20-150-keV proton-impact-induced ionization of uracil: Fragmentation ratios and branching ratios for electron capture and direct ionization
- Universite de Lyon, F-69003, Lyon (France)
Fragmentation ratios and branching ratios are measured for ionization and dissociative ionization for 20-150 keV (0.9-2.4v{sub 0}) proton collisions with gas-phase uracil molecules. Through event-by-event determination of the postcollision projectile charge, it is possible 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 spectra for both processes, EC induces dissociation with greater efficiency than DI in the impact energy range of 35-150 keV (1.2-2.4v{sub 0}). In this range EC is also less abundant than DI with a branching ratio for EC/total ionization of <50%. Moreover, whereas fragmentation ratios do not change with energy in the case of EC, DI mass spectra show a tendency for increased fragmentation at lower impact energies.
- OSTI ID:
- 21388736
- Journal Information:
- Physical Review. A, Journal Name: Physical Review. A Journal Issue: 1 Vol. 81; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AZINES
BARYONS
BRANCHING RATIO
CAPTURE
CHARGED PARTICLES
COLLISIONS
DIMENSIONLESS NUMBERS
EFFICIENCY
ELECTRON CAPTURE
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
FRAGMENTATION
HADRONS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IONIZATION
IONS
KEV RANGE
KEV RANGE 10-100
KEV RANGE 100-1000
MASS SPECTRA
MOLECULES
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROTONS
PYRIMIDINES
SPECTRA
URACILS