A5003996317- Astrophysics and Star Formation Studies
- Advanced Chemical Physics Studies
- Atomic and Molecular Physics
- Atmospheric Ozone and Climate
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Stellar, planetary, and galactic studies
- Atmospheric chemistry and aerosols
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Inorganic Fluorides and Related Compounds
- Crystallography and molecular interactions
- Ion-surface interactions and analysis
- Astronomy and Astrophysical Research
- SAS software applications and methods
- Galaxies: Formation, Evolution, Phenomena
- Various Chemistry Research Topics
- Synthesis and Properties of Aromatic Compounds
- Space Exploration and Technology
- Radiation Therapy and Dosimetry
- Organic and Molecular Conductors Research
- Advanced Mathematical Theories and Applications
Universidade Federal do Rio de Janeiro
2013-2023
Valongo Observatory
2013-2023
Hospital Universitário Antônio Pedro
2006-2023
Universidade do Vale do Paraíba
2010
Pontifical Catholic University of Rio de Janeiro
2008
Universidade Federal de São Carlos
2008
National Observatory
1995
Evidence is mounting that the small bodies of our Solar System, such as comets and asteroids, have at least partially inherited their chemical composition from first phases System formation. It then appears molecular complexity these most likely related to earliest stages star therefore important characterize understand how evolution changes with solar-type protostellar evolution. We present here Large Program "Astrochemical Surveys At IRAM" (ASAI). Its goal carry out unbiased millimeter...
Interstellar molecules with a peptide link -NH-C(=O)-, like formamide (NH$_2$CHO), acetamide (NH$_2$COCH$_3$) and isocyanic acid (HNCO) are particularly interesting for their potential role in pre-biotic chemistry. We have studied emission the protostellar shock regions L1157-B1 L1157-B2, IRAM 30m telescope, as part of ASAI Large Program. Analysis line profiles shows that arises from outflow cavities associated B1 B2. Molecular abundance $\approx~(0.4-1.1)\times 10^{-8}$ $(3.3-8.8)\times...
An experimental photochemistry study involving gas- and solid-phase amino acids (glycine, DL-valine, DL-proline) nucleobases (adenine uracil) under soft X-rays was performed. The aim to test the molecular stabilities of essential biomolecules against ionizing photon fields inside dense clouds protostellar disks analogs. In these environments, main energy sources are cosmic rays X-rays. measurements were taken at Brazilian Synchrotron Light Laboratory (LNLS), employing 150 eV photons. In-situ...
Despite the extensive search for glycine (NH2CH2COOH) and other amino acids in molecular clouds associated with star-forming regions, only upper limits have been derived from radio observations. Nevertheless, two of glycine's precursors, formic acid acetic acid, abundantly detected. Although both precursors may lead to formation, efficiency reaction depends on their abundance survival presence a radiation field. These facts could promote some favoritism pathways gas phase solid (ice)....
The abundances of molecules and ions depend on the mechanisms their formation destruction that can occur both in gas phase condensed grain surfaces. Photodesorption surface species may explain relative high gaseous neutral or ionic detected cold environments. X-ray photons from young stars are able to penetrate dense regions inside protoplanetary discs, leading molecular dissociation desorption photo-products icy mantles. This paper aims experimentally investigate contribution ion methanol...
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...
In 2005 we suggested a relation between the optimal locus of gas giant planet formation, prior to migration, and metallicity host star, based on core accretion model radial profiles dust surface density temperature. At that time, less than two hundred extrasolar planets were known, limiting scope our analysis. Here take into account expanded statistics allowed by new discoveries, in order check validity some premises. We compare predictions with present available data results for different...
ABSTRACT The infrared signatures of polycyclic aromatic hydrocarbons (PAHs) are observed in a variety astrophysical objects, including the circumnuclear medium active galactic nuclei (AGNs). These sources highly energetic photons (0.2–10 keV), exposing PAHs to harsh environment. In this work, we examined experimentally photoionization and photostability naphthalene (C10H8), anthracene (C14H10), 2-methyl-anthracene (C14H9CH3), pyrene (C16H10) upon interaction with 275, 310, 2500 eV....
Naphthalene (C10H8) is the simplest polycyclic aromatic hydrocarbon (PAH) and an important component in a series of astrochemical reactions involving hydrocarbons. Its molecular charge state affects stability its isomeric structures, which specially relevant ionised astrophysical environments. We thus perform extensive computational search for low-energy structures neutral, singly, multiply charged naphthalene isomers with states +q = 0-4 investigate their geometric properties bonding...
