin en ptica y Nanofsica, Regional Campus of International Excellence Campus Mare Nostrum, Universidad de Murcia, E-30100 Murcia, Spain

    The ionization yield of proton tracks in condensed systems reaches a maximum, known as the Bragg peak, close to the end of their trajectories, which allows a precisely controlled delivery of energy in the material by the beam. Along the path of the protons through the target, many electrons are generated, which produce a cascade of further ionizations and, consequently, a shower of secondary electrons. This work is devoted to the simulation of the radial energy deposition of the secondary electrons produced by swift protons in a sample of polymethylmethacrylate (PMMA). This material is used as a phantom for living tissues in hadron therapy, it is of relevance for microelectronics in CMOS technologies, and it is also used as a photoresist mask in electron beam lithography.

    The Monte Carlo track structure code SEED (Secondary Electron Energy Deposition) [1] simulates the complete slow-down of the entire cascade of generated secondary electrons, which includes the relevant interaction phenomena between the electrons and the condensed target, namely: elastic scattering (calculated by the Mott theory), the electron-electron inelastic scattering processes (performed within the dielectric formalism and the Mermin theory), and also the inelastic interactions of the incident electrons with phonons, and polarons (trapping phenomena).

    The SEED Monte Carlo code starts from a realistic description of the energy [2] and angular [3] distribution of the secondary electrons ejected by proton moving through PMMA, which are obtained by a semiempirical model based on the dielectric formalism and where a realistic electronic excitation spectrum of PMMA is accounted for. References [1] M. Dapor, I. Abril, P. de Vera, R. Garcia-Molina, Eur. Phys. J. D 69, 165 (2015) [2] P. de Vera, R. Garcia-Molina, I. Abril I, A. V. Solovyov, Phys. Rev. Lett. 110, 148104 (2013) [3] P. de Vera, R. Garcia-Molina, I. Abril, Phys. Rev. Lett. 114, 018101 (2015)

    Acknowledgements The authors thank financial support by the Spanish Ministerio de Economa y Competitividad and the European Regional Development Fund (Project No. FIS2014-58849-P), as well as the Murcia regional Agency of Science and Technology (project 19907/GERM/15). PdV acknowledges financial support from the European Unions FP7-People Program (Marie Curie Actions) within the ITN No. 608163 "ARGENT".

  • 9O3 Vicinage Effect in the Energy Loss of a Hydrogen

    Dimer from TDDFT Calculations

    Natalia E. Koval., D. Snchez-Portal., A. G. Borisov. and R. Dez Muio.

    Centro de Fsica de Materiales, CFM (CSIC-UPV/EHU) and Donostia International Physics Center, DIPC, San Sebastin, Spain

    Institut des Sciences Molculaires dOrsay, ISMO, CNRS-Universit Paris-Sud UMR 8214, Orsay Cedex, France

    In this work I will present a Time-Dependent Density Functional Theory (TDDFT) study of the vicinage effect in the energy loss of a hydrogen dimer passing thought a spherical nanocluster. The problem of the stopping of particles in matter, and in particular of the interference effect in the stopping of particles moving in close proximity to each other (the vicinage effect), is longstanding. Many experimental as well as theoretical studies have shown that the energy loss of a particle can be significantly modified in the presence of another particle in the vicinity of the first one [1-4]. From the point of view of the theory the vicinage effect is usually studied by using the dielectric formalism which can reasonably describe the energy loss only at high projectile energies. The real-time TDDFT that we use in this work is an ab-initio non-perturbative method which allows us to accurately calculate the energy loss of moving projectiles in the whole range of energies [5,6]. In my talk I will describe in detail the methodology we use. I will show as well our recent results of the fully three-dimensional study of the stopping power ratio for a hydrogen dimer in spherical clusters with the effective electronic density of SiO. I will discuss the importance of the coupled dynamic screening of the dimer inside the cluster and its effect in the stopping of two protons. The dependence of the stopping power on the orientation of the dimer will be discussed as well. Our theoretical results for the stopping power ratio of hydrogen are compared with recent experimental measurements and as I will show in my talk, the TDDFT results quantitatively agree with experimental values. References 1. Nstor R. Arista. NIMB, 164-165:108138, 2000. 2. M. Alducin, R. Dez Muio, and A. Salin. NIMB, 232:178183, 2005. 3. Z. L. Mikovi, Y.-N. Wang, and Y.-H. Song. NIMB, 256:5765, 2007. 4. S. M. Shubeita, P. L. Grande, J. F. Dias, R. Garcia-Molina, C. D. Denton, and I. Abril. Phys. Rev. B, 83:245423, 2011. 5. A. G. Borisov, J. I. Juaristi, R. D. Muio, D. Snchez-Portal, and P. M. Echenique, Phys. Rev. A 73:012901, 2006. 6. M. Quijada, A. G. Borisov, I. Nagy, R. Dez Muio, and P. M. Echenique. Phys. Rev. A, 75:042902, 2007. Acknowledgements We gratefully acknowledge Pedro Luis Grande for sharing with us some of his unpublished experimental data that served as a motivation for this theoretical work. This work has been partially supported by the Basque Departamento de Educacin, Universidades e Investigacin, the University of the Basque Country UPV/EHU (Grant No. IT-756-13) and the Spanish Ministerio de Economa y Competitividad (Grant No. FIS2013- 48286-C02-02-P). Authors acknowledge Donostia International Physics Center (DIPC) for funding and computer power.

  • 10O4 Ionizacin de capas K y L de tomos pesados

    por impacto de electrones J.M. Fernndez-Varea1,2, V.R. Vanin2, M.N. Martins2, N.L. Maidana2, A. Mangiarotti2,

    M.V. Manso Guevara3, S.F. Barros2, O.C.B. Santos2, J.A. Garca-Alvarez2, M.H. Tabacnics2, C.L. Rodrigues2, T.F. Silva2, M.F. Koskinas4, M.S. Pindzola5

    1 Facultat de Fsica, Universitat de Barcelona, Espaa 2 Instituto de Fsica, Universidade de So Paulo, Brasil

    3 Universidade Estadual de Santa Cruz, Bahia, Brasil 4 Instituto de Pesquisas Energticas e Nucleares, So Paulo, Brasil

    5 Department of Physics, Auburn University, Alabama, USA El acelerador microtrn de So Paulo dispone de una lnea que genera haces de electrones con energas entre 10 y 100 keV. En estos ltimos aos hemos utilizado este acelerador para medir secciones eficaces de ionizacin de capas K de Ag, Au y Bi y subcapas L de Au [1-4]. Para ello se han fabricado muestras muy delgadas depositadas sobre sustratos finos de carbono. Los rayos x emitidos despus de la ionizacin son colectados con espectrmetros HPGe y SDD cuya eficiencia de absorcin total ha sido evaluada usando un modelo analtico con parmetros ajustables determinados a partir de eficiencias medidas con fuentes radioactivas certificadas [5]. En los primeros experimentos [1-3] las incertidumbres en el grosor de la muestra, el ngulo slido del detector y el nmero de electrones incidente eran grandes y se opt por determinar las secciones eficaces normalizando la produccin de rayos x medida con secciones eficaces de emisin de bremsstrahlung tericas. En los experimentos ms recientes [4] el grosor se mide con precisin empleando espectrometra de retrodispersin Rutherford y la carga se obtiene integrando la corriente que llega a la Faraday cup y la que es dispersada por el blanco hacia las paredes de la cmara de vaco. Con estas mejoras logramos incertidumbres inferiores al 10% en las secciones eficaces absolutas. Asimismo, en el caso de subcapas L hemos desarrollado un mtodo de anlisis novedoso. Nuestras secciones eficaces experimentales estn en buen acuerdo con las predicciones de los formalismos DWBA [6] y SCADW [7] pero para las capas K de tomos muy pesados las discrepancias entre experimento y DWBA alcanzan el 15%. Esto puede ser debido a las simplificaciones introducidas en la evaluacin de los elementos de matriz de la interaccin transversal, que se calculan de manera ms rigurosa en el formalismo SCADW. References [1] J.M. Fernndez-Varea, V. Jahnke, N.L. Maidana, A.A. Malafronte, V.R. Vanin, J. Phys. B: At. Mol. Opt. Phys. 47 (2014) 155201. [2] S.F. Barros, V.R. Vanin, N.L. Maidana, J.M. Fernndez-Varea, J. Phys. B: At. Mol. Opt. Phys. 48 (2015) 175201. [3] V.R. Vanin, M.V. Manso Guevara, N.L. Maidana, M.N. Martins, J.M. Fernndez-Varea, Radiat. Phys. Chem. 119 (2016) 14. [4] S.F. Barros et al., in preparation. [5] S.F. Barros, N.L. Maidana, J.M. Fernndez-Varea, V.R. Vanin, X-Ray Spectrom. (accepted). [6] D. Bote, F. Salvat, Phys. Rev. A 77 (2008) 042701. [7] M.S. Pindzola, Phys. Rev. A 90 (2014) 022708.

