11 results on '"Boduch, P."'
Search Results
2. Heavy Ion Radiolysis of the Chiral Terpene α-pinene.
- Author
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de Barros, A L F, Ricca, A, Bychkova, A, da Costa, C A P, Costa, J W, Boduch, P, Rothard, H, da Silveira, E F, and Domaracka, A
- Subjects
HEAVY ions ,TERPENES ,RADIOLYSIS ,ION bombardment ,INTERSTELLAR molecules ,PROPANE ,ETHANES - Abstract
Radiolysis of α-pinene by 61.3 MeV
84 Kr15 + ions was analysed with the scope to simulate the effects of heavy ion cosmic ray bombardment on chiral molecules in the interstellar medium. The α-pinene ice samples were irradiated at 10 K and their chemical evolution was monitored by mid-infrared Fourier transform (FTIR) spectroscopy to characterize the reaction products and to determine the extent of racemization. The integrated band strengths have been obtained for all the neutral α-pinene vibrational bands using the experimental band integrated absorbances and the theoretical absolute intensities calculated along the column densities. In the current heavy ion bombardment experiments, small molecules were formed and the precursor, α-pinene, was destroyed instead of being racemized. Twelve hydrocarbons were produced (final fluence of 2.0 × 1012 ions cm−2 ): methane (CH4 ), acetylene (C2 H2 ), ethylene (C2 H4 ), propylene (C3 H6 ), propane (C3 H8 ), n-butane (C4 H10 ), butene (C4 H8 ), propyne (C3 H4 ), benzene (C6 H6 ), ethane (C2 H6 ), vinylacetylene (C4 H4 ), and 2-methyl-1,3-butadiene or isoprene (C5 H8 ). The highest formation cross-section (∼ 40 × 10−15 cm2 ) was observed for the C3 H4 and the lowest was for C3 H8 (∼ 3 × 10−15 cm2 ). The radiochemical yields for these molecules follow the same trends as those of their cross-sections. The atom budget calculation confirms that all the expected products have been generated during the radiolysis and supports the conclusion that the proposed A values are accurate. The α-pinene sputtering yield for this ion beam was found to be Y0 = 1.84 × 106 molecules per impact. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
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3. Valine Radiolysis by H+, He+, N+, and S15+ MeV Ions
- Author
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Cíntia A. P. da Costa, Gabriel S. Vignoli Muniz, Philippe Boduch, Hermann Rothard, and Enio F. da Silveira
- Subjects
amino acid ,valine ,mev ion irradiation ,radiolysis ,infrared absorption spectroscopy ,destruction cross section ,stopping power dependence ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Radiolysis of biomolecules by fast ions has interest in medical applications and astrobiology. The radiolysis of solid D-valine (0.2−2 μm thick) was performed at room temperature by 1.5 MeV H+, He+, N+, and 230 MeV S15+ ion beams. The samples were prepared by spraying/dropping valine-water-ethanol solution on ZnSe substrate. Radiolysis was monitored by infrared spectroscopy (FTIR) through the evolution of the intensity of the valine infrared 2900, 1329, 1271, 948, and 716 cm−1 bands as a function of projectile fluence. At the end of sample irradiation, residues (tholins) presenting a brownish color are observed. The dependence of the apparent (sputtering + radiolysis) destruction cross section, σd, on the beam stopping power in valine is found to follow the power law σd = aSen, with n close to 1. Thus, σd is approximately proportional to the absorbed dose. Destruction rates due to the main galactic cosmic ray species are calculated, yielding a million year half-life for solid valine in space. Data obtained in this work aim a better understanding on the radioresistance of complex organic molecules and formation of radioproducts.
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- 2020
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4. Cosmic-ray sputtering of interstellar ices in the electronic regime: A compendium of selected literature yields.
- Author
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Dartois, E., Chabot, M., da Costa, C. A. P., Nguyen, T., Rojas, J., Duprat, J., Augé, B., Domaracka, A., Rothard, H., and Boduch, P.
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COSMIC rays ,ICE sheets ,MICROPHYSICS ,ENERGY transfer ,LOW temperatures ,RADIOLYSIS - Abstract
Aims. With this article, we aim to provide the sputtering yields for molecular species of potential astrophysical interest and in the electronic regime of interaction characteristic of cosmic rays. We specifically target molecules that are constitutive of interstellar ice mantles. Methods. We used a compendium of existing data on electronic sputtering to calculate the prefactors leading to the generalisation of the stopping-power-dependent sputtering yield for many species condensing at low temperature. In addition, we present new experimental results to constrain the yield for solid CH
4 , C6 , and CH3 CN. Results. Electronic sputtering is constrained using literature data for H2 , HD, D2 , Ne, N2 , CO, Ar, O2 , Kr, Xe, CO2 , SO2 , NH3 , S, H2 O, D2 O, CH3 OH, Leucine, C20 H12 , C24 H12 , and C60 . A first-order relation with the sublimation enthalpy is derived, which allows us to predict the sputtering yield within an order of magnitude for most species. The fluctuations around the mean are partly assignable to the differences in resilience towards radiolysis for individual species, and partly to the micro-physics details of the energy transfer to the lattice. [ABSTRACT FROM AUTHOR]- Published
- 2023
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5. Radiolysis of NH3:CO ice mixtures – implications for Solar system and interstellar ices.