As part of a systematic, quantitative study the angle dependence core-level-electron excitation by electron impact, we have determined generalized oscillator strength (GOS) for carbon 1s(2${\mathrm{\ensuremath{\sigma}}}_{\mathit{g}}$\ensuremath{\rightarrow}2${\mathrm{\ensuremath{\pi}}}_{\mathit{u}}$) transition in ${\mathrm{CO}}_{2}$. The experimental results were obtained at an impact energy 1290 eV, angular range 2\ifmmode^\circ\else\textdegree\fi{}--14\ifmmode^\circ\else\textdegree\fi{},...
Absolute values for the generalized oscillator strength (GOS) 3${p}^{6}$\ensuremath{\rightarrow}3${p}^{5}$(4s,4s') transitions in argon ${(}^{1}$${\mathrm{S}}_{0}$) have been determined by 1-keV electron scattering. The relative differential cross section, measured angular range of 1.0\ifmmode^\circ\else\textdegree\fi{}--15\ifmmode^\circ\else\textdegree\fi{}, has made absolute comparison with known elastic and results converted to GOS. GOS's also calculated, using both first Born Glauber...
Benzene molecules, present in the proto-planetary nebula CRL 618, are ionized and dissociated by UV X-ray photons originated from hot central star its fast wind. Ionic species free radicals produced these processes can lead to formation of new organic molecules. The aim this work is study photoionization photodissociation benzene molecule, using synchrotron radiation time flight mass spectrometry. Mass spectra were recorded at different energies corresponding vacuum ultraviolet (21.21 eV)...
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...
Abstract Polycyclic aromatic hydrocarbons (PAHs), comprised of fused benzene (C 6 H ) rings, emit infrared radiation (3–12 μ m) due to the vibrational transitions C–H bonds rings. The 3.3 m band is generally accompanied by at 3.4 assigned vibration aliphatic compounds such as PAHs with an excess peripheral atoms (H n –PAHs). Herein we study stability fully hydrogenated (or cyclohexane, C 12 under impact stellar in photodissociation region (PDR) NGC 7027. Using synchrotron and time-of-flight...
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...
In this work, the fragmentation, survival, and chemical reactions of formic acid (HCOOH) molecules condensed at 56 K are analyzed using plasma desorption mass spectrometry (PDMS) photon-stimulated ion (PSID) in an effort to simulate effects energetic charged particles (e.g., cosmic rays) radiation fields on interstellar/cometary ices. The measurements were taken Brazilian Synchrotron Light Laboratory (LNLS), employing soft X-ray photons (535.1 eV) ions (∼65 MeV) obtained as 252Cf fission...
Acetone, one of the most important molecules in organic chemistry, also a precursor prebiotic species, was found interstellar medium associated with star-forming environments. The mechanisms proposed to explain gas phase abundance acetone are based on grain mantle chemistry. High energy photons coming from stellar radiation field nearby stars interact ice mantles dust grains leading photoionization, photodissociation, and photodesorption processes. In this work we investigate photostability...
Non-thermal desorption by electron impact constitutes an important route which neutral and ionic fragments from simple nitrile-bearing ices may be delivered back to the gas-phase of astrophysical environments, contributing production more complex molecules.
We have determined theoretical values for the excitation energy, optical oscillator strength, and generalized strength (GOS), as well experimental GOS C 1s (1${\mathrm{\ensuremath{\sigma}}}_{\mathit{g}}$\ensuremath{\rightarrow}1${\mathrm{\ensuremath{\pi}}}_{\mathit{g}}$) (1${\mathrm{\ensuremath{\sigma}}}_{\mathit{u}}$\ensuremath{\rightarrow}1${\mathrm{\ensuremath{\pi}}}_{\mathit{g}}$) transitions in ${\mathrm{C}}_{2}$${\mathrm{H}}_{2}$ molecule. In order to study influence of relaxation,...
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...
We present here a systematic search for cyanopolyynes in the shock region L1157-B1 and its associated protostar L1157-mm framework of Large Program "Astrochemical Surveys At IRAM" (ASAI), dedicated to chemical surveys solar-type star forming regions with IRAM 30m telescope. Observations millimeter windows between 72 272 GHz permitted detection HC$_3$N $^{13}$C isotopologues, HC$_5$N (for first time protostellar region). In shock, analysis line profiles shows that emission arises from outflow...