    Agradecimientos. Este trabajo ha recibido el apoyo financiero de CNPq y FAPESP (Brasil) y del Ministerio de Economa y Competitividad (Espaa). JMFV agradece a la Universidade de So Paulo por una beca de Profesor Visitante.

  • 11O5 Stopping cross sections of transition metals for

    H+ and He+ ions obtained from backscattering spectra in the range 10 keV to10 MeV

    M. V. Moro1,2, D. Roth2, B. Bruckner2, T. F. Silva1,3, L. Lehner2,

    D. Primetzhofer4, P. Bauer2 and M. H. Tabacniks1 Institute of Physics, University of So Paulo, Rua do Mato 1371, 05508-090 So Paulo, Brazil

    Institut fr Experimentalphysik, Johannes-Kepler Universitt, Altenbergerstrae 69, A-4040 Linz, Austria 3Max-Planck-Institut fr Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

    4Department of Physics and Astronomy, Uppsala Universitet, Box 516, S-751 20 Uppsala, Sweden

    Accurate knowledge of electronic stopping cross sections (SCS) is important in many aspects of basic research and applications, like engineering, ion implantation and modification of materials, medical physics, ion beam analysis and for the validation of theoretical models and fundamental concepts [1,2]. Efforts have been taken to cover the lack of experimental data for many ion-target combinations and to understand why many experimental datasets in literature disagree [3]. In this contribution, electronic SCS data of transition metals (Nb, Hf, Ta) and Pt have been obtained from relative backscattering measurements (RBS and TOF-LEIS), by comparing the height ratios of spectra obtained for the materials of interest and for reference samples with similar atomic numbers [4]. In the evaluation, experimental height ratios were compared to corresponding ratios obtained from SIMNRA simulations [6], in an energy interval close to the kinematic onset [5]. In the simulations, the SCS of the reference was taken from literature; for the scattering potential Andersen screening was used [7] and the dual scattering model was employed. Additionally, especially for low energy data, Monte Carlo simulations [8] were performed allowing for plural and multiplescattering effects [9]. This methodology has been tested comparing SCS data of Al against accurate transmission data [1]. Experimental results for transitions metals (Nb, Hf, Ta) and Pt were obtained for H+ and He+ ions in the energy range from 500 eV up to several MeV. The overall uncertainties range from approximately 5% for the high energy data to 10 % in the LEIS regime, mainly due to uncertainties of the reference SCS data and to fluctuations of the primary beam current. With this approach, we were able to: i) use bulk samples (easy to prepare/produce) and ii) measure in three different energy ranges at three different laboratories: Linz/Austria, Sao Paulo/Brazil and Uppsala/Sweden. In addition, the obtained SCS data rise the question how the energy loss process is correlated with band structures especially for transition metals (d-bonded electrons) [10,11,12]. Finally, the results can be used to improve the international database as required by the IBA community [13]. [1] M. V. Moro, T. F. Silva et al., Phys. Rev. A 93 (2016) 022704. [2] E.E. Quashie, B.C. Saha, and A.A. Correa, Phys. Rev. B 94 (2016) 155403. [3] H. Paul, Nucl. Instrum. Methods Phys. Res., Sect. B 268, (2010) 3421. [4] E. I. Sirotinin, A. F. Tulinov et al., Nucl. Instrum. Meth. B 4 (1984) 337. [5] D. Roth, D. Goebl et al., Nucl. Instrum. Meth. B 317 (2013) 61 [6] M. Mayer, Proceedings of the 15th ICAARI, AIP Conf. Proc.475 (1999) 541. [7] H.H. Andersen, F. Besenbacher, P. Loftager, and W. Mller, Phys. Rev. A 21 (1980) 1891. [8] J.P. Biersack, E. Steinbauer and P. Bauer, Nucl. Instr. Meth. B 61 (1991) 77. [9] D. Primetzhofer, S.N. Markin et al., Nucl. Instr. Meth. B 269 (2011) 1292. [10] D. Goebl, D. Roth, and P. Bauer, Phys. Rev. A 87 (2013) 062903. [11] D. Primetzhofer, Phys. Rev. B 86 (2012) 094102. [12] S.N. Markin, D. Primetzhofer et al., Phys. Rev. B 78 (2008) 195122. [13] C. Jeynes and J. L. Colaux, Analyst 141(2016) 5944.

  • 12

    O6 Iterative computation of energy loss into electronic excitations

    Peter Koval*, Mathias Per Ljungberg*, Daniel Sanchez-Portal**

    * Donostia International Physics Center,

    Paseo Manuel Lardisabal, 4, Donostia-San Sebastian, Spain ** Centro de Fisica de Materiales,

    Paseo Manuel Lardisabal, 5, Donostia-San Sebastian, Spain A method is presented to compute the dielectric function of extended systems using linear response time-dependent density functional theory (TDDFT). Atomic orbitals are used to determine the KS eigenstates as implemented in SIESTA package [1]; and an auxiliary localized product basis set is used to expand the (linear) response function. The construction of the product basis is a crucial part of the method, because the properties of the product basis determine the accuracy and computational performance of the method. We test two approaches for the product basis construction: a dominant products basis set that expands the atomic-orbital products individually for each atom pair; and an atom-centered product basis set, which uses the local orbital products (generated within the same atom) to expand the other products. Although both product basis sets are capable of accurately describe the response functions, they differ substantially in their spatial connectivity: although the number of atom-centered functions needed for a given system is much smaller than that of the dominant products, the latter are connected to considerably fewer atomic-orbital products. Thus, in order to set up a competitive computational procedure it is beneficial to make use of both basis sets in a complementary way [2]. In this work, the electron-energy loss function is directly obtained by an iterative Krylov-subspace method, solving a Petersilka-Gossman-Gross equation for the interacting response function. The atom-centered basis is used to discretize the TDDFT interaction kernel, while the dominant product basis is used in the application of the non-interacting response function to a vector. The method is applied to graphene and bulk silicon and the computed spectra are compared to existing plane-wave based approaches [3]. Finally, to demonstrate the merits of the method for systems with large unit cells, where it will be most competitive, we compute electron-energy loss spectra for several organic crystals such as C60, TTF and TCNQ. References [1] E.Artacho, E.Anglada, O.Dieguez, J.D.Gale, A.Garcia, J.Junquera, R.M.Martin, P.Ordejon, J.M.Pruneda, D.Sanchez-Portal and J.M.Soler, J. Phys.: Condens. Matter 20 (2008) 064208. [2] Peter Koval, Federico Marchesin, Dietrich Foerster and Daniel Sanchez-Portal, J.Phys.: Condens. Matter 28 (2016) 214001. [3] Peter Koval, Mathias Per Ljungberg, Dietrich Foerster, Daniel Sanchez-Portal Nuclear Instruments and Methods in Physics Research B 354 (2015) 216-219.

  • 13

    O7 Track structure and nanoparticles a case study

    Michael Dingfelder, Jacek Teller, Robert A. McLawhorn, and Jefferson L. Shinpaugh

    Department of Physics,

    East Carolina University, Mailstop 563, Greenville, NC 27858, EEUU Nanometer size structures including nanoparticles of all kind enter radiation biology and medical physics applications. Understanding and modeling the effects of these nano-structures on radiation transport and biological response is challenging as standard tools and procedures available are based on standard assumptions that may not be suitable for a nanometer scale. Standard radiation transport codes, including track structure codes are designed for bulk material, or indefinite 3-dimensional transport and for radiation equilibrium. Track structure codes are also very limited in available materials. Typically, track structure simulations use water in either, the liquid, vapor, or solid phase and use density scaling to simulate other materials. Nanoparticles often contain metals and other high-Z materials. They are small in size with at least one dimension in the order of 1 10 nanometer. Furthermore, the surface to volume ratio is high compared to simple geometrical interfaces. With this in mind, this communication will investigate a more realistic modeling of radiation transport through a material containing nanoparticles. Currently, the track structure code PARTRAC can simulate track structures of fast protons and electrons in liquid water and copper. It is planned to also calculate and implement interaction cross sections for the transport of fast protons and electrons in gold. Secondary electron emission spectra from thin gold foils after fast proton and light ion impact have been measured at the ECU accelerator laboratory. Previous studies on electron transport in copper showed that energy loss changes for bulk and surface models. We will investigate the effects of geometry and bulk versus surface models on the radiation transport for realistic nanoparticle structures. Focus will be on physical properties like energy depositions, and (non)-equilibrium transport effects.

