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150 results on '"da Silveira, E.F."'

5. SEM analysis of ion implanted SiC

Author

Malherbe, Johan B., van der Berg, N.G., Botha, A.J., Friedland, E., Hlatshwayo, T.T., Kuhudzai, R.J., Wendler, E., Wesch, W., Chakraborty, P., and da Silveira, E.F.

Published
2013
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18. Theoretical and experimental analysis of ammonia ionic clusters produced by [sup.252.Cf] fragment impact on an N[H.sub.3] ice target

Author

Fernandez-Lima, F.A., Ponciano, C.R., Nascimento, M.A. Chaer, and Da Silveira, E.F.

Subjects
Ammonia -- Atomic properties, Ammonia -- Structure, Cluster theory (Nuclear physics) -- Analysis, Density functionals -- Usage, Chemicals, plastics and rubber industries
Abstract

Positive and negatively charged ammonia clusters produced by the impact of [sup.252.Cf] fission fragments (FF) on an N[H.sub.3] ice target are examined theoretically and experimentally. The stability analysis has predicted that the [(N[H.sub.3]).sub.4]N[H.sub.4.sup.+] and the even negative clusters [[(N[H.sub.3]).sub.n]N[H.sub.2.sup.-]], n = 2,4, and 6] are the most stable ones, in perfect agreement with the experimental results.

Published
2006

36. Destruction of CO ice and formation of new molecules by irradiation with 28 keV O6+ ions

Author

de Barros, A.L.F., Seperuelo Duarte, E., Farenzena, L. S., da Silveira, E.F., Domaracka, Alicja, Rothard, Hermann, Boduch, Philippe, Departamento de Disciplinas Basicas e Gerais (CEFET-RJ), CEFET-RJ, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Grupo de Fisica e Astronomia (CEFET/Quimica de Nilopolis), CEFET-RN : Federal Center for Technological Education of Rio Grande do Norte, Pontifícia Universidade Católica, Departamento de Física (PUC), Pontifícia Universidade Católica, Departamento de Física [Universidade Federal de Santa Catarina], Universidade Federal de Santa Catarina = Federal University of Santa Catarina [Florianópolis] (UFSC), Brassy, Chantal, Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Solar wind, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], ices, [PHYS.COND.CM-GEN] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [CHIM.RADIO] Chemical Sciences/Radiochemistry, Methods, Astrophysics::Earth and Planetary Astrophysics, laboratory, [CHIM.RADIO]Chemical Sciences/Radiochemistry, Astrochemistry, Solar system
Abstract

International audience; The effect of solar wind on cometary ice was studied by using oxygen ions with energy near to that corresponding to their maximum abundance in space for bombarding CO ice. This gas was condensed on a CsI substrate at 14 K and irradiated by 28 keV 18O6+ ions up to a final fluence of 1.3 x 1016 cm-2. We have used a methodology in which the sputtering yields, the destruction rate of CO, and the rate of formation of new molecular species are determined by Fourier transform infrared spectroscopy (FTIR). In the current experiment, the condensation of a thin water ice film has prevented the CO sputtering. Quantities such as the dissociation yield, Yd (the number of ice molecules destroyed or dissociated per projectile impact), and the formation yield, Yf (the number of daughter molecules of a given species formed per projectile) are found to be more appropriate and useful than using an integrated or average cross section, since the projectiles are slowing down in the ice from their initial energy until zero velocity (implantation).

Published
2011

37. Heavy ion irradiation of condensed CO2: sputtering and molecule formation

Author

Seperuelo Duarte, Eduardo, Boduch, Philippe, Rothard, Hermann, Been, Thierry, Dartois, E., Farenzena, L. S., Da Silveira, E.F., Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Pontifícia Universidade Católica, Departamento de Física (PUC), Pontifícia Universidade Católica, Grupo de Fisica e Astronomia (CEFET/Quimica de Nilopolis), CEFET-RN : Federal Center for Technological Education of Rio Grande do Norte, Institut d'astrophysique spatiale (IAS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Sud - Paris 11 (UP11), Departamento de Física [Universidade Federal de Santa Catarina], Universidade Federal de Santa Catarina = Federal University of Santa Catarina [Florianópolis] (UFSC), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
methods: laboratory, molecular processes, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], molecular data, Physics::Instrumentation and Detectors, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], techniques: spectroscopic
Abstract

International audience; Context : Ices present in different astrophysical environments are exposed to ion irradiation from cosmic rays (H to heavier than Fe) in the keV to GeV energy range. Aims : The objective of this work is to study the effects produced in astrophysical ices by heavy ions at relatively high energies (MeV) in the electronic energy loss regime and compare them with those produced by protons. Methods : C18O2 was condensed on a CsI substrate at 13 K and it was irradiated by 46 MeV 58Ni11+ up to a final fluence of 1.5 × 1013 cm−2 at a flux of 2 × 109 cm−2 s−1. The ice was analyzed in situ by infrared spectroscopy (FTIR) in the 5000−600 cm−1 range. Results : The CO2 destruction was observed, as well as the formation of other species such as CO, CO3, O3, and C3. The destruction cross section of CO2 is found to be 1.7×10−13 cm2, while those for the formation of CO, CO3, and O3 molecules are 1.6 × 10−13 cm2, 4.5 × 10−14 cm2, and 1.5 × 10−14 cm2, respectively. The sputtering yield of the CO2 ice is 4.0 × 104 molecules/impact, four orders of magnitude higher than for H projectiles at the same velocity. This allows us to estimate the contribution of the sputtering by heavy ions as compared to protons in the solar winds and in cosmic rays. Conclusions : The present results show that heavy ions play an important role in the sputtering of astrophysical ices. Furthermore, this work confirms the quadratic stopping power dependence of sputtering yields.

Published
2009

41. AODO: Secondary ion emission and surface modification

Author

Akcöltekin, S., primary, Alzaher, I., additional, Ban d’Etat, B., additional, Been, T., additional, Boduch, P., additional, Cassimi, A., additional, Hijazi, H., additional, Lebius, H., additional, Manil, B., additional, Ramillon, J.M., additional, Rothard, H., additional, Schleberger, M., additional, and da Silveira, E.F., additional

Published
2009
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