Graduate and Research Central Coordination Office (CCPG)

Study of the Molecules Fragmentation in Collisions with Heavy Ions

Researcher: Geraldo Monteiro Sigaud

A quantitative description of many-body systems time-dependent, i.e., what is the time evolution of a system of mutually interacting particles is one of the most fundamental questions of physics still unresolved. In Atomic and Molecular Physics, due to the nature of long-range Coulomb potential is extremely difficult to find suitable numerical methods for a wide range of speeds and collision systems. The study of multi-electron processes, comprising single or multiple ionization of the projectile and target capture and electronics, among others, in collisions between ions and atomic and molecular targets, and their influence on molecular fragmentation process, has grown tremendously in recent years, mainly because such processes have a very important role in Plasma Physics, Astrophysics, Atmospheric Physics, Materials Physics in Medicine and Biology.

In this context, we have experimentally studied the interaction between ions and molecules with few heavy atoms, especially potentially precursor molecules of biological structures, such as H2O, CH4, NH3, N2, O2, NO, HCN, etc.. At speeds intermediate regime. These studies aim to clarify the molecular fragmentation occurs sequentially or "explosive", and that the dominance of these mechanisms with respect to the speed and type of projectile. Such information is of fundamental importance, for example in the radiotherapy of tumors with heavy ions, so that you can determine which beam should be used with greater efficiency in the destruction of cancer cells with less damage to healthy cells. A key issue for this choice is related to the reactivity of the fragments produced to the water molecule, which determines its ultimate effect on the irradiated tissues. Besides this, another application is related to the interaction of energetic particles from the solar wind with existing molecules in planetary atmospheres and surfaces of planets and comets in our solar system, to provide very important information for understanding phenomena related to its evolution in time, for example, the formation water and the planetary atmospheres current. These activities are developed in the Laboratory of the Van de Graaff accelerator.

Line of Research 1: Molecular Biophysics

Researcher: Sonia Renaux Wanderley Louro

The Center for Molecular Biophysics Research consists in detecting sites of interaction of various signaling molecules with drugs and biomolecules; characterize these sites from the standpoint of structural and kinetic; investigate conditions that modulate interactions, correlating structure and kinetics with functional effects. We have obtained results on the elucidation of the molecular mechanisms of interaction of drugs with their targets in subcellular systems: biomembranes, soluble proteins and model systems. The potential use of nanoparticles for protein transport and controlled release of drugs from a living is great. Due to the small size and high magnetization, magnetic nanoparticles can be used to monitor and influence cellular processes. Various synthesis methods of magnetic particles have been developed, but detection, encapsulation and functionalization of those particles by biologically active molecules has been a challenge. Looking encapsulating magnetic particles with proteins and biomembranes in order to control connection and release of drugs. These activities are developed in the. Laboratory of Spectroscopy of Biomolecules.

Line of Research 2: Magnetic Nondestructive Testing

Researcher: Antonio Carlos Oliveira Bruno

Magnetic Nondestructive Testing are the development and application of methods and techniques for analysis of magnetic components or structures, so as not to alter its characteristics or impair its future use. Its goal is to analyze the integrity, composition and properties and also detect, locate and evaluate discontinuities, defects or other imperfections. Its use is of great importance in industry, accident prevention and environmental preservation. The Laboratory of Magnetic Nondestructive Testing uses high resolution magnetometer (SQUID, Fluxgate, GMI, GMR) for this purpose in many cases where it is possible the solution of Inverse Problem is that getting the geometry of the imperfection or defect. In industry, the assays are used since the stages of manufacture of the material until the monitoring systems already in use, for example, to determine critical regions for structures, components and devices used in the aviation industry, nuclear, chemical processing and petroleum industry. As these structures are subject to phenomena such as fatigue, stress corrosion and the appearance of defects such as cracks is very likely. These cracks can grow to cause impairment of the component or structure with disastrous effects to safety and the environment.

Line of Research 3: Stochastic dynamics

Researcher: Celia Anteneodo

Besides the dominant contributions to describe the dynamics of a system, there are components, typically associated to a great number of degrees of freedom involved, which cannot be defined in a deterministic way, even outside the quantum mechanics field.

