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Positive and negative ionic desorption from condensed formic acid photoexcited around the O 1s-edge: Relevance to cometary and planetary surfaces |
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| Authors: | DPP Andrade HM Boechat-Roberty EF da Silveira |
| Institution: | a Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21949-900 Rio de Janeiro, RJ, Brazil b Observatório do Valongo, Universidade Federal do Rio de Janeiro, Ladeira Pedro Antônio, 43, Centro, Rio de Janeiro, RJ, Brazil c Instituto de Pesquisa and Desenvolvimento, Universidade do Vale do Paraíba, Av. Shishima Hifumi, 2911, CEP: 12244-000 São José do Campos, SP, Brazil d Pontifícia Universidade Católica do Rio de Janeiro, Rua Marquês de São Vicente, 225, Gávea, 22453-900 Rio de Janeiro, RJ, Brazil |
| Abstract: | Photon stimulated ion desorption (PSID) studies have been performed in condensed formic acid using oxygen 1s-edge synchrotron radiation from the Brazilian synchrotron light source (LNLS), operating in a single-bunch mode. Ion formation was discussed in terms of the Auger stimulated ion desorption (ASID) and X-ray induced electron stimulated desorption (XESD) mechanisms. It is found that O 1s(C-OH) → π*(C O) and O 1s(CO) → 3s/σ*(HCO) transitions favored the production of C+, CH+, O+, O− and H− ions. The hydroxyl anion has not been observed while the hydroxyl cation showed low intensity or was absent. Some anion formation routes from dissociative reactions are suggested taking into account the positive ion yields. |
| Keywords: | Desorption induced by electronic transitions (DIET) Photon stimulated ion desorption (PSID) Surface photochemistry Desorption induced by photon stimulation Condensed formic acid Time-of-flight mass spectrometry Astrochemistry |
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