  • 14O8 Traza de protones en la materia biolgica usando

    parmetros cunticos Michele A. Quinto a, Juan M. Montia, Philippe F. Weckb, Omar A. Fojona, Jocelyn

    Hanssena, Christophe Championc and Roberto D. Rivarolaa

    aInstituto de Fsica Rosario, CONICET, Universidad Nacional de Rosario, Rosario, Argentina bSandia National Laboratories, Albuquerque, NM 87185, USA

    cUniversit de Bordeaux, CNRS/IN2P3, Centre dEtudes Nuclaires de Bordeaux Gradignan, Gradignan, France

    La comprensin de los mecanismos fsicos que producen deposicin energtica en la materia biolgica sometida a irradiacin con haces de iones, constituye un tema de inters fundamental en radiobiologa y radioterapia, considerando en particular que permiten una mejor identificacin de las lesiones crticas del ADN. Los cdigos de estructura de traza Monte Carlo representan instrumentos convenientes y poderosos para describir el frenamiento de las partculas ionizantes en la materia biolgica. En el presente trabajo, detallamos el cdigo de estructura Monte Carlo, llamado TILDA-V, el cual es alimentado por clculos mecnico-cunticos de secciones eficaces diferenciales mltiples y totales. Estas secciones describen todos los procesos inelsticos y elsticos que ocurren en la traza de protones en agua y en ADN [1]. TILDA-V (un acrnimo de Transport d'Ions Lourds Dans Aqua et Vivo) es una extensin de un cdigo desarrollado previamente por Champion et al. [2]. En esta nueva versin se incluyen todas las interacciones de haces de protones y de hidrgeno en agua, as como tambin en las nucleobases de ADN y en el esqueleto azcar-fosfato [1]. Se considera una descripcin realista del medio biolgico, modelizando un nucletido tpico de ADN hidratado, a saber, un par de nucleobases ms el esqueleto azcar-fosfato, ambos rodeado por una cscara de hidratacin constituida por 18 molculas de agua. Se compararn los patrones de depsito energtico en agua y en ADN.

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    Referencias [1] M. A. Quinto, J. M. Monti, M. E. Galassi, P. F. Weck, O. A. Fojn, J. Hanssen, R. D. Rivarola y C. Champion, J. Phys.: Conf. Series. 583, 012049 (2015). [2] C. Champion, A. LHoir, M.-F. Politis, P. D. Fainstein, R. D. Rivarola y A. Chetioui, Radiat. Res. 163, 222-231 (2005).

  • 15O9 Transferencia de energa cintica en colisiones

    de iones altamente cargados con lminas de carbono.

    N. R. Arista1 y R. Lake2

    1Divisin Colisiones Atmicas, Centro Atmico Bariloche, Bariloche, Argentina 2Lawrence Berkeley National Laboratory, Livermore, CA, USA

    Se propone un modelo terico para describir la transferencia de energa cintica de iones pesados y mltiplemente cargados al atravesar lminas y membranas ultradelgadas de carbono. Se propone un modelo para el potencial de interaccin entre iones incidentes y tomos de C. La transferencia de energa elstica se calcula utilizando dos opciones: la aproximacin de ngulos pequeos o integrando en forma exacta la ecuacin de movimiento. El modelo permite explicar la dependencia con la carga del ion observada en recientes experimentos con iones de Xe al atravesar membranas de C con espesores de 1 nm (Wilhelm et al, Phys. Rev. Lett. 112, 153201 [2014]), y la prdida media de energa de iones de O, Ar, Kr, Xe y Au, al atravesar lminas de C de 10 nm de espesor (Schenkel et al, Phys. Rev. Lett. 79, 2030 [1997]).

  • 16O10 Diffusion in TiO2 films studied by electron- and

    ion-RBS

    G. G. Marmitt1, S.K. Nandi2, D.K. Venkatachalam2, R. G. Elliman2, M. Vos3 and P.L. Grande1

    1 Instituto de Fsica, Universidade Federal do Rio Grande do Sul

    2 Electronic Materials Engineering Department, The Australian National University 3 Atomic and Molecular Physics Laboratories, The Australian National University

    Electron Rutherford Backscattering (ERBS) is a technique that depends on the recoil energy transferred from the scattering electron to a nucleus in a large-angle deflection. This energy transfer depends on the mass of the scattering atom. Analysing the energy of the scattered electrons reveals thus which atoms are present in the near surface layer [1, 2].

    In simple cases where there are 2-3 separate peaks due to different elements that do not overlap one can simply fit the spectra with the corresponding number of Gaussians. As this work shows, fitting of the data allows for very precise thickness and compositional determination. Among other examples [3], the analysis of a Si3N4 layer on TiO2 is particularly interesting. In this case the peaks overlap strongly, and show that highly consistent estimates of the thickness of the Si3N4 film are obtained for different measurement geometries. This procedure was then applied to the study of oxygen auto-diffusion through the use of isotopic marking, in an attempt to obtain the depth profile distribution attributed to the diffusion. High-resolution measurement of the energy of electrons backscattered from oxygen atoms makes it possible to distinguish between 18O and 16O isotopes as the energy of elastically scattered electrons depends on the mass of the scattering atom. Thermal annealings for 5 minutes at 500 800C in Ar atmosphere were conducted on our samples. Under these conditions, we were able to determine the activation energy for O self-diffusion in TiO2 at about 1.05 eV. By thermally treating samples for different times (5 100 min.) at a fixed temperature (650C), the diffusion regularity was also studied. The Arrhenius plot of diffusion length versus time exhibits two regions, suggesting that different diffusion mechanisms are involved. In order to cross check the results, RBS experiments were also conducted. Similarly with the ERBS spectra, oxygen peak shifts were also observed here. Then, simulations using PowerMEIS were performed considering the same diffusion profiles obtained by ERBS. The simulations agree beautifully with the RBS spectra, sign of a consistent procedure. References. [1] M. Went and M. Vos, Appl. Phys. Lett. 90, 072104 (2007). [2] M. Went and M. Vos, Nuclear Instruments and Methods in Physics Research Section B 266, 998 (2008). [3] G.G. Marmitt, L.F.S. Rosa, S.K. Nandi, and M. Vos, J. Electron Spectrosc. Relat. Phenom. 202, p. 2632 (2015). [4] E. Gale, Semicond. Sci. Technol. 29, 104004 (2014).

  • 17O11 Comparison between experimental measurement

    and Monte Carlo simulation of the secondary electron energy spectrum of low order Poly(3-hexylthiophene-2,5-

    diyl)

    Maurizio Dapor1, Robert C. Masters2, Ian Ross3, David Lidzey4, Andrew Pearson5, Isabel Abril6, Rafael Garcia-Molina7, Jo Sharp2, Marek Unovsk8,

    Tomas Vystavel8, Cornelia Rodenburg2

    1European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-FBK) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), via Sommarive 18, I-

    38123 Trento, Italy 2Department of Materials Science and Engineering, University of Sheffield, Mappin Street,

    Sheffield S1 3JD, UK 3Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street,

    Sheffield S1 3JD, UK 4Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield, S3

    7RH, UK 5Department of Physics, University of Cambridge, Cavendish Laboratory, 19 JJ Thomson

    Avenue, Cambridge CB3 0HE, UK. 6Departament de Fsica Aplicada, Universitat dAlacant, E-03080 Alacant, Spain

    7Departamento de Fsica - Centro de Investigacin en ptica y Nanofsica, Regional Campus of International Excellence Campus Mare Nostrum, Universidad de Murcia, E-30100 Murcia,

    Spain 8FEI Company, Vlastimila Pecha 1282/12, 627 00 Brno, Czech Republic

    The characterization of polymers is a very complex problem due, in particular, to beam induced radiation damage and charging phenomena. Poly(3-hexylthiophene-2,5-diyl), commonly known as P3HT, is a polymer widely used in organic electronics. In this work we present both an experimental measurement and a Monte Carlo simulation, performed by using the Secondary Electron Energy Distribution (SEED) code, of the shape of the secondary electron energy distribution of the low order semi crystalline polymer regioregular P3HT. Our comparison of simulated and experimental secondary electron spectra shows an excellent agreement, revealing a peak followed by a broad shoulder, a shape that we attribute to the combined effect of the band-gap and of a filtering effect. We experimentally determined both the filtering effect, related to the working distance, and the band gap. The Monte Carlo simulation allowed us evaluating the minimum depth of provenience of the emitted secondary electrons in our experiment, which is about 2.5 nm for low order P3HT. Acknowledgements The authors wish to thank Professor A. M Donald, University of Cambridge, for discussions and express their warm gratitude to Professor A. Howie, University of Cambridge, for the stimulating comments and helpful suggestions with regards to future developments. MD acknowledges the support of the Leverhulme Trust through the Visiting Professorship (VP1-2014-011) that made this project possible. IA and RGM thank partial financial support by the Spanish Ministerio de Economa y Competitividad (Project FIS2014-58849-P) and the Murcia Regional Agency of Science and Technology (project 19907/GERM/15). CR thanks EPSRC for funding under grant EP/N008065/1.

