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20-150 keV proton impact induced ionization of uracil: fragmentation ratios and branching ratios for electron capture and direct ionization

Abstract : Fragmentation ratios have been measured for ionization and dissociative ionization for 20-150 keV (0.9-2.4 v0) proton collisions with gas-phase uracil molecules. Through event-by-event determination of the post-collision projectile charge, it is possible for the first time for such a key biomolecule to distinguish between electron capture (EC) by the incident proton and direct ionization (DI) without projectile neutralization. While the same fragment ion groups are observed in the mass spectrum for both processes, electron capture induces dissociation with greater efficiency than direct ionization in the impact energy range of 35-150 keV (1.2-2.4 v0). In this range electron capture is also less abundant than direct ionization with a branching ratio for electron capture / total ionization of < 50%. Moreover, whereas fragmentation ratios do not change with energy in case of electron capture, direct ionization mass spectra show a tendency for increased fragmentation at lower impact energies.
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http://hal.in2p3.fr/in2p3-00420485
Contributor : Dominique Girod <>
Submitted on : Tuesday, September 29, 2009 - 10:58:10 AM
Last modification on : Tuesday, November 19, 2019 - 2:37:39 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 8:27:08 PM

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J. Tabet, S. Eden, S. Feil, H. Abdoul-Carime, B. Farizon, et al.. 20-150 keV proton impact induced ionization of uracil: fragmentation ratios and branching ratios for electron capture and direct ionization. Physical Review A, American Physical Society, 2010, 81, 012711 [10 p.]. ⟨10.1103/PhysRevA.81.012711⟩. ⟨in2p3-00420485⟩

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