title: Electron transfer processes in potassium collisions with 5-fluorouracil and 5-chlorouracil.
abstract: Electron transfer to uracil (U), 5-chlorouracil (5-ClU) and 5-fluorouracil (5-FU) yielding anion formation has been investigated in 30-100 eV potassium-molecule collisions. The rich fragmentation patterns of all three molecules suggest that electron transfer in collisions with electronegative neutrals may cause efficient damage to RNA. The main ring fragment anion in all the mass spectra was NCO(-) while the production of X(-) (X = F, Cl) was a strong decomposition of the halouracil temporary negative ions. Cl(-) was the most intense fragment anion in the 5-chlorouracil measurements, whereas NCO(-) production dominated in the U and 5-FU data. Arguments based on energetics and vibrational dynamics have been proposed to explain these differences. Electronic coupling between dipole- and valence-bound states may play a particularly important role in the fragmentation pathways of the 5-ClU parent anion. The stabilizing influence of the potassium cation following electron transfer (ionic scattering) on the observed fragmentation patterns is discussed, notably in the context of comparisons with free electron attachment processes.
authors.affiliation: Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, FCT-Universidade Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Ferreira da Silva
authors.forename: D
authors.initials: D
authors.lastname: Almeida
authors.forename: R
authors.initials: R
authors.lastname: Antunes
authors.forename: G
authors.initials: G
authors.lastname: Martins
authors.forename: Y
authors.initials: Y
authors.lastname: Nunes
authors.forename: S
authors.initials: S
authors.lastname: Eden
authors.forename: G
authors.initials: G
authors.lastname: Garcia
authors.forename: P
authors.initials: P
authors.lastname: Limão-Vieira
mesh_terms: D002412:Cations / Q000737:chemistry; D004579:Electron Transport; D005472:Fluorouracil / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D013816:Thermodynamics; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D002412:Cations; D014498:Uracil; C010889:5-chlorouracil; D011188:Potassium; D005472:Fluorouracil