However, the classical dynamics can be modeled incorporating the motion deterministic equations of an appropriate floating force (stochastic). Thus, an equation of the Langevin type is obtained, as the modeling of the Brownian movement of the dust in the air corpuscles.

An Alternative treatment is the dynamics probabilistic description, through an equation for the density of the system state probability (such as the Fokker-Planck equation).

These stochastic representations allow modeling many systems, not only physical, and some of the applications I have been working:

• Bownian motors
• Extensive dynamical systems
• Time series of prices and other interest variables in finance

Publications

• Econophysics
  • Additive-multiplicative stochastic models of financial mean-reverting processes C Anteneodo & R Riera, Phys Rev E 72, 026106 (2005)
  • Nonextensive statistical mechanics and economics C Tsallis, C Anteneodo, L Borland & R Osorio, Physica A 324, 89 (2003)
  • Risk aversion in economic transactions C Anteneodo, C Tsallis & AS Martinez, Europhys Lett 59, 635 (2002)
• Anomalous diffusion
  • Brownian motors in nonlinear diffusive media C Anteneodo, Phys Rev E (2007), in press
  • Diffusive anomalies in a long-range Hamiltonian system LG Moyano & C Anteneodo, Phys Rev E 74, 021118 (2006)
  • Long-time behavior of spreading solutions of Schrodinger and diffusion equations C Anteneodo, JC Dias & RS Mendes, Phys Rev E 73, 051105 (2006)
  • Non-extensive random walks C Anteneodo, Physica A 358, 289 (2005)
  • Escape time in anomalous diffusive media, EK Lenzi, C Anteneodo & L Borland, Phys Rev E 63, 051109 (2001)
• Other applications
  • Sinchronization threshold in coupled logistic map lattices C Anteneodo, AM Batista & RL Viana, Physica D 223, 270 (2006)
  • Multiplicative noise: A mechanism leading to nonextensive statistical mechanics C Anteneodo & C Tsallis, J Math Phys 44, 5194 (2003)
  • Theoretical estimates for the largest Lyapunov exponent of many-particle systems RO Vallejos & C Anteneodo, Phys Rev E 66, 021110 (2002)
  • Maximum entropy approach to stretched exponential probability distributions C Anteneodo & AR Plastino, J Phys A 32, 1089 (1999)
  • A dynamical thermostatting approach to non-extensive canonical ensembles AR Plastino & C Anteneodo, Ann Phys 255, 250 (1997)
  • Apostila "Processos estocásticos", V Escola do CBPF: http://www.cbpf.br/~celia/pg2new.pdf

Line of Research 4: Organic electrominescent devices (OLEDs)

Researcher: Marco Cremona

The organic light emitting devices, known as OLEDs, are constructed from various types of organic molecules and form electroluminescent materials. Technology is rapidly evolving and it could represent a strong competitor to consolidated liquid crystal screens. Among the advantages of the use of OLEDs for building flat panels are low cost, ease of application of the device, and its characteristics: adapt the flexible material (as, for instance, a folding screen, goggles and helmets virtual ); enable constructions of any size screens; natural light emitters are providing superior brightness and color. The interest in organic materials occurs mainly because display optical and electrical properties modifiable viewpoint molecular and / or atomic (nanostructured materials and functionalization of organic compounds). Ie: research in OLEDs is a nanoscience research with applications in nanotechnology. The macroscopic device made from organic compounds show properties that reflect those "nano" and therefore will be a nanotechnological device. OLEDs promise to be economical light sources, low weight and that can potentially be made in any size and on a large number of substrates (including also the flexible plastic).

This activity is developed in the Thin Films Laboratory and the optics Spectroscopy and optoelectronics Molecular Laboratory.

