Heloisa Maria Boechat-Roberty

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Benzene molecules, present in the proto-planetary nebula CRL 618, are ionized and dissociated by UV and X-ray photons originated from the hot central star and by its fast wind. Ionic species and free radicals produced by these processes can lead to the formation of new organic molecules. The aim of this work is to study the photoionization and(More)
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 and acetic acid, have been abundantly detected. Although both precursors may lead to glycine formation, the(More)
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 and photodissociation processes of acetic acid (CH3COOH), a glycine (NH2CH2COOH) precursor molecule, by soft X-ray photons. The measurements were taken at(More)
Formic acid is much more abundant in the solid state, both in interstellar ices and cometary ices, than in the interstellar gas (ice/gas ∼ 104) and this point remains a puzzle. The goal of this work is to experimentally study ionization and photodissociation processes of HCOOH (formic acid), a glycine precursor molecule. The measurements were taken at the(More)
Espectros de perda de energia de elétrons foram obtidos para a molécula de hexafluoreto de enxofre na região da camada de valência (0 a 100 eV) com uma variação angular de 1.0° 15.0°. Os espectros foram medidos para uma energia de impacto de 1 keV. O estudo com variação angular sugere a presença de três transições proibidas na região de energia abaixo de 40(More)
We present experimental results obtained from photoionization and photodissociation processes of abundant interstellar CH3-X type organic molecules like methanol (CH3OH), methylamine (CH3NH2) and acetonitrile (CH3CN) as alternative route for the production of H+3 in interstellar and star forming environments. The measurements were taken at the Brazilian(More)
In order to simulate the effects of energetic charged particles present in the solar wind colliding with the cometary gaseous formic acid molecule (HCOOH), laboratory experiments have been performed. The absolute ionisation and dissociation cross sections for this molecule interacting with solar wind particles were measured employing fast electrons in the(More)
The incidence of high-energy radiation onto icy surfaces constitutes an important route for leading new neutral or ionized molecular species back to the gas phase in interstellar and circumstellar environments, especially where thermal desorption is negligible. In order to simulate such processes, an acetonitrile ice (CH3CN) frozen at 120 K is bombarded by(More)
Recent experimental results on negatively charged formic acid clusters generated by the impact of (252)Cf fission fragments on icy formic acid target are compared to quantum mechanical calculations. Structures for the clusters series, (HCOOH)nOH(-), where 2 < or = n < or = 4, are proposed based on ab initio electronic structure methods. The results show(More)