- Author
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de Barros, A L F, Bergantini, A, Domaracka, A, Rothard, H, Boduch, P, and da Silveira, E F
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SOLAR system ,FOURIER transform spectroscopy ,INTERSTELLAR medium ,CARBAMIC acid ,RADIOLYSIS ,ASTROCHEMISTRY ,COSMIC rays ,HEAVY ions - Abstract
Experimental results on the processing of NH3:CO ice mixtures of astrophysical relevance by energetic (538 MeV
64 Ni24+ ) projectiles are presented. NH3 and CO are two molecules relatively common in interstellar medium and Solar system; they may be precursors of amino acids.64 Ni ions may be considered as representative of heavy cosmic ray analogues. Laboratory data were collected using mid-infrared Fourier transform spectroscopy and revealed the formation of ammonium cation (NH |$_4^+$|), cyanate (OCN− ), molecular nitrogen (N2 ), and CO2 . Tentative assignments of carbamic acid (NH2 COOH), formate ion (HCOO− ), zwitterionic glycine (NH |$_3^+$| CH2 COO− ), and ammonium carbamate (NH |$_4^+$| NH2 COO− ) are proposed. Despite the confirmation on the synthesis of several complex species bearing C, H, O, and N atoms, no N–O-bearing species was detected. Moreover, parameters relevant for computational astrophysics, such as destruction and formation cross-sections, are determined for the precursor and the main detected species. Those values scale with the electronic stopping power (Se ) roughly as σ ∼ a S |$_\mathrm{ e}^n$| , where n ∼ 3/2. The power law is helpful for predicting the CO and NH3 dissociation and CO2 formation cross-sections for other ions and energies; these predictions allow estimating the effects of the entire cosmic ray radiation field. [ABSTRACT FROM AUTHOR]- Published
- 2020
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6. Radiolysis of Ices by Cosmic-Rays: CH4 and H2O Ices Mixtures Irradiated by 40 MeV 58Ni11+ Ions.
- Author
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Mejía, C., Barros, A. L. F. de, Rothard, H., Boduch, P., and da Silveira, E. F.
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FOURIER transform spectroscopy ,ICE nuclei ,RADIOLYSIS ,ICE sheets ,ICE ,COSMIC rays ,COLD regions - Abstract
Physico-chemical modifications induced by swift heavy ions on methane-water (CH
4 :H2 O) ices at 15 K are analyzed. Ice films, at concentrations of (1:3) and (1:15), were irradiated by 40 MeV58 Ni11+ ions. Fourier transform transmission spectroscopy in the mid-range was used to monitor the evolution ices at 15 K as a function of projectile fluence. New IR bands appearing for the irradiated (CH4 :H2 O) (1:3) ice are attributed to the synthesized molecules: C3 H8 , HCO, H2 CO, CO, CO2 , H2 O2 , HCOOH, CH3 OH, C2 H5 OH, and CH3 CHO. For the irradiated (CH4 :H2 O) (1:15) ice, the abundances of the compounds containing two carbons atoms are lower than those for the (1:3) ice; in contrast, CH3 OH and H2 O2 abundances increase when compared to the values obtained with the (1:3) ice. After irradiation, the ices were warmed up until 110 K, when the IR spectra reveal features of complex organic molecules. The destruction and formation cross sections and the sputtering yields of the ice mixtures are estimated. These findings provide possible pathways for the occurrence of compounds rich in C, O, and H, which are indeed observed in the cold regions of the universe such as ices in grain mantles of the interstellar medium and circumstellar envelopes. [ABSTRACT FROM AUTHOR]- Published
- 2020
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7. Chemical reactions in the nitrogen--acetone ice induced by cosmic ray analogues: relevance for the Solar system.
- Author
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de Barros, A. L. F., Andrade, D. P. P., da Silveira, E. F., Alcantara, K. F., Boduch, P., and Rothard, H.
