Cross sections for positron and electron collisions with an analog of the purine nucleobases: Indole

Chiari, Luca; Zecca, Antonio; Blanco, F.; Garcı́a, Gustavo; Brunger, M. J.

doi:10.1103/physreva.91.012711

Cited by 9 publications

(11 citation statements)

References 73 publications

(95 reference statements)

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“…To evaluate in the DECS, Equation can be written as

\int_{0}^{π} \frac{d σ^{el}}{dθ} italicdΩ = s_{1} \int_{0}^{π} \frac{d σ_{1}^{el}}{dθ} italicdΩ + s_{1} \int_{0}^{π} \frac{d σ_{1}^{el}}{dθ} italicdΩ + \dots + s_{N} \int_{0}^{π} \frac{d σ_{N}^{el}}{dθ} italicdΩ,

where Ω = 2πsin θ d θ with θ = [0 − pi], the polar angle; coefficients s i depend only on the atomic total ECS, therefore,

\int_{0}^{π} \frac{d σ^{el}}{dθ} italicdΩ = \int_{0}^{π} ((), s_{1} \frac{d σ_{1}^{el}}{dθ} + s_{2} \frac{d σ_{2}^{el}}{dθ} + \dots + s_{N} \frac{d σ_{N}^{el}}{dθ}) italicdΩ .

The differential ECS is given as

\frac{d σ^{el}}{dθ} = s_{1} \frac{d σ_{1}^{el}}{dθ} + s_{2} \frac{d σ_{2}^{el}}{dθ} + \dots + s_{N} \frac{d σ_{N}^{el}}{dθ} .

We have checked that the integral of the left side of Equation leads exactly to the value of the total ECS given in the left side of Equation . In other studies, the DECS of the biomolecule is approximated by two separate contributions corresponding to incident charged particle suffering appreciable deviations and strong forward directionality; they are derived after some estimation on the relevance of ...…”

Section: Decs and Ecscontrasting

confidence: 91%

“…However, we are confident on the validity of the ECS for both charged particles even for energies as low as 10 eV; we have obtained very good agreement when comparing (not shown here in the present study) our ECS for electron on THF and PY with several experimental and theoretical data. On the other, our results differ from SCAR model cited in the literature even though we have used the same screening coefficients that take into account the geometrical positions of atoms forming the nucleobases. For positrons, we have shown relative differences as important as 250% for PY and THF and even at 10 keV; therefore, the total cross section will also increase allowing small mean free paths for the charged particle and hence an increase in the collision number.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…This correction is described by introduction of the screening effect of all atoms of the biomolecule. In contrast to the SCAR model, our model uses the same screening coefficients s i but differs substantially in the derivation of the DECS.…”

Section: Decs and Ecsmentioning

confidence: 99%

“…Positron scattering with biomolecules becomes important to investigate metabolic activity in the human body; its scattering measurements from biomolecules are not abundant. This motivated experimental and theoretical modeling to provide cross sections for the different possible interactions and in particular needed for Monte Carlo (MC) simulations. The main collisions are elastic and inelastic including ionizations and excitations.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of positron and electron elastic mean free path and diffusion angle on DNA nucleobases from 10 eV to 100 keV

Aouina

Chaoui

2018

Surface & Interface Analysis

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Funding informationDirection generale des enseignements et de la formation superieur, Grant/Award Number: CNEPRU ,project CNEPRU D01220140090 Positron and electron interaction collisions in living cells are efficiently simulated by Monte Carlo (MC) codes where huge data tables are needed. Present study provides detailed results of charged particles elastic interactions needed in MC on DNA nucleobases (adenine, thymine, cytosine and guanine, deoxyribose, and phosphoric acid). Indeed, electron and positron elastic cross sections, elastic mean free paths, and elastic angular distributions P(θ) are calculated from 10 eV to 100 keV using a corrected form of the independent atom method taking into account the geometry of the biomolecule. Our calculated results are compared with theoretical data available in the literature in absence of experimental data, in particular for positron. Moreover, our numerical results are presented in analytic format modeled to be used for fast sampling in the MC simulation of elastic collisions; particularly, we provide a useful analytic expression for sampling the elastic diffusion angle. For positron collisions on adenine, the relative error between numerical and analