A5052371876- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Science and Education Research
- Nuclear Physics and Applications
- Atmospheric Ozone and Climate
- Chemistry Education and Research
- Education and Digital Technologies
- Laser-induced spectroscopy and plasma
- Spectroscopy and Laser Applications
- Education Pedagogy and Practices
- Radiation Therapy and Dosimetry
- Astrophysics and Star Formation Studies
- Spectroscopy and Quantum Chemical Studies
- Nuclear physics research studies
- Atmospheric chemistry and aerosols
- Science and Science Education
- Muon and positron interactions and applications
- Astro and Planetary Science
- Experimental and Theoretical Physics Studies
- Advanced Fiber Optic Sensors
- Radiation Shielding Materials Analysis
Universidade Federal do Rio de Janeiro
2015-2024
Universidade de Brasília
2018
Fundação Getulio Vargas
2018
Centro de Tecnologias Estratégicas do Nordeste
2018
Ministry of Finance
2018
Canadian Light Source (Canada)
2017
Universidade Estadual de Santa Cruz
2015
Secretaria Municipal de Saúde
2012
Pontifical Catholic University of Rio de Janeiro
1995-2009
Universidade do Sul de Santa Catarina
2006
Time-of-flight-based mass analysis of charged water fragments have been used to measure the dissociative and nondissociative reaction pathways formed during collisions with $15\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}100\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ $500\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}3500\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ ${\mathrm{H}}^{+}$ projectiles...
Probiotic foods are mainly restricted to dairy and soy products. This study aimed develop a new probiotic beads similar fish eggs, commonly used in oriental cuisine. Beads were produced by the extrusion encapsulation technique with calcium alginate, added one of following cultures: Lactobacillus rhamnosus GG ATCC 53103 Bifidobacterium animalis DN-173 010 stored for 30 days at 4 °C. The characterized size, weight, morphology viability strains different storage temperatures simulated gastric...
Absolute multiple-ionization cross sections, ${\ensuremath{\sigma}}^{q+},$ of He $(q=1,2),$ Ne $(q=1,2,$ and 3), Ar Kr Xe $(q=1,2,3,$ 4) atoms have been determined for interactions with ${\mathrm{He}}^{+}$ ions in the 1.0--3.5-MeV impact energy range. Special care was taken to obtain slow recoil-ion detection efficiencies, by measuring recoil coincidence ${\mathrm{C}}^{3+}$ capture channel comparing these results absolute single measurements. Comparison is made data available literature. The...
The dissociative photoionization of the chloroform and chloroform-d molecules has been studied in valence region around chlorine 2p edge. Time-of-flight mass spectrometry coincidence mode-namely, photoelectron-photoion (PEPICO)-was employed. He I lamp tunable synchrotron radiation were used as light sources. Total partial ion yields have recorded a function photon energy. Singly, doubly, triply ionized species observed below (195 eV), on (201 above (230 eV) Cl resonances. A definite degree...
Formic acid is much more abundant in the solid state, both interstellar ices and cometary ices, than gas (ice/gas ) this point remains a puzzle. The goal of work to experimentally study ionization photodissociation processes HCOOH (formic acid), glycine precursor molecule. measurements were taken at Brazilian Synchrotron Light Laboratory (LNLS), employing soft X-ray photons from toroidal grating monochromator TGM) beamline (200–310 eV). Mass spectra obtained using photoelectron photoion...
Cross sections for the processes of projectile electron loss and single double capture ${\mathrm{C}}^{3+}$ ${\mathrm{O}}^{5+}$ ions impinging on He, Ne, Ar, Kr, Xe targets were measured in energy range 1.0--3.5 MeV. The cross present a strong saturation as target atomic number increases, all systems collision channels studied. single-capture data are compared with calculations based semiclassical model eikonal approximation, both presenting good general agreement experiment. In case loss,...
Absolute, total, single- and multiple-electron-loss cross sections are measured for $1.4\text{\ensuremath{-}}\mathrm{MeV}∕\mathrm{u}\phantom{\rule{0.3em}{0ex}}{\mathrm{U}}^{4,6,10+}$ ions colliding with neon argon atoms nitrogen molecules. It is found that the all have same dependence on number of electrons lost multiplying by initial in $6s$, $6p$, $5f$ shells yields good agreement between different projectiles. By combining present data previous measurements made at velocity, it shown...
The methyl formate molecule (HCOOCH3) is one of the most abundant molecules observed in hot molecular cores. Together with acetic acid and sugar glycolaldehyde, these C2H4O2 are first triad isomers detected interstellar clouds. However, observations point to a high enhancement abundance formate, which can reach up 100 times amount its second isomer, acid. observational difference between has been subject several works, invoking different formation pathways or survival rates. In this work we...
Autoionization spectra of CH2Cl2 and CD2Cl2 molecules after Cl 2p excitation are studied. The two molecular atomic Auger transitions examined assigned. contribution is lower in the deuterated molecule. In addition, to support presence ultrafast dissociation mechanism dichloromethane molecule, a series high-level ab initio quantum mechanical calculations were performed at multiconfigurational self-consistent field (MCSCF) multireference configuration interaction (MRCI) levels theory. Minimum...
Using measured cross sections, empirical scaling laws are extracted for projectile stripping induced by collisions with a many-electron target. By both the sections and impact velocities, it is shown that single universal curve can be used to fit data multiple electron loss from negative ions, neutral particles, singly or multiply charged positive ions. The applies projectiles ranging hydrogen uranium collision energies below $\text{keV}∕\mathrm{u}$ hundreds of $\text{MeV}∕\mathrm{u}$. At...
Charge-state-correlated total cross sections for projectile-electron loss, capture, and target ionization in ${\mathrm{C}}^{3+}\text{\ensuremath{-}}\mathrm{Ne}$ collisions have been measured calculated at absolute energies the few MeV regime. The calculations are based on a recently proposed coupled mean-field approach which combines set of nonperturbative single-particle initial projectile electrons with another one electrons. basis generator method has used to solve these equations. Very...
The presence of methyl alcohol or methanol (CH$_3$OH) in several astrophysical environments has been characterized by its high abundance that depends on both the production rate and destruction rate. In present work, photoionization photodissociation processes have experimentally studied, employing soft X-ray photons (100-310 eV) from a toroidal grating monochromator (TGM) beamline Brazilian Synchrotron Light Laboratory (LNLS). Mass spectra were obtained using photoelectron photoion...
We present experimental results obtained from photoionization and photodissociation processes of abundant interstellar CH3-X type organic molecules like methanol (CH3OH), methylamine (CH3NH2) acetonitrile (CH3CN) as alternative route for the production H+3 in star-forming environments. The measurements were taken at Brazilian Synchrotron Light Laboratory (LNLS), employing soft X-ray photons with energies between 200 310 eV time-of-flight (TOF) mass spectrometry. Mass spectra using...
A comparative study for the fragmentation of a CH2Cl2 molecule has been performed collisions with 0.2–2.0 MeV H+ beam and 12.0–90.0 eV photons using time-of-flight coincidence technique. Branching ratios products have determined as function energy projectiles. The present results show that more proton increases, pattern resembles corresponding photon impact spectra at lower energies. For instance, 2.0 impact, closely hν = 60 eV. From analysis peak shapes, were found to be formed low kinetic...
Absolute total-, single-, and multiple-electron-loss cross sections are measured for $({\mathrm{Ar}}^{+}\ensuremath{-},$ ${\mathrm{Ar}}^{2+}\ensuremath{-},$ ${\mathrm{Xe}}^{3+})\ensuremath{-}(\mathrm{Ne},$ ${\mathrm{N}}_{2},$ Ar) collisions at 0.74 1.4 MeV/u. In addition, a many-body classical trajectory Monte Carlo model was used to calculate total- ${\mathrm{Ar}}^{+}$ impact. For ${\mathrm{N}}_{2}$ Ar targets, excellent agreement between the calculated is found; Ne target experimental data...
We have measured double-electron capture cross sections for ${\text{Li}}^{3+}$ projectiles and He targets in the 2.0--5.5 MeV energy range (3.4--5.6 a.u. velocity range). Double-electron-capture this collision system were before, but only at relatively lower energies. There is a good agreement between three available sets of experimental data double end present interval, i.e., where ranges from different measurements overlap. The other channels that include single ionization, capture,...
Absolute charge-state-correlated cross sections for projectile electron loss, capture, and target multiple ionization in collisions between ${\mathrm{C}}^{3+}$ ions noble gases have been measured energies $1.3$ $3.5$ MeV. The data compared with other similar absolute existent the literature several projectiles. Calculations single-loss$\ensuremath{-}$multiple-ionization channel performed screening mode, using both an extended version of classical-impulse free-collision model plane-wave Born...
Pure multiple ionization cross sections of Ne by B${}^{2+}$ projectiles have been measured in the energy range 0.75 to 4.0 MeV and calculated using continuum distorted wave-eikonal initial state approximation. The experiment calculations show that B${}^{2+}$, principally for production highly charged recoils, is strongly enhanced when compared bare projectile with same charge state, He${}^{2+}$, at velocities.
The center of mass kinetic energy release distribution (KERD) spectra selected ionic fragments, formed through dissociative single and double photoionization CH2Cl2 at photon energies around the Cl 2p edge, were extracted from shape width experimentally obtained time-of-flight (TOF) distributions. KERD exhibit either smooth profiles or structures, depending on moiety energy. In general, heavier lower their average KERDs are. contrast, light H(+) fragments are observed with centered 4.5-5.5...
Doubly differential cross sections for single and multiple ionization of Ar have been measured 500, 750, 1000 eV electron impact. The were as a function projectile energy loss scattering angle. range was 0--85 % the initial angles between $\ifmmode\pm\else\textpm\fi{}22\ifmmode^\circ\else\textdegree\fi{}.$ data put on an absolute scale by normalizing to total available in literature found be good agreement with impact from DuBois Rudd. For 750 impact, comparison made present positron...
Fragments from organic molecule dissociation (such as reactive ions and radicals) can form interstellar complex molecules like amino acids. The goal of this work is to experimentally study photoionization photodissociation processes acetic acid (CH3COOH), a glycine (NH2CH2COOH) precursor molecule, by soft X-ray photons. measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), employing photons toroidal grating monochromator (TGM) beamline (100–310 eV). Mass spectra...
The main purpose of this paper is to add the list examples how cell phones may be used as teaching tools in classroom.1 One very interesting example comes from study projectile motion, classical “cannon ball” problem. This problem central kinematics, first topic a student meets physics. Our approach exploits fact that these days almost all students carry cellular and vast majority have built-in cameras.
Absolute cross sections for the projectile single-electron loss and single- double-electron capture of ${\text{B}}^{2+}$ ions colliding with Ne Ar targets ${\text{C}}^{3+}$ targets, in energy range from 0.1 to 4.0 MeV, have been measured. Cross single channel calculated using classical Bohr-Lindhard model, showing good agreement experiment. In electron-loss process, calculations were performed both an extended version classical-impulse free-collision model plane-wave Born approximation...
We focus on the difficulties that visually impaired students have when dealing with graphics and diagrams in their study of geometrical optics. This case suggests practices use low cost materials, easy to find handle, provide a tactile perception for students. The activities employ light carry magnetic boards different types magnets, mainly shaped rubber magnet strips. A student-centered learning method, namely Karplus's circles, is adopted.