Título: | IONIC DESORPTION INDUCED BY ENERGETIC HEAVY IONS ON ASTROPHYSICAL ICES: H2O, C2H2, C2H6 AND N2O | ||||||||||||
Autor: |
PABLO RAMON BATISTA OLIVEIRA |
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Colaborador(es): |
ENIO FROTA DA SILVEIRA - Orientador |
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Catalogação: | 26/JAN/2023 | Língua(s): | PORTUGUESE - BRAZIL |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=61827&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=61827&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.61827 | ||||||||||||
Resumo: | |||||||||||||
A PDMS-252Cf-TOF (Time-of-Flight Plasma Desorption Mass Spectrometry)
mass spectrometer was used to analyze condensed samples of pure water
and mixtures of H2O:C2H2, H2O:C2H6 and H2O:N2O, at temperatures between
10 and 100 K. The ions desorbed due to the projectile impact were identified
and their desorption yields determined. It is observed that the yield distributions
as a function of the mass of the ions can be described by the sum of
two exponentials. This result strongly suggests that two processes of aggregate
formation occur: one, via direct emission of fragments from the solid and the
other, via recombination of fragments in the gas phase. For pure H2O, the
main desorbed aggregates are: ((H2O)nH2O+, (H2O)nH3O+, On
+, (H2O)nO−,
(H2O)nOH− and On
−. For mixtures of ices H2O:C2H2 and H2O:C2H6, the series
(C2H2)n
+ and (C2H6)n
+ are observed. For H2O:N2O, the series Nn
+, (O)nN2
+,
(O)nN2−, (O)nN4−, and (N2)nNO+ are the most abundant.
Density Functional Theory (DFT), at the B3LYP/6-31G level, was
used to calculate the molecular stability of emitted secondary molecular ions.
Calculations for the C2Hm
+ structures (with m = 1 to 6) generated 26 stable
structures. The stability curves per mass/charge obtained are compared with
those obtained experimentally for the desorption yields per mass/charge for the
same ions. Such methodology is used to predict the most likely conformations
of the desorbed ions.
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