  • 18O12 Produo do diction de etileno por impacto

    de eltrons

    L. Sigaud1 e E. C. Montenegro2

    1Instituto de Fsica, UFF (Universidade Federal Fluminense), 24210-346, Niteri, Brasil 2Instituto de Fsica, UFRJ (Universidade Federal do Rio de Janeiro), 21941-972, Rio de Janeiro,

    Brasil Apesar de ons moleculares duplamente carregados serem, possivelmente, um fator crucial para a compreenso de processos fsico-qumicos de meios energizados e atmosferas planetrias, muito pouco se sabe sobre as sees de choque de produo de dictions de molculas simtricas, devido dificuldade intrnseca de se separar fragmentos com mesma razo massa/carga, como o caso de C2H4++ e CH2+, em um espectro de tempo de voo. Alm disso, seus prprios mecanismos de produo e sua possvel estabilidade, ainda no so conhecidos, levantando a questo se processos ps-colisionais podem desempenhar algum tipo de papel e, em caso positivo, qual seria sua relevncia para a produo de dictions metaestveis. Para conseguir diferenciar entre essas duas espcies, a tcnica DETOF foi empregada. Resumindo, o aparato experimental utilizado consiste de um canho de eltrons pulsado operando na faixa de 25 a 800 eV e um espectrmetro de tempo de voo padro acoplado a uma clula gasosa. A tcnica DETOF (Delayed Extraction Time-Of-Flight) consiste em um aumento sistemtico do tempo de atraso entre o feixe de eltrons e o campo eletrosttico que guia os fragmentos moleculares para dentro do tubo de tempo de voo, de forma que fragmentos mais rpidos tem tempo de voo livre o suficiente para deixar a regio de coleta. Assim, fragmentos moleculares inicos mais rpidos deixam de ser detectados, e esse tempo de atraso funciona como um seletor de velocidades. Como o diction C2H4++ permanece com uma distribuio de energia Maxwell-Boltzmann, ele pode ser separado do fragmento CH2+, que ganha energia cintica na quebra da molcula. Com isso, foi-se capaz de determinar a seo de choque absoluta para a produo do diction de etileno por impacto de eltrons pela primeira vez. Atravs da observao da razo entre C2H4++ e C2H4+ para as sees de choque experimentais obtidas, pode-se perceber claramente que, aps a razo entre as sees de choque atingir seu mximo em torno de 100 eV do eltron incidente, h uma queda no valor da razo mencionada, at se estabilizar em um valor constante para 500 eV e energias mais altas. Esse valor constante um indicativo da formao do C2H4++ por um processo de produo de vacncia simples, uma vez que, em processos de dupla ionizao, a seo de choque decresce mais rapidamente do que em processos de ionizao simples (acima de aproximadamente 100 eV). Logo, o diction de etileno pode ser formado tanto por mecanismos de produo de dupla vacncia (duplo impacto direto) quanto de vacncia simples (processos ps-colisionais similares a um decaimento Auger). Uma comparao com resultados anteriores obtidos para as molculas de oxignio e nitrognio, em trabalhos recentes, tambm ser feita. Esses resultados indicam que a molcula de oxignio teria o processo com produo de vacncia simples seguido de emisso eletrnica por desexcitao ps-colisional como o principal para a formao do O2++.

  • 19O13 Secciones de produccin de rayos X L por impacto

    de iones pesados

    Javier Miranda

    Instituto de Fsica, Universidad Nacional Autnoma de Mxico, Ap. Postal 20-364, lvaro Obregn, 01000 Ciudad

    de Mxico, Mxico Como resultado de un programa a largo plazo, se midieron secciones de produccin de rayos X L de los elementos Ce, Nd, Sm, Eu, Gd y Dy, inducidos por el impacto de iones de 4He+, 7Li2+, 8Be2+, 10B2+, 14N2+,12C3+, 16O3+ y 19F3+, cuyas energas de incidencia varan entre 0.50 MeV/u y 0.75 MeV/u. Se comparan con los clculos tericos usando la teora ECPSSR (que modifica la Aproximacin de Onda Plana de Born, PWBA). Algunas correcciones, como ionizacin mltiple del tomo blanco (MI), captura electrnica de capas internas de los iones incidentes (CE), tomo Unido (UA) y teoras de acoplamiento intra-capas (IS), se aadieron al modelo ECPSSR. Se encontr que la teora no describe exactamente los resultados experimentales para todos los casos. Adems, se hizo una compilacin de datos experimentales existentes para todos estos proyectiles, con el fin de encontrar curvas universales para las secciones produccin de rayos X de la lnea La (L3M4 + L3M5). ste se basa en un parmetro de velocidad reducida RL . En este esquema, los datos experimentales siguen curvas bien definidas para cada ion. Tambin se sugiere un escalamiento similar de la lnea Lg (L2N4 + L1N2 + L1N3 + L1O3 + L1O2 + L2N1 + L2O4), basndose en un parmetro diferente de velocidad reducida RL 2,1 . Los resultados parecen ser aplicables para casi todas las combinaciones de proyectil-blanco estudiadas en este trabajo, demostrando la necesidad de realizar ms estudios tericos en este sentido.

  • 20O14 Efecto del tamao y la composicin en la

    generacin de segundo armnico a partir de polvos de niobato de litio para diferentes longitudes de onda de

    excitacin: rol de la longitud de coherencia

    Oswaldo Snchez-Dena*, Emma V. Garca-Ramrez*, Csar D. Fierro-Ruiz**, Enrique Vigueras-Santiago***, Rurik Faras**, Alejandro Reyes-Esqueda*

    * Instituto de Fsica,

    Universidad Nacional Autnoma de Mxico, Mxico, Cd. Mx. 04510 ** Universidad Autnoma de Ciudad Jurez,

    Av. del Charro 450 Norte, Ciudad Jurez, Chihuahua, 32310 *** Universidad Autnoma del Estado de Mxico,

    Paseo Coln esquina Paseo Tollocan, Toluca, Estado de Mxico, 50000 Sistemas nanocristalinos de niobato de litio, producidos mediante una reaccin mecano-qumica, fueron sometidos a un estudio espectroscpico no lineal para estudiar la generacin de segundo armnico (GSA) a partir de ellos en el rango de longitudes de onda fundamentales de 800-1300 nm, con un paso de 10 nm. Mediante el control de la composicin y el tamao de partcula de las muestras estudiadas, se pudo maximizar la GSA para una longitud de onda especfica dentro de este rango, lo cual puede entenderse usando el concepto de longitud de coherencia. De igual manera, se corrobor el ordenamiento aleatorio de los nanocristales mediante la obtencin de la intensidad de GSA como funcin de la polarizacin de la luz incidente. Mediciones de esparcimiento mostraron la no existencia de empatamiento de fases en las muestras estudiadas. Finalmente, se obtuvo un valor efectivo de la no linealidad de alrededor de 6 pm/V. Resultados preliminares muestran un posible aumento de la seal mediante la orientacin de los nanocristales usando un campo externo. Agradecimientos Apoyo de PAPIIT-UNAM mediante el proyecto IN117116 y de la RED PRODEP-SEP Compuestos polimricos, propiedades y aplicaciones 2015-2016.

  • 21O15 Formacin de nanopartculas metlicas en

    zafiro sinttico

    Alejandro Crespo-Sosa, Mara-Luisa Garca-Betancourt, Rebeca Rojas-Granados, Pablo Mota-Santiago

    Instituto de Fsica,

    Universidad Nacional Autnoma de Mxico, Circuito de la investigacin s/n, Ciudad de Mxico, Mxico

    Hoy en da es bien conocido que las propiedades de la materia a nivel nanoscpico son interesantes por la posibilidad de controlar sus propiedades fsicas y qumicas por medio de controlar a su vez su tamao y su forma. En particular, las nanopartculas metlicas dentro de materiales dielctricos transparentes son interesantes por sus propiedades pticas, que en su mayora estn determinadas por la llamada resonancia local del plasmn de superficie. En este trabajo se presentan los resultados de la obtencin y deformacin de nanoparticulas de Ag y de Au en zafiro sinttico producidas por medio de implantacin de iones y su posterior calentamiento en un horno con una atmsfera controlada. La posible utilizacin en aplicaciones tecnolgicas de estos sistemas, depende fuertemente del control del tamao de las nanopartculas en ellos, por lo que, gran parte del esfuerzo ha sido en mejorar la uniformidad de tamao de las mismas. En esta presentacin se har nfasis en la importancia que tienen todos los parmetros durante el proceso de fabricacin, la implantacin y el tratamiento trmico. Agradecimientos. Los autores agradecen a Karim Lpez, Francisco Jaimes y Mauricio Escobar por la operacin del acelerador Pelletron; a Juan Gabriel Morales por la preparacin de muestras; y a Jaqueline Caetas, Roberto Hernndez y Carlos Magaa por la operacin de los microscopios electrnicos. Este Proyecto ha sido financiado principalmente por DGAPA-UNAM (IN108113) y CONACyT (178141)