Line of Research 5: Magnetic Nondestructive Testing

Researcher: Antonio Carlos Oliveira Bruno

Magnetic Nondestructive Testing are the development and application of methods and techniques for analysis of magnetic components or structures, so as not to alter its characteristics or impair its future use. Its goal is to analyze the integrity, composition and properties and also detect, locate and evaluate discontinuities, defects or other imperfections. Its use is of great importance in industry, accident prevention and environmental preservation. The Laboratory of Magnetic Nondestructive Testing uses high resolution magnetometer (SQUID, Fluxgate, GMI, GMR) for this purpose in many cases where it is possible the solution of Inverse Problem is that getting the geometry of the imperfection or defect. In industry, the assays are used since the stages of manufacture of the material until the monitoring systems already in use, for example, to determine critical regions for structures, components and devices used in the aviation industry, nuclear, chemical processing and petroleum industry. As these structures are subject to phenomena such as fatigue, stress corrosion and the appearance of defects such as cracks is very likely. These cracks can grow to cause impairment of the component or structure with disastrous effects to safety and the environment.

Line of Research 6: Physical and Surface Analysis

Researcher: Enio Frota da Silveira

The Group investigates the interactions of ionizing radiation with solid surface. Attention is focused radiation beams consisting of:

1. Fast particles (atoms, molecules or ions with energy of 0.1 MeV to 100);
2. In the ultraviolet photons (synchrotron light or laser).

The samples are typically inorganic insulating materials (salts, oxides and gas condensates) and organic (polymer, biomolecule). The observation of the effects of the interaction is performed mainly by spectrometry by time-of-flight (TOF) of the ions emitted by the solid during irradiation. A characteristic of this type of interaction is the desorption of large ionic molecular aggregates or macromolecules intact. Chemical and physical changes are analyzed: new compounds are produced and identified changes in crystallographic and topological properties are modeled, erosion rates are measured by electronic sputtering.

The particle beams are produced by the Particle Accelerator Van de Graaff at PUC-Rio and radioactive sources of californium 252 of the Laboratory of Mass Spectrometry Macromolecules; the synchrotron light are obtained at LNLS. The activities are theoretical (model development desorption ion and modeling of molecular structures), experimental (obtaining basic data) and instrumental (design and development of specific equipment).

Applications: materials science and nanotechnology (eg production and characterization of clusters), astrophysics (eg formation of prebiotic molecules). MALDI and LDI techniques are employed for the identification and characterization of proteins in the area of functional genomics and proteomics, and the analysis of synthetic polymers, enzymes and other products of biotechnological interest.

Line of Research 7: Econophysics - Statistical Physics applied Applied to Financial Markets

Researcher: Rosane Rieira Freire

Statistical methods developed for the study of physical systems are used in the description of complex dynamic fluctuations financial time series. The analogy with natural phenomena such as diffusion, phase transition, turbulence, etc.., Opens a range of new analytical techniques and / or numeric for the description of economic phenomena. We analyze the following issues:

1. Financial market dynamics: temporal evolution of the distribution of price returns, volatility etc and their properties by scaling temporal analysis of daily and intraday behavior.
2. Analysis of fluctuations in financial variables using generalized stochastic equations governed by Ito-Langevin and Fokker-Planck.
3. microscopic models: analysis of price formation by simulating the market as a system of heterogeneous agents connected via a data network.
4. Financial Crash: description of cooperative behavior emerging in the market in times of crisis in analogy with critical phenomena.

Line of Research 8: Statistical Physics of Non-Equilibrium and Granular Systems

Researcher: Welles Antonio Martinez Morgado

The study of non-equilibrium systems is an area that has been developing rapidly in recent decades due to the development of electronic computing can simulate problems inaccessible to analytical approaches. This area deals with problems ranging from the Brownian motion of particles to granular systems. The latter are special object of my search. The understanding of these systems enables us to obtain a window (experimental numerical and analytical) about the behavior of real dissipative systems as well as contributes to the development of technological applications of industrial importance such as grain transport, storage and mixing.

Line of Research 9: Magnetism Applied to Art

Researcher: Paulo Costa Ribeiro

We obtain the magnetic images of oil painting, acrylic painting, sacred sculptures, ceramics and cave paintings. A new technique is been developed for the authenticity of art works and dating of ceramic and cave art paintings. It has been discovered that the some of the pigments from the painting are magnetic and the magnetization can be detected by sensors like the SQUID and FLUXGATE using an x-y scanner. These inorganic pigments have transition metals that may be magnetic. They can be ferromagnetic and we could orient them in an external magnetic field. It is possible a magnetic scan paintings and use them to identify forgeries and also to make dating of the cave art paints.

