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International Journal of Mass Spectrometry 292 (2010) 53-63
Mass spectrometry (fragmentation ratios) of DNA base molecules following 80 keV proton impact with separation of direct ionization and electron capture processes
J. Tabet1, S. Eden1, S. Feil1, H. Abdoul-Carime1, B. Farizon1, M. Farizon1, S. Ouaskit2, T.D. Märk3

The first fragmentation ratios are presented for the ionization and dissociative ionization of gas-phase DNA bases following 80 keV (1.8 v0) proton impact. Event-by-event determination of the projectile charge state after collision enables also to distinguish the relative contributions of electron capture (EC) by the projectile from direct ionization (DI) of the target molecule (without projectile neutralization) thus yielding branching rations for these two different ionization processes. Results have been compared with recent similar experiments on uracil [Tabet et al. unpublished] and water [Gobet et al. Phys. Rev. A 70 (2004) 062716]. Although in all cases both processes (EC and DI) produced the same fragment ion groups in the mass spectra, fragmentation is for EC larger than for DI. Moreover the fragmentation ratio for dissociative ionization was observed to be for thymine larger than for adenine, cytosine, and uracil.
1 :  IPNL - Institut de Physique Nucléaire de Lyon
2 :  Université HassanII-Mohammedia, Faculté des Sciences
3 :  Institut für Ionenphysik und Angewandte Physik
Physique/Physique/Agrégats Moléculaires et Atomiques

Physique/Physique/Physique Atomique
DNA bases – adenine – cytosine – thymine – uracil – proton impact – ionization – dissociative ionization – electron capture – mass spectrometry
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DNA-SM-2009.pdf(640 KB)