Cross section calculations for electron scattering from DNA and RNA bases

Abstract

Differential and integral cross sections for elastic electron collisions with uracil, cytosine, guanine, adenine and thymine have been calculated using the independent atom method with a static-polarization model potential for incident energies ranging from 50 to 4000 eV. Total cross sections for single electron-impact ionization of selected DNA and RNA bases have also been calculated with the binary-encounter-Bethe model from the ionization threshold up to 5000 eV. Cross sections within the investigated energy range, can be related to the molecular symmetry, the number of target electrons and molecular size; elastic and ionization processes are most efficient for guanine and adenine molecules, while the lowest cross sections were obtained for the uracil molecule. The ionization cross sections for cytosine, thymine, adenine and guanine are compared with those recently obtained with a semi-classical and binary-encounter-Bethe formalisms. No theoretical and experimental data for elastic electron scattering from DNA and RNA bases are available, but comparisons with calculations for molecules of similar size and geometry allows the validity of the theoretical approach to be verified.

Electron collisions with methyl-substituted ethylenes: Cross section measurements and calculations for 2-methyl–2-butene and 2,3-dimethyl–2-butene

“…Employed in this work, theoretical methods and computational procedures are the same as those used in our earlier works; 11,12 thus, only a brief description is provided here.…”

Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5-18 eV) electron interactions with DNA

“…With an identical probability for the distribution of bases in the DNA, n s for each base is 2.34 × 10 13 cm −2 , while its value for the sugar and phosphate groups is 9.36 × 10 13 cm −2 , ε i and σ i are mainly obtained from available EEL spectra; these have been measured by HREELS for the DNA bases, and tetrahydrofuran (THF) and phosphoric acid, as analogues of the sugar and phosphate groups in the DNA backbone, respectively. 21,36,37 For electron energies where such experimental data were not available, [38][39][40][41][42] The ε i and σ i were extracted from theoretical data. EEL spectra have been obtained from a single electron collision regime.…”

Interaction of low-energy electrons with the pyrimidine bases and nucleosides of DNA

“…However, electron-transmission studies on the nucleobases by Gallup, Burrow, and co-workers 15,34 have revealed the energies and widths of low-energy resonances, which they have assigned as valence shape resonances associated with the vacant * orbitals. Cross section calculations have generally relied on one-electron models [35][36][37][38] and have not yielded resonance positions in good agreement with experiment. 15,34,36,38,39 In three recent papers, we have reported electron collision cross sections computed from first principles for various nucleic-acid constituents, including the RNA base uracil, 40 the purine bases and nucleosides together with the purine nucleotide deoxyadenosine 5Ј-monophosphate, 41 and the backbone sugar deoxyribose as well as its 5Ј phosphate ester.…”