  • 22O16 Characterization of nanoparticles emitted by

    electronic sputtering of CaF2 I. Alencara,, M. Hatoria, H. Trombinia, G. G. Marmitta, P. L. Grandea, J. F. Diasa,

    R. M. Papalob, W. Assmannc, M. Toulemonded, C. Trautmanne,f

    aInstituto de Fsica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves 9500, 91501-970 Porto Alegre, Brazil

    bDepartamento de Fsica, Pontifcia Universidade Catlica do Rio Grande do Sul, Av. Ipiranga 6681, 90619-900 Porto Alegre, Brazil

    cSektion Physik, Ludwig-Maximilians-Universitt Mnchen, Am Coulombwall 1, 85748 Garching, Germany

    dCentre de Recherche sur les Ions, les Matriaux et la Photonique, B. H. Becquerel, 14070 Caen, France

    eMaterialforschung, Helmholtzzentrum fr Schwerionenforschung, Planckstr. 1, 64291 Darmstadt, Germany

    fFachbereich Materialwissenschaften, Technische Universitt Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt, Germany

    Electronic sputtering of CaF2 induced by 180 MeV Au ions is investigated by the catcher technique, where high-purity surfaces collect the ejecta at a constrained distance from the target. These surfaces are analyzed by Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Medium-Energy Ion Scattering (MEIS), indicating the presence of sputtered nanoparticles (np). While np diameters obtained by TEM display a bimodal distribution, AFM show that the larger particles are composed of aggregates. These complementary techniques suggest the emission of spherical np. Depending on the areal density, they are isolated, overlap or completely coat the catcher surface as an heterogeneous film. For the case of isolated np, it is shown that the MEIS spectrum is properly described only when one considers the case of partially-buried particles. In this way, the content of collected Ca atoms at each catcher can be evaluated from diameter and height distributions. These values are smaller than direct estimates from ion scattering analyses when the areal density is low, but a simple correlation between the data allows its correction. By performing measurements at different collection angles, the angular distribution of differential sputter yield as well as the total yield are determined. Independent on the angle of beam incidence, a jet-like component normal to the sample surface is observed, similarly to previous investigations on LiF. However, the total yields for Ca atoms are much lower than those observed for Li atoms, possibly as a consequence of the difference in sublimation energy of CaF2 and LiF crystals. Acknowledgements This work was financially supported by Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES).

  • 23O17 Synthesis of InAs nanoprecipitates by low energy

    implantation followed by RTA

    M. Hatori1,2, B. Canut1, M.A. Sortica1,2, J.F. Dias2, N. Chauvin1, J. M. Bluet1

    1Universit Claude Bernard Lyon 1, Institut des Nanotechnologies de Lyon INL-IMR5270, F-

    69621 Villeurbanne, Lyon, France

    2Instituto de Fsica, Universidade Federal do Rio Grande do Sul (IF-UFRGS), Av. Bento Gonalves 9500, 91501-970, Porto Alegre (RS), Brazil

    The production of nanocrystals based on compound III - V semiconductors embedded in a semiconductor matrix with higher band gap is of great interest for optoelectronic devices since the pronounced quantum confinement effects of such materials allow tuning their light emission by controlling the size of the nanocrystals. Although the molecular beam epitaxy (MBE) is the most used technique to produce such nanostructures, the combination of ion implantation and thermal annealing has proved to be an interesting alternative.

    In recent years there has been a lot of activity towards compound III V semiconductors, with particular attention to InAs nanocrystals obtained through ion implantation. The aim of the present work is to investigate the formation and the structural and optical properties of InAs clusters obtained through sequential implantation of As and In ions in Si single crystals , followed by post-irradiation rapid thermal annealing (RTA).

    To that end, Si wafers were implanted at 500C with 30 keV As ions and 35 keV In ions with different fluences. The samples were annealed for different durations at temperatures ranging from 700C up to 1000C. Outdiffusion of As and In species was evidenced for annealings performed at the highest temperatures. To limit this effect, samples were annealed face to face in order to minimize the material loss.

    Complementary techniques like photoluminescence (PL), Raman spectroscopy, Rutherford backscattering spectrometry (RBS) and scanning electron microscopy (SEM) were employed to characterize the samples. Furthermore, transmission electron microscopy (TEM) will be performed to obtain refined structural information of the InAs clusters.

  • 24O18 Influncia de coleo incompleta de carga em detector de Si(Li) na anlise de espectros PIXE para determinao experimental de parmetros atmicos

    A.P.L. Bertol(1), P.C. Chaves(2), R. Hinrichs(3), M.A. Reis(2,4) and M.A.Z. Vasconcellos(1)

    (1) Instituto de Fsica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves, 9500

    Porto Alegre, RS, Brasil (2) C2TN, Instituto Superior Tcnico, Universidade de Lisboa, Portugal

    (3) Instituto de Geocincias, Universidade Federal do Rio Grande do Sul (4) IEQUALTECS, Lda, R. Dr Francisco S Carneiro, 36, 2500-065 S. Gregrio CLD, Portugal

    Sees de choque de produo de raios X de subcamadas L induzidas por prtons e partculas alfa so geralmente obtidas a partir da intensidade das linhas caractersticas em espectros adquiridos com detectores do tipo Si(Li) [1, 2]. Os valores apresentados na literatura, apesar de indicarem incertezas experimentais da ordem de 10%, variam entre si em torno de 25%. Uma das possveis razes dessa discrepncia a prtica comum de negligenciar os efeitos de coleo incompleta de carga no ajuste dos picos. Esse fenmeno gera uma cauda na regio de energias mais baixas que o pico caracterstico. Em espectros de linhas L, a sobreposio de linhas provenientes da ionizao de diferentes subcamadas muito marcante. Portanto, contagens que deveriam ser associadas cauda de um pico intenso podem ser erroneamente atribudas a linhas menores. Neste trabalho discutimos como o ajuste das linhas L de espectros PIXE de Hf e Au considerando coleo incompleta de carga interfere na determinao experimental de parmetros atmicos como seo de choque de produo de raios X e razo de intensidade entre linhas. Espectros PIXE de linhas L de filmes finos de Hf e Au foram obtidos com o detector de Si(Li) (e2V Scientific Instrument, modelo Sirius 80) da linha de PIXE no Tandetron 3 MV (High Voltage Engineering) do Laboratrio de Implantao Inica (IF- UFRGS-Brasil). Foram usados feixes de prtons (energias entre 0,7 e 4,4 Mev) e partculas alfa (energias entre 3 e 6,5 MeV). Os filmes finos foram depositados usando o sistema de magnetron sputtering (AJA International ATC ORION 8 UH) no Laboratrio de Conformao Nanomtrica (IF-UFRGS). O ajuste da funo resposta do detector e a anlise dos espectros foram feitos usando o cdigo DT2 [3] no Centro de Cincias e Tecnologias Nucleares, Instituto Superior Tcnico, Universidade de Lisboa, Portugal. Foi encontrado que, na situao em que a cauda mais evidente (linhas Lg de Au), ela se estende aproximadamente 700 eV abaixo da energia do centro do pico, com at 3% da sua intensidade. A resoluo tpica de um detector de Si(Li) de 150 eV, valor semelhante separao entre as linhas L. Alm disso, a maioria das linhas possui intensidade menor que 10% da linha intensa mais prxima (La1,2, Lb1 ou Lg1), principalmente as linhas provenientes da ionizao da subcamada L1. Assim, a comparao de ajustes analisados com e sem a funo resposta do detector mostrou que a cauda desempenha papel importante na separao da intensidade entre as linhas, influenciando a determinao de sees de choque de produo de raios X, e fundamental para a determinao experimental de razes de intensidade entre linhas. References [1] A.P.L. Bertol, J. Trincavelli, R. Hinrichs, M.A.Z. Vasconcellos, Nuclear Instruments and Methods in Physics Research Section B (318) 2014, 19. [2] A.P.L. Bertol, R. Hinrichs, M.A.Z. Vasconcellos, Nuclear Instruments and Methods in Physics Research Section B (363) 2015, 28. [3] M.A. Reis, P.C. Chaves, A. Taborda, J.P. Marques, N.P. Barradas, Nuclear Instruments and Methods in Physics Research Section B (318) 2014, 65.

