Doubly differential distribution of electron emission in ionization of uracil in collisions with 3.5-MeV/u bare C ions

Abstract

We report the energy and angular distribution of the electron emission from an RNA base molecule uracil in collisions with 3.5-MeV/u bare C ions. The absolute double differential cross sections (DDCS) are measured for emission energy between a few to 600 eV. The angular distributions are compared to those obtained for the O2 molecule in the same experiment. The single differential cross sections (SDCS) are also deduced. The energy and angular distributions of the DDCS and SDCS are compared with the state-of-the-art quantum-mechanical models based on continuum distorted wave-eikonal initial state (CDW-EIS) and correct boundary first Born (CB1) approximations which use a suitable molecular wave function for uracil. The models, however, give substantial deviations from the observed energy and angular distributions of the DDCS as well as SDCS. The CDW-EIS calculations are closer to the data compared to the CB1. In the case of uracil a large difference in the forward-backward emission of electrons was observed in comparison to that in collisions with an oxygen molecule

Angle-differential observation of plasmon electrons in the double-differential cross-section spectra of fast-ion-induced electron ejection fromC60

“…[40] for details). The same spectrometer has been widely used to investigate several features of Coulomb ionization in ion-atom or ion-molecule collisions using He, Ne, H 2 , or other heavier atoms and large biomolecules [1,38,[40][41][42]. However, in order to compare the shape of the two spectra arising from Ne and C 60 , the Ne data was normalized to that for C 60 at a given energy since the gas density, path length, and solid angles were different for the two cases.…”

“…The interest in these systems arises since one needs to understand the influence of the many-body nature on ionization and charge-transfer processes. In a recent study, it was shown that uracil, which is a ring-shaped organic molecule, has a dramatically large cross section for electron emission, particularly at forward angles, and this behavior cannot be explained in the realm of conventional ion-atom collision models [1]. Similarly, the collective excitation in polycyclic aromatic hydrocarbon (PAH) molecules [2], found in the interstellar medium, also influences their interaction with charged particles and photons.…”

Ionization of small molecules induced byH+, He+, andKovács1, Herczku2, Juhász3 et al. 2016Phys. Rev. A

“…In recent studies attention has turned to more complex systems, for instance collisions with large biomolecules [16,[20][21][22]. The experiments cover a wide energy range from a few keV up to ca.…”

“…100 MeV. Ionization by bare ions was investigated in detail by Tribedi and co-workers for a wide range of targets with emphasis on the two-center (TCE) and interference effects [21][22][23][24][25].…”

“…Numerous measurements have been focused on the direct ionization of nucleobases [16,[20][21][22]. Although the direct DNA damage is of particular interest, secondary processes significantly contribute to DNA lesions.…”