Line of Research 10: Nanolithography by Atomic Force Microscopy and Scanning Tunneling

Researcher: Rodrigo Prioli Menezes

Despite considerable interest in nanoscopic systems, their controlled fabrication, characterization, understanding represents a huge challenge for the scientific and technological community. In the Laboratory of nanoscopy associated with Van de Graaff Laboratory we apply the techniques of scanning tunneling microscopy (STM) and atomic force (AFM) for surface characterization at the atomic scale. These microscopy techniques allow visualization of areas with high resolution and chemical modifications or structural materials are carried out in a controlled manner. The goals are to use the force between atoms measured by atomic force microscope to induce structural changes in surfaces. Moreover, we also use the current tunneling microscope as an electron beam to induce breakage and formation of chemical bonds on surfaces with high spatial resolution. These changes induced by AFM or STM allows us to understand basic physical processes related to energy dissipation at surfaces and allow new electronic or optical devices can be fabricated in nano-scale

Line of Research 11: Carbon Nanotubes

Researcher: Fernando Lázaro Freire Jr

It is well known that carbon nanotubes have exceptional properties. Beside the many proposed applications, its use as a gas sensor occupies a prominent role. Impurities adsorbed or embedded in the wall of a carbon nanotube can significantly alter its electrical conductance. Carbon nanotubes can also be doped with catalysts that interact with gas molecules providing specific and rapid detection of these very efficient. Moreover, by placing in appropriate matrices nanotube, it is expected that the resulting composite has properties, mechanical, thermal or electrical improved when compared with the original array. Our interest is in systems involving metals, a topic that has only recently attracted the attention of researchers. In the case of incorporation of nanotubes in the metal matrix can expect improvement of mechanical properties, increased hardness and resistance to fatigue and wear, but positive results are also expected with regard to electrical and magnetic properties. In the Laboratory of Protective Coatings are grown multi-walled nanotubes by spray pyrolysis techniques and plasma CVD, as well as prepared simple devices (sensors).

Line of Research 12: Molecular Optoelectronic and Optical Spectroscopy

Researcher: Marco Cremona

The Molecular Electronics (EM), which is part of the new scientific view of Nanoscience and Nanotechnology, is shaping up as one of the strategic areas for technological development of many countries, an international market of several billion dollars. The ongoing quest for miniaturization of devices has forced scientists to look for new forms of electronics where certain molecules with specific functions replace the silicon components present in the current circuits. The molecular transistors and organic LEDs are two examples of how AT can reach fabricate macroscopic objects from the manipulation of atoms and molecules (bottom-up view). Our group is one of the few in Brazil studying these types of devices based on thin films of conjugated organic molecular complexes. Using techniques of optical spectroscopy and electrical and through our collaborations with research groups nationally and internationally, with several important results can organic materials, pure or doped with rare earths. In the Laboratory of Molecular Spectroscopy Optics and Optoelectronics and Laboratory of Thin Films in're equipped with a clean room for the production of thin films and we have systems of characterization of devices.

Line of Research 13: Electronic Properties of Materials

Researcher: Maria Matos

Atoms in solids can form from various spatial arrangements. Currently are synthesized in the laboratory a growing variety of new materials, many extremely attractive for research and application. Atomic arrangements can create ribbons of atoms between cross-, corrugated plans, open channels, these dense clusters and true microscopic structures influence the properties of the material, from its color to the ability to magnetize up, conduct electricity, resist heat, stay and accelerating chemical reactions, transformed with time or according to external conditions. The work in our group is theoretical. We studied the crystal structure of compounds from simple to complex, we calculate the energies involved in the process of conductivity, the ability to form vacancies in the optical absorption and atomic pair bond in order to understand the structural stability of the compound. Our approach takes into account the forming process of the structure imagining it through the junction of sub-structures (tapes, flat sub-units of different sizes and shapes), thereby increasing the understanding of the properties of the material. Mainly we are interested in the study of oxides structure and specific functionality, such as oxo-borate (warwickitas and ludwigitas) the perovskite copper and apatite, which are important for basic research, for the electronics industry and medicine. Examples of recent results of the group, has demonstrated the role of Ca in the formation of vacancies, which would explain the giant dielectric constant of a modified perovskite. In the study of oxo-borates has been shown that minor structural distortions caused by Fe atoms are able to radically change the electrical conductivity of a ludwigita, making it semi-conductive. We also show that small doses of vanadium can increase the uni-dimensional character of warwickita Fe, by shielding effect. We are currently investigating a series of compounds of the family of apatites, materials used for dental implant and proposed as catalysts in industry.