  • 25O19 Alternative treatment for the energy-transfer and transport cross section in dressed electron-ion binary

    collisions

    P.L. Grande

    Ion Implantation Laboratory, Instituto de Fsica, Universidade Federal do Rio Grande do Sul, 9500 Avenida Bento Gonalves, CP 15051,

    CEP 91501-970, Porto Alegre, Rio Grande do Sul, Brazil

    A formula [1] for determining the electronic stopping power and the transport cross section in electron-ion binary collisions is derived from the induced density for spherically symmetric potentials using the partial-wave expansion. In contrast to the previous one found in many textbooks, the present formula converges to the Bethe and Bloch stopping-power formulas at high ion velocities and agrees rather well with experimental stopping-power data, as shown here for Al, C, and H2O targets. It can be employed in plasma physics and particularly in any application that requires electronic stopping-power values of quasifree electrons with high accuracy References [1] P.L. Grande, Phys. Rev. A 94, 042704 (2016)

  • 26O20 Layer by Layer behavior of C60 during growth

    and sputter erosion.

    Julio Ferrn

    Instituto de Fsica del Litoral (Universidad Nacional del Litoral - CONICET), Gemes 3450, (3000) Santa Fe, Argentina,

    and Departamento de Materiales, Facultad de Ingeniera Qumica, Universidad Nacional

    del Litoral, Santiago del Estero 2829. (3000) Santa Fe, Argentina.

    In this work we combine Auger Electron Spectroscopy (AES), Energy Loss

    Spectroscopy (ELS), Monte Carlo and Molecular Dynamics, to study the growth, and thermally and ion sputter induced desorption of C60 over different substrates, namely Cu(111), Si(100) and graphene. The ability of AES, as compared to more local probes, to follow the process in a dynamical way, allows us to study the growth of C60 below and over one ML, including the change of C60 growing over either Si or Cu to the growth over a C60 film. In the same way, we can follow the C60 desorption by heating the sample and under ion (He and Ar) bombardment.

    We found that the growth proceeds always as layer by layer. This result shows

    that differences in diffusion barriers are not as important as one can think following the idea of diffusion by a jumping mechanism. We propose that the sticking coefficient, governed by the adsorption energy, is the responsible of the differences observed between Cu and Si. Our results also point out to a different charge transfer among fullerene molecules and these surfaces.

    The sputtering experiments show, in a quite surprising way, that the erosion of

    C60 proceeds also in a LbL way. Although one is immediately tempted to think in a thermal process, through MD we found that it is determined by the back sputtering of substrate atoms.

  • 27O21 Signals of strong electronic correlation in

    ion scattering processes.

    F. Bonetto1,2 and E. C. Goldberg1,2

    1Instituto de Fsica del Litoral (CONICET-UNL), Gemes 3450, S3000GLN Santa Fe, Argentina. 2Departamento Ing. Materiales, Facultad de Ing. Qumica, Universidad Nacional del Litoral,

    Santiago del Estero 2829, S3000AOM Santa Fe, Argentina. Previous measurements of neutral atom fractions for Sr+ scattered by gold polycrystalline surfaces show a singular dependence with the target temperature. There is still no a theoretical model that can properly describe the magnitude and the temperature dependence of the neutralization probabilities found. Here we applied a first-principles quantum mechanical theoretical formalism to describe the time dependent scattering process. Three different electronic correlation approaches consistent with the system analyzed are used: i- Spinless approach, where two charge channels are considered (Sr0 and Sr+) and the spin degeneration is neglected, ii- infinite-U approach, with the same charge channels (Sr0 and Sr+) but considering the spin degeneration, and iii- finite-U approach, where the first ionization and second ionization energy levels are considered very but finitely separated. Neutral fractions magnitudes and temperature dependence are better described by the finite-U approach indicating that e-correlation plays a significant role on charge transfer processes. However, none of them are able to explain the non-monotonous temperature dependence experimentally obtained. Here, we suggest that small changes in the surface work function introduced by the target heating, and possibly not detected by experimental standard methods, could be responsible of that singular behavior. Additionally, we apply the same theoretical model using the infinite-U approximation to the Mg-Au system, obtaining an excellent description of the experimental neutral fractions measured.

  • 28O22 Estudio a 30 keV de procesos electrnicos en la

    colisin He++ + Ar

    A. Amaya-Tapia, A. Antilln y C. D. Estrada

    Instituto de Ciencias Fsicas, Universidad Nacional Autnoma de Mxico Se usa la aproximacin de parmetro de impacto para estudiar la colisin He++ + Ar a 30 keV y mediante el mtodo de Close Coupling se analizan secciones en la representacin de momentos. Se presentan los resultados de secciones parciales en canales de captura y diferenciales en energa de los electrones ionizados del canal transfer ionization. Se comparan con resultados experimentales y tericos disponibles en la literatura.

  • 29O23 Ion guiding through insulating capillaries: Survey

    of experiment and theory

    Nikolaus Stolterfoht

    Helmholtz-Zentrum Berlin fr Materialien und Energie, 14109 Berlin, Germany

    After the first observation [1] that keV ions are guided through insulating nano-capillaries, the topic has received considerable attention during the past decade. The essential property of the capillary guiding is a self-organizing process, which governs the charge deposition inside the capillaries [1,2]. With increasing deposition of the ions, the charge patch increases until the electrostatic field is large enough to deflect the ions. At equilibrium, the ions are guided maintaining their incident charge state. Developments of the field are summarized in accordance with a recent review over the field of capillary guiding [3]. Experiments are described giving emphasis to the guiding of highly charged ions in the keV energy range. Recent experiments with a single straight macrocapillary are presented allowing for the control of conductivity by changing the temperature of the material [4]. Single tapered capillaries are discussed involving an enhancement of the beam density and the production of a microbeam for biological applications. These studies have motivated several groups devoting efforts to the production of a beam with diameter of the submicron scale.

    Figure 1: Calculations of 4.5-keV Ar7+ ions incident at 0 and 1 into a conical capillary [5]. Apart from the experimental studies, theoretical concepts of the capillary guiding are discussed. Figure 1 shows results of calculations using a drift model for trajectories and charge distributions for 4.5-keV Ar7+ incident under 0 and 1 into a conical microcapillary [5]. The simulations show that the density of the transmitted ions is enhanced by a factor as large as 4. In particular, the theoretical results confirm unexpected experimental obser-vations of a minimum in the emission profiles at zero observation angle. Altogether, it is elucidated that capillary guiding involves several novel phenomena whose understanding has made essential progress. References [1] N. Stolterfoht et al., Phys. Rev. Lett. 88, 133201 (2002). [2] K. Schiessl et al., Phys. Rev. A 72, 062902 (2005) [3] N. Stolterfoht and Y. Yamazaki, Physics Reports 629, 1-107 (2016) [4] Gruber et al. Nucl. Instr. Methods B 314, 1 (2014), [5] N. Stolterfoht et al. Phys. Rev. A 91, 32709 (2015) Acknowledgement I am indebted to Yasunori Yamazaki for his collaboration in reviewing the field of capillary guiding

  • 30O24 Fukushima: Passado, Presente e Futuro

    Johnny Ferraz Dias Laboratrio de Implantao Inica, Instituto de Fsica

    Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves 9500, CP 15051, CEP 91501-970, Porto Alegre, RS, Brasil

    Em 11 de maro de 2011 um terremoto de magnitude 9 na escala Richter, seguido de um tsunami, atingiu a provncia de Fukushima, na regio de Tohoku, localizada no leste do Japo. Tais eventos causaram o desastre nuclear mundialmente conhecido como o acidente de Fukushima. Desde ento, o Japo adotou uma srie de medidas para a remediao e recuperao de reas afetadas pelo desastre nuclear. Nesta palestra sero discutidos conceitos bsicos de fsica atmica e nuclear relacionados com o acidente, incluindo os princpios de funcionamento dos reatores de Fukushima Daichii e a tcnica PIXE utilizada amplamente na anlise dos materiais radioativos oriundos do acidente nuclear. Iremos discutir tambm os eventos que levaram ao derretimento do ncleo do reator e suas consequncias. Alm disso, sero discutidos as medidas adotadas pelos japoneses para a remediao dos problemas causados pela contaminao radioativa de solos, gua e alimentos em geral. Finalmente, discutiremos o futuro da utilizao da energia nuclear, destacando seus benefcios e riscos. Agradecimentos. Agradeo CAPES atravs do Edital MEXCUBA e ao Prof. Keizo Ishii (Universidade de Tohoku Sendai) pela infraestrutura fornecida durante as viagens regio de Fukushima.