- Subjects
TRANS-Neptunian objects ,SOLAR system ,RADIOLYSIS ,COSMIC rays ,CHEMICAL synthesis ,ACETONE ,NITROGEN ,IRRADIATION - Abstract
The radiolysis of 10:1 nitrogen:acetone mixture, condensed at 11 K, by 40 MeV
58 Ni11+ ions is studied. These results are representative of studies concerning Solar system objects, such as transneptunian objects, exposed to cosmic rays. Bombardment by cosmic rays triggers chemical reactions leading to synthesis of larger molecules. In this work, destruction crosssections of acetone and nitrogen molecules in solid phase are determined and compared with those for pure acetone. The N2 column density decreases very fast indicating that, under irradiation, nitrogen leaves quickly a porous sample. The most abundant molecular species formed in the radiolysis are C3 H6 , C2 H6 , N3 , CO, CH4 and CO2 . Some N-bearing species are also formed, but with low production yield. Dissolving acetone in nitrogen decreases the formation cross-sections of CH4 , CO2 and H2 CO, while increases those for CO and C2 H6 species. This fact may explain the presence of C2 H6 in Pluto's surface where CH4 is not pure, but diluted in an N2 matrix. The formation of more complex molecules, such as HNCO and, possibly, glycine is observed, suggesting the formation of small prebiotic species in objects beyond Neptune from acetone diluted in a N2 matrix irradiated by cosmic rays. [ABSTRACT FROM AUTHOR]- Published
- 2018
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8. Formation of nitrogen- and oxygen-bearing molecules from radiolysis of nitrous oxide ices - implications for Solar system and interstellar ices.
- Author
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de Barros, A. L. F., da Silveira, E. F., Fulvio, D., Boduch, P., and Rothard, H.
- Subjects
RADIOLYSIS ,NITROUS oxide ,SOLAR system ,INTERSTELLAR medium ,FOURIER transform infrared spectroscopy - Abstract
The radiolysis of pure N
2 O ice at 11 and 75 K by 90 MeV136 Xe23+ ion irradiation has been studied by Fourier-transformed infrared spectroscopy (FTIR). Six daughter molecular species have been observed: NO2 , (NO)2 , N2 O3 , N2 O4 , N2 O5 , and O3 . The chemical evolution of the new molecules formed in the sample was followed by the measurement of the column densities of the precursor and products as a function of the beam fluence. This procedure allows the determination of their formation and dissociation cross-sections. Other processes monitored by FTIR were sublimation (non-existent at 11 K, but present at 75 K) and ice compaction by the ion beam. Comparison between results obtained for the 11 and 75 K ices shows that formation and destruction cross-sections are higher (for light products) or much higher (for heavy products) at 75 K. This enhancement of chemical activity at higher temperature should not be attributed to higher projectile ionization rate but rather to a higher mobility of the radiolysis products in an ice undergoing slow sublimation. Although N2 O ice has not yet been observed in space, it is reasonable to expect its occurrence since N and O are very abundant and reactive. Furthermore, if this ice is actually absent, the knowledge of the chemical-physical processes induced by ion irradiation on N2 O ice at low temperature is necessary to explain its depletion. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
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9. Ion processing of ices and the origin of SO2 and O3 on the icy surfaces of the icy jovian satellites.
- Author
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Boduch, P., Brunetto, R., Ding, J.J., Domaracka, A., Kaňuchová, Z., Palumbo, M.E., Rothard, H., and Strazzulla, G.
- Subjects
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SATELLITES of Jupiter , *SULFUR dioxide , *ION implantation , *OZONE , *ULTRAVIOLET spectroscopy , *RADIOLYSIS - Abstract
We present new experimental results relative to 144 keV S 9 + or Ar 9 + ion implantation in targets made of oxygen rich frozen gases (O 2 , CO 2 ) and mixtures with water ice. Spectra in the UV (200–400 nm) range have been obtained before and after implantation. The targets have been selected because they can be representative of the parent molecules from which SO 2 and O 3 , observed to be present on the surfaces of Jupiter’s icy Moons, could be formed due to radiolysis induced by the abundant magnetospheric ions. The results indicate that sulfur dioxide is not detectable after sulfur implantation in oxygen bearing species. Ozone is formed after argon and sulfur ion implantation. Sulfur implantation in O 2 and CO 2 targets also induces the formation of a band centered at about 255 nm (that we tentatively attribute to SO 3 − radicals). In the mixtures with water the band appears initially at the same wavelength and shifts to about 247 nm at higher ion fluences possibly indicating the formation of sulfite (HSO 3 − ) ions. An absorption band observed on Ganymede is well fitted by using three components: ozone, sulfite ions and a not identified component having an absorption band centered at 298 nm. In all of the studied cases ion implantation produces a spectral reddening over the investigated spectral range (200–400 nm) that well mimics the observed spectral slopes of Jupiter’s icy satellites. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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10. Erratum: Radiolysis of N 2 O:CO 2 Ice by Heavy Ions: Simulation of Cosmic Ray Effects.
- Author
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Pereira, R C, de Barros, A L F, Fulvio, D, Boduch, P, Rothard, H, and da Silveira, E F
- Subjects
RADIOLYSIS ,HEAVY ions ,COSMIC rays - Published
- 2019
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11. RADIOLYSIS OF NITROGEN AND WATER-ICE MIXTURE BY FAST IONS: IMPLICATIONS FOR KUIPER BELT OBJECTS
- Author
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Boduch, P. [Centre de Recherche sur les Ions, les Matériaux et la Photonique CIMAP-GANIL (CEA-CNRS-ENSICAEN-UCBN), BP 5133, Boulevard Henri Becquerel, F-14070 Caen Cedex 05 (France)]
- Published
- 2015
- Full Text
- View/download PDF
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