Cross sections for electron scattering from selected components of DNA and RNA

We present total, elastic, and inelastic cross sections for positron and electron scattering from tetrahydrofuran (THF) in the energy range between 1 and 5000 eV. Total cross sections (TCS), positronium formation cross sections, the summed inelastic integral cross sections (ICS) for electronic excitations and direct ionization, as well as elastic differential cross sections (DCS) at selected incident energies, have been measured for positron collisions with THF. The positron beam used to carry out these experiments had an energy resolution in the range 40-100 meV (full-width at half-maximum). We also present TCS results for positron and electron scattering from THF computed within the independent atom model using the screening corrected additivity rule approach. In addition, we calculated positron-impact elastic DCS and the sum over all inelastic ICS (except rotations and vibrations). While our integral and differential positron cross sections are the first of their kind, we compare our TCS with previous literature values for this species. We also provide a comparison between positron and electron-impact cross sections, in order to uncover any differences or similarities in the scattering dynamics with these two different projectiles.

Section: Elastic Differential Cross Sectionssupporting

confidence: 76%

Total, elastic, and inelastic cross sections for positron and electron collisions with tetrahydrofuran

Chiari

Anderson

Tattersall

et al. 2013

“…5 The binary-encounter-Bethe model, 6,7 which is a simplified version of the binary-encounter-dipole model, 6 is based on a combination of two theories by Mott 8 and by Bethe. 9 The method has been successfully employed for calculation of total electron-impact ionization cross sections of a variety of molecules, e.g., Refs.…”

Section: Beb Calculationsmentioning

confidence: 99%

Total dissociative electron attachment cross sections of selected amino acids

Scheer

Możejko

Gallup

et al. 2007

Total dissociative electron attachment cross sections are presented for the amino acids, glycine, alanine, proline, phenylalanine, and tryptophan, at energies below the first ionization energy. Cross section magnitudes were determined by observation of positive ion production and normalization to ionization cross sections calculated using the binary-encounter-Bethe method. The prominent 1.2 eV feature in the cross sections of the amino acids and the closely related HCOOH molecule is widely attributed to the attachment into the -COOH * orbital. The authors discuss evidence that direct attachment to the lowest * orbital may instead be responsible. A close correlation between the energies of the core-excited anion states of glycine, alanine, and proline and the ionization energies of the neutral molecules is found. A prominent feature in the total dissociative electron attachment cross section of these compounds is absent in previous studies using mass analysis, suggesting that the missing fragment is energetic H − .

“…2 At lower energies semiempirical models (often using chemical structure codes such as GAMESS and GAUSSIAN) have been used to calculate total inelastic electron impact cross sections for bio-organic compounds such as DNA and RNA bases and other DNA subunits. [12][13][14][15] Such methods can generate accurate data for electron energies above 100 eV, but are much less reliable at energies typical of LEEs. So far, the only experimentally derived, absolute LEE cross sections for inclusion in MC simulations are those measured for amorphous water ice.…”

Section: Introductionmentioning

confidence: 99%

Absolute cross section for loss of supercoiled topology induced by 10 eV electrons in highly uniform /DNA/1,3-diaminopropane films deposited on highly ordered pyrolitic graphite

Boulanouar

Fromm

Bass

et al. 2013

Self Cite

It was recently shown that the affinity of doubly charged, 1-3 diaminopropane (Dap 2+ ) for DNA permits the growth on highly ordered pyrolitic graphite (HOPG) substrates, of plasmid DNA films, of known uniform thickness [O. Boulanouar, A. Khatyr, G. Herlem, F. Palmino, L. Sanche, and M. Fromm, J. Phys. Chem. C 115, 21291-21298 (2011)]. Post-irradiation analysis by electrophoresis of such targets confirms that electron impact at 10 eV produces a maximum in the yield of single strand breaks that can be associated with the formation of a DNA − transient anion. Using a welladapted deterministic survival model for the variation of electron damage with fluence and film thickness, we have determined an absolute cross section for strand-break damage by 10 eV electrons and inelastic scattering attenuation length in DNA-Dap complex films.