  • 31O25 On the radiolytic efficiency of high-energy ions

    confined in ultrathin polymer films

    R. M. Papalo

    Faculdade de Fsica, Pontifcia Universidade Catlica do Rio Grande do Sul,Av. Ipiranga 6681, Porto Alegre, Brazil

    In this talk, Ill briefly review recent results in our group on ion irradiation of polymer thin and ultrathin films, used as a model system to investigate confinement effects of ion tracks in one dimension. We followed the changes in radiation effects as the thickness is systematically reduced (from ~ 200 nm down to ~2nm) to investigate if the damaging capacity of fast ions is altered upon spatial confinement and at what critical length. Two types of experiments were conducted for ions in an energy range from 2 MeV up to 2 GeV: one involving surface effects, such as cratering and mass transport in single ion impacts; and another based on average effects of high-fluence irradiations to get information on the bond-breaking cross sections (i.e.,radiolytic efficiency). Ill focus on the chemical effects, which were mainly evaluated by X-ray photoelectron spectroscopy in PMMA and PVC films. Bond breaking cross sections of C-O and C-Cl bonds, were found to be to a large extent insensitive to thickness reductions, even in layers as thin as 5nm for both 2.2 GeV Bi and 2 MeV H irradiations. These findings indicate that most of the bond-breaking induced by the ions is related to short-range events close to the track core. Films thinner than ~5 nm were difficult to analyse, because of the non-negligible influence of the adventitious carbon on the substrate, combined to changes caused by the ion beam (such as roughening and thinning). Our observations are in contrast to our recent studies on surface effects, such as mass transport and cratering formation, which are substantially weakened, when individual ion tracks are confined into polymeric ultra-thin films, due to the suppression of cooperative effects of excited atoms along the ion track [1]. We will also show results on radial dose profiles due to the delta rays in thin water layers obtained from Monte Carlo simulations with the GEANT-DNA toolkit. Such simulations provide a first approach to rationalize the impact of film thickness on the energy spread by the secondary electrons, and allow the calculation of expected values for the damage cross sections for the different film thickness. [1] R. M. Papalo, R. Thomaz, L. I. Gutierres, V. M. de Menezes, D. Severin, C. Trautmann, D. Tramontina, E. M. Bringa, and P. L. Grande, Phys. Rev. Lett. 114, 118302 (2015).

  • 32O26 Nanoestructuras de carbono irradiadas por

    protones

    B. Fierro1 ,2 , J.D. Uribe1 , M. Mery1 , A. Corts , C. Celedn , J.E. Valds1 ,2

    1Depto. de Fsica, Universidad Tcnica Federico Santa Mara (UTFSM), Valparaso 2Centro para el Desarrollo de la Nanociencia y la Nanotecnologa (CEDENNA), Santiago Chile

    Correo electrnico: [email protected] Pese a lo vertiginoso del avance cientfico, y ya pasada una dcada desde su aparicin, el grafeno [1] contina siendo un campo activo y fructfero de la investigacin bsica [2]. Por otro lado, desde el punto de vista de sus aplicaciones, el carbono amorfo tipo diamante es un excelente candidato para usarse en nano- tribologa y biofsica [3]. En virtud de sus caractersticas, estos dos altropos del carbono nos han motivado para medir la prdida de energa de iones livianos de baja velocidad que inciden sobre tales materiales. En el presente estudio, mediante geometra de transmisin se investiga el poder de frenado de una monocapa de grafeno (0,35 nm de espesor) y de pelculas de carbono tipo diamante (entre 5 y 21 nm de espesor nominal) irradiadas por protones. Una variacin sistemtica de las condiciones de trabajo (presin en la cmara de colisiones, temperatura y tiempo de calentado de las muestras en vaco, dosis de bombardeo, entre otras), sumadas a la caracterizacin con microscopa Raman, nos revelan la presencia de contaminantes en grafeno. Seran estos ltimos, segn nuestras conclusiones, los que han inducido a reportar en la literatura valores extremadamente altos de frenado de iones que atraviesan pelculas ultra delgadas [4]. Adems, mediciones preliminares en carbono amorfo tipo diamante nos indican que su poder de frenado est muy por debajo de lo reportado para carbono amorfo. Referencias [1] Novoselov, Geim, et. al, Science. 306 (5696): 666669 (2004) [2] Bandurin et al., Science 10.1126/science.aad0201 (2016) [3] A. Tomala, A. Pauschitz and Manish Roy, Surface Science 616, 6070, (2013) [4] F. Allegrini et. al., Opt. Eng. 53(2), 024101 (2014) Agradecimientos Se agradece a los proyectos Basal CEDENNA FB0807 y UTFSM DGIIP 216.11.3 ao 2016, y a la Direccin General de Investigacin, Innovacin y Posgrado de la UTFSM.

  • 33O27 Sobre la difraccin cuntica que ocurre en

    colisiones rasantes de tomos neutros sobre aisladores

    J. E. Miraglia1 y M. S, Gravielle1,

    1Instituto de Astronoma y Fsica del Espacio, CONICET-UBA, Buenos Aires, Argentina

    Se estudia el proceso denominado fast atom diffraction (FAD) en la que tomos que inciden en forma rasante sobre superficies de LiF (aisladoras en general) son dispersados cunticamente presentando patrones de interferencias caractersticos (ver figura). La sensibilidad de dicho patrn es tal que exige un adecuado tratamiento de todos los aspectos que intervienen, que son variados y provenientes de diversas reas de la Fsica. Nos concentraremos slo en tres segmentos. La descripcin del proyectil debe plantearse con un tratamiento puramente ondulatorio. Lo importante al llegar al umbral del cristal aislador, es el conocimiento de la longitud de coherencia, trmino que debemos importar de la ptica Esta longitud debe ser atribuida al efecto descripto por el teorema de van Cittered Zernike. Para su determinacin se debe tener en cuenta las dimensiones del orificio de salida de la fuente, como as tambin la del colimador (el fenmeno equivalente al de Fraunhofer). Tambin hemos investigado el efecto de dos colimadores (el equivalente a la experiencia de Young).

    Los resultados son notables, ya que variando estos parmetros uno puede observar experimentalmente las interferencias de Bragg (extracelda) y los picos supernumerarios (intracelda), que pueden explicarse cualitativamente usando el principio de incerteza Desde el umbral frente al aislador comienza otro fenmeno que es la dispersin puramente cuntica del paquete de onda del proyectil cuyas dimensiones iniciales fueron determinadas va van Cittered Zernike. La dispersin de este paquete debido a la interaccin con el cristal debe hacerse via, por ejemplo

    Feyman path integral. En particular aplicamos una tcnica aproximada desarrollada por Miller que denominamos Surface initial value representation (SIVR). Este mtodo no entra en la categora de semiclsicos, como lo es la aproximacin eikonal, sino en la de semicunticos. Por ltimo nos queda describir la interaccin entre el proyectil y el cristal. Ya que el proyectil impacta en forma rasante (baja energa transversal) rebota a 3-4 a.u. sobre la superficie. En esa zona los fenmenos de intercambio y correlacin son importantes. Debemos recurrir a herramientas de la Qumica cuntica: en particular hemos usado el potencial ms popular del rea: B3LYP tomado a partir de la interaccin de a pares (pairwise). Se presentarn una comparacin con los resultados experimentales. [1] M.S. Gravielle y J.E. Miraglia, Phys. Rev. A 92 062709 (2015). Ver referencias all.

  • 34O28 Stopping power, estado del tema, tendencias

    e intereses

    Claudia Montanari

    Instituto de Astronoma y Fsica del Espacio, CONICET- UBA, Buenos Aires, Argentina Se presentar un anlisis del estado del tema de prdida de energa de iones en la materia (stopping power), su evolucin en los ltimos 15 aos y las nuevas tendencias en materiales de inters, incluyendo polmeros, xidos, y algunos materiales biolgicos. El trabajo toma en cuenta la administracin de la base de datos de stopping de Helmut Paul [1], actualmente incorporada a la International Atomic Energy Agency (IAEA) [2]. La base fue creada por Paul en 1990 y ha sido muy utilizada por la comunidad cientfica desde entonces. Incluye los valores experimentales desde las primeras mediciones en la dcada de 1930 hasta el presente, siendo actualizada en forma continua.

    El objetivo es presentar tanto tendencias como reas de vacancia tericas y experimentales para distintos materiales y rangos de energas. Mostraremos por ejemplo que en los ltimos 5 aos, del total de mediciones de stopping, un tercio corresponde a blancos atmicos y dos tercios a blancos moleculares, y entre ellos la mitad son xidos de inters tecnolgico [3]. Tambin que el blanco ms medido actualmente por distintos laboratorios es el Nitrato de Silicio, debido sto a su utilizacin en la industria pesada, motores, turbocompresores y partes para la industria automotriz y espacial. Sin embargo los valores experimentales de Si3N4 no son descriptos por las predicciones del cdigo SRIM, por ejemplo [4]. Referencias [1] H Paul, Nucl. Instrum. Meth. Phys. Res. B 268 (2010) 3421; AIP Conf. Proc. 1525 (2013) 295. [2] Stopping Power of Matter for Ions https://www-nds.iaea.org/stopping/. [3] R C Fadanelli et al, Eur. Phys. J. D 70 (2016) 178. [4] N Barradas et al, . Instrum. Meth. Phys. Res. B 360 (2015) 90.