Line of Research 14: Electronic Properties and Transport in Nanoscopic Systems

Researcher: Maria Augusta and Enrique Vitoriano Anda

Advances in growth techniques of nano-structured semiconductor devices and the variety of their possible applications have motivated further study of the fundamental processes that control the electronic transport, in order to improve the properties of these devices. Will study the transport properties of systems such as quantum wires, nanoscopic rings and more complex structures consisting of clusters of PQ's connected to these systems. We will also transport molecule, creating entangled states within the quantum information, the Kondo effect and other properties related to the interactions of many-body present in these systems. It is sought an understanding of the properties of these systems as a function of time, temperature and values of system parameters, considering interactions local and non-local, direct and exchange to equilibrium systems and outside of thermodynamic equilibrium. The goal is to understand the fundamental physical processes associated with these systems and have powerful theoretical tools for the design of devices based on nanoscopic structures mentioned.

Line of Research 15: Nanostructured Coatings

Researcher: Fernando Lázaro Freire Jr, Marcelo E. Maia da Costa and Rodriog Prioli

Metallic nanostructures, ceramics and composite beside nanostructured materials based on carbon, may have mechanical, tribological and thermochemical unprecedented in the long history of development of various fields of technology of protective coatings to surfaces of materials. In the last decade nanostructured coatings begin to occupy a prominent place and nanohardness has constituted the first but not the only, property to be optimized. To achieve the desired high performance targets, we must also optimize at nanoscopic scale, tribological properties, physical and chemical. In our case, we studied the Laboratory Protective Coatings different types of nanostructured coatings, and multilayer coatings based on carbon, which may have one or more of the following characteristics: high hardness, low friction, wear resistance, hydrophobicity, and which is chemically inert. We have it for a wide range of characterization techniques nanoscopy installed in Laboratory of Van de Graaff accelerator, atomic force microscopy and scanning tunneling, nanoindentation, and XPS analysis techniques for ion beams (RBS, ERD and NRA).

Line of Research 16: Strongly Correlated Electronic Systems

Researcher: Hortencio Alves Borges

Strongly Correlated Electronic Systems include a broad range of materials which exhibit unusual and important properties. Among these, one finds High Temperature Superconductors, Heavy Fermions systems. In relation to the first, we study the interactions that lead to the occurrence of zero resistance phenomenon at near temperatures of liquid nitrogen, and the possibilities of technological devices applications built with these materials. In relation to Heavy Fermions, we are interested in unveiling the importance of magnetic interactions between rare–earth metal electrons that constitute them, for the occurrence of magnetic order, of superconductivity of an unconventional character and the transition between these states at extremely low temperatures, configuring quantum phase transitions. Finally, the possibility of connection between the phenomena of superconductivity in the two above groups of materials is also investigated. These activities are developed in the Materials under Extreme Conditions Laboratory.

Line of Research 1: Study of Cosmic radiation at extreme energies

Researcher: Ronald Cintra Shellard

The Earth is constantly bombarded by cosmic radiation, covering a very wide energy spectrum. The part of the upper bound of this spectrum, where the energies have values above 1018 eV is very little known. Besides being very rare, cosmic rays at these energies have a flow of the order of one particle per square kilometer per year, its origin and nature offers a view of the high-energy phenomena occurring in the universe. Understanding the origin and nature of these extreme energy rays is one of the biggest challenges of contemporary physics. Its study allows one to glimpse unexplored crannies of physics. To study these astroparticles, the Pierre Auger observatory in Argentina was built, and another one will be built in Colorado, U.S.A. The observatory, the world's biggest in its class, measures the characteristics of this radiation by using two complementary techniques. A set of telescopes measures the fluoresce of molecules in the atmosphere, generated by the passage of cosmic rays and the other measures the amount of radiation reaching the Earth by a selective sampling process. Our group develops algorithms for the reconstruction of information collected by the detectors, seeking to chisel the techniques in order to allow the identification of components of an atmospheric shower generated by a cosmic ray. We seek to identify potential sources of cosmic rays, which is equivalent to make astronomy of cosmic rays, to measure the flow of particles, identifying their nature, establishing mechanisms to explain its origin.