  • 35O29 On the use of models of quantum confinement to

    study ion stopping in condensed matter.

    Salvador A. Cruz

    Departamento de Fsica, Universidad Autnoma Metropolitana-Iztapalapa, Apdo. Postal 55-534, 09340, Mexico City, Mexico

    An overview of the use of models of quantum confinement to account for differences in the stopping function between gas-phase and condensed-phase target materials is presented. The source of these differences stems on changes in the electronic structure of an atom/molecule embedded in a given material due to spatial limitation imposed by its neighboring constituents. An account of confinement models is presented to estimate physical-phase state effects in proton stopping and differences in mean excitation energies between surface and bulk atoms leading to corresponding differences in projectile energy-loss rates.

  • 36O30 Algoritmos de superresolucin aplicados a estudios

    de interaccin de plasmas con laseres

    A.M.Jurez1, L.M Hoyos-Campo1 y A. Capella-Kort2

    1Instituto de Ciencias Fsicas, Universidad Nacional Autnoma de Mxico, Ap. Postal 43-8, Cuernavaca, 62251 Morelos,

    Mxico 2Instituto de Matemticas, rea de la Investigacin Cientfica

    Circuito Exterior, Ciudad Universitaria Coyoacn, 04510. Mxico, D. F.

    En esta contribucin se presentan los principios y el uso de algoritmos de Super Resolucin spectral. Estos algoritmos se basan en la minimizacin de la norma L1 de el espectro, abstrado como un vector. Esta tcnica, que es un caso especfico del rea conocida como Sensado Comprimido (Compressed Sensing) se aplica en este trabajo a datos experimentales de interaccin de laseres con plasmas. Estos datos presentan originalmente resolucin espectral modesta. El algoritmo de resolucin permite mejorar la resolucin espectral y resolver estructuras reales que en los datos originales no eran separables. Este tipo de efectos, que pueden parecer contraintuitivos, se han obtenido previamente en procesamiento de imgenes y sta es la primera vez que se aplica a espectros. Se discutirn los lmites de esta poderosa herramienta matemtica, en particular el efecto del ruido, y la necesidad de hacer un correcto modelaje matemtico del experimento. Referencias EPL (Europhysics Letters), Volume 113, Number 4, L. M. Hoyos-Campo, A. M. Juarez and A. Capella.

  • 37O31 Espectroscopia lser sin ensanchamiento Doppler

    de las transiciones prohibidas por la aproximacin dipolar elctrica 5P3/2 -> 6Pj (j = 3/2, 1/2) en tomos trmicos de

    rubidio.

    F. Ponciano-Ojeda,1 S. Hernndez-Gmez,1 O. Lpez-Hernndez,1 C. Mojica-Casique,1 R. Coln-Rodrguez,1 L. Hoyos,1 J. Flores-Mijangos,1 F. Ramrez-

    Martnez,1 D. Sahagn,2 R. Juregui,2 y J. Jimnez-Mier.1

    1Instituto de Ciencias Nucleares, Universidad Nacional Autnoma de Mxico, Ciudad de Mxico, 04510, Mxico

    2Instituto de Fsica, Universidad Nacional Autnoma de Mxico, Ciudad de Mxico, 04510, Mxico

    La aproximacin dipolar elctrica es la base para el estudio de la interaccin entre la radiacin electromagntica y los tomos. Es natural investigar esa interaccin ms all de la aproximacin dipolar elctrica. En este trabajo se presentan resultados de espectroscopia lser de las transiciones prohibidas 5P3/2 -> 6Pj (j=1/2, 3/2) en rubidio atmico. Los experimentos se hicieron en celdas de absorcin a temperatura ambiente y con lseres con anchos de banda de unos cuantos megaHertz. tomos en el estado inicial de la transicin (5P3/2) se producen por excitacin con un lser de preparacin de diodo con cavidad externa. La produccin de tomos en el estado 6Pj es monitoreada por su decaimiento directo al estado base (5S) mediante la emisin de luz azul a 420 nm. Cuando los dos lseres se contrapropagan en el medio atmico se obtienen espectros de fluorescencia con resolucin de la estructura hiperfina del estado 6Pj, con anchos de lnea significativamente menor que el ancho Doppler. Los resultados se comparan con clculos realizados en un modelo de tres pasos (preparacin dipolar elctrica excitacin cuadrupolar elctrica decaimiento dipolar elctrico) que incluye efectos de seleccin de velocidades, bombeo hiperfino y polarizacin de la luz en el paso de preparacin, y efectos de polarizacin del haz que produce la transicin prohibida. Se encuentra un muy buen acuerdo entre experimento y teora cuando se supone que la transicin prohibida es cuadrupolar elctrica. Teora y experimento muestran que los espectros son muy sensibles a los estados de polarizacin de los haces de preparacin y cuadrupolar elctrico, y que es posible aislar reglas de seleccin cuadrupolares elctricas DMF especficas seleccionando la polarizacin de los dos haces. Agradecimientos Agradecemos el apoyo de J. Rangel para la fabricacin de los lseres de diodo. Este trabajo fue apoyado por DGAPA-UNAM, Mxico, mediante los proyectos PAPIIT IN116309, IN110812, IA101012 e IN112516, y por CONACyT, Mxico, mediante el proyecto de Ciencia Bsica No. 44986 y el proyecto Laboratorio Nacional LN260704.

  • 38

    Posters:

    P1 Time-of-Flight Secondary Ion Mass Spectrometry beamline at the Ion Implantation Laboratory: Current status

    and perspectives

    I. Alencara,, L. A. B. Niekraszewicz a, P. L. Grandea, L. Amarala, J. F. Diasa, R. M. Papalob,W. Wolffc

    aInstituto de Fsica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves 9500,

    91501-970 Porto Alegre, Brazil bDepartamento de Fsica, Pontifcia Universidade Catlica do Rio Grande do Sul, Av. Ipiranga

    6681, 90619-900 Porto Alegre, Brazil cInstituto de Fsica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos 149,

    21941-909 Rio de Janeiro, Brazil A mass spectrometer was installed at a new beamline of the 3 MV Tandetron accelerator in order to investigate the secondary ion emission of target solids employing MeV ion sources. The instrument was purchase from Kore Technologies Ltd. and it includes a high voltage pulsed stage, an asymmetric electrostatic lens, a reflectron, and a micro-channel plate detector. The system operates in cycles ( 100 s) triggered at the extraction pulse using a time-to-digital converter, which measures the time-of-flight of secondary ions in a field-free flight tube. The great advantage on the use of MeV primary ions is the yield (number of secondary ions emitted per incident primary ion) enhancement and the lower fragmentation of molecules. Such systems open several possibilities and, in this work, a few examples are illustrated. As the underlying physics after the emission of secondary ions is relatively simple, knowledge of the applied fields and distances allows the simulation of the flight intervals. In this way, the initial velocity distribution can be computed and they were investigated for organic (PMMA, leucine) films. A particularity of our system is the use of continuous beams, which can be applied for the in situ study of surface modification. Results for LiF crystals shows that the emission of Li+ increases with ion dose when neutralization is employed. Another application focuses on the degradation of chemotherapeutic molecules during ex situ treatments. This work was financially supported by Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES).

  • 39P2 Compositional depth profile investigation of plasma

    doped Si/SiO2:As by Medium-Energy Ion Scattering

    I. Alencara,*, G. G. Marmitta, P. L. Grandea, J.G. Englandb, A.K. Rossallc, J.A. van den Bergc

    aInstituto de Fsica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves 9500,

    91501-970 Porto Alegre, Brazil bVarian Semiconductor Equipment, Silicon Systems Group, Applied Materials Inc, 35 Dory Road,

    MA 01930 Gloucester , USA cInternational Institute for Accelerator Applications, School of Computing and Engineering,

    University of Huddersfield, 6 Queensgate, HD1 3DH Huddersfield , UK In this work, the capability of Medium-Energy Ion Scattering (MEIS) to describe nano-structured composites is illustrated. For this purpose, the plasma doping (PLAD) technique for implanting As into Si wafers with a native SiO2 layer is investigated by MEIS after the samples had been submitted to wet cleaning and thermal treatment processes. Through the analyses of scattering by single and cluster ion beams with the same specific energy and charge state, the Coulomb explosion allows the compositional determination as a function of depth by modeling the target structure with the PowerMEIS code. The results are compared to independent measurements made by Transmission Electron Microscopy with Energy Dispersive x-ray Spectroscopy (TEM-EDS). This work was financially supported by Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES).

  • 40

    P3 Valine decomposition by H+, He+ and N+ MeV ions

    C. A. P. da Costa1 and E. F. da Silveira1

    1 Departamento de Fsica, PUC-Rio, Rua Marqus de So Vicente 225, 22451-900, Rio de Janeiro, Brazil

    Valine (Fig. 1) is an amino acid that has been o