Line of Research 2: High Energy Physics

Researcher: Carla Gobel

The High Energy Physics is concerned with the study of the nature of elementary particles and their interactions. In the experimental field, the lines of inquiry being developed here are given through participation in international collaborations FOCUS (Fermilab, USA) and LHCb (CERN, Switzerland).

FOCUS (Fermilab, USA): Experiment focused on the study of particles containing the charm quark, which took data in 1996/1997. We are currently working on an analysis of hadronic decays of mesons D, interested in the study of production and interference of hadronic resonances with lifetimes of less than 10-20 seconds. In particular, we seek to study the production and characteristics of light scalar mesons issue, one of the major topics of current interest in hadron physics.

LHCb (CERN, Switzerland): The LHCb experiment is currently in assembly, one of four large experiments at CERN LHC collider, which will start operating in 2007-8, with energy of 14 TeV center of mass proton collisions -proton. The main goal of LHCb is studying the phenomenon of Rape Charge-Parity (CP) mechanism connected directly to the matter-antimatter asymmetry in the universe. At the current stage of preparation for the start of the data taking, LHCb in my project turns to the sensitivity study for the experiment that will measure the angle beta, one of the main parameters governing the CP violation in the Standard Model. This study is a "thermometer" to estimate the sensitivity of the LHCb several other parameters that characterize CP violation.

Line of Research 3: Neutrino Physics and Astrophysics 

Researcher: Hiroshi Nunokawa

Neutrino is a particle interaction has very weak and difficult to detect, but had very important role for the development of elementary particle physics. In the last decade, neutrino oscillations, which implies nonzero neutrino masses, were observed and confirmed by several experiments that detected neutrinos coming from the atmosphere, sun, accelerators and nuclear reactors. Although leave huge amounts of experimental data very important that allowed us to learn many things about neutrino, there are still several open questions (indeterminate properties of neutrinos) which may possibly provide some important clues to physics beyond the standard model of elementary particles. We are studying how and to what extent we can determine these properties of neutrinos that are not determined until the present time, such as CP violation (symmetry between matter and anti-matter), the hierarchy of neutrino masses (the mass of the third generating neutrino is greater than the first or otherwise), neutrinos are for particle Dirac or Majorana, etc.. We also study neutrinos coming from astrophysical sources such as a supernova explosion that created the neutron star or black hole, to understand physics of supernova.

Line of Research 1: Applied Optics in Biomedical Area 

Researcher: Isabel Carvalho

Stem cells are cells that have the ability to divide for indefinite periods long and can consist of an unlimited source of specialized cells in the adult. This line of research we investigated the induction of differentiation of stem cells by means of electrical stimuli, through various optical techniques. Devices based on optical fibers special microstructures are being developed for the assessment of the various stages of differentiation and spatial organization of adult stem cells during the evolutionary process of stem cells for myocardial cells. This research is performed in the Laboratory for Optoelectronics.

Line of Research 2: Non-linear optics in Vitreous Systems 

Researcher: Isabel Carvalho

You can write intense electric fields permanently in glasses and optical fibers through a process of electro-thermal polarization. One can thus obtain a material or highly nonlinear fiber that can potentially be used in frabricação components such as modulators, folders of different frequency and optical sensors. Various materials, whether in volume or special fibers are investigated such as silicate glass, special glass with high refraction index and the sol-gel films containing nano-particles of gold. Fundamental aspects of nonlinear process, as load distribution, role of doping and spatial distribution of the field are investigated with a view to implementing the systems in manufacturing photonic devices both in fibers and in volumetric samples. Device optical fiber-based liquid crystal are also studied. This research is performed in the Laboratory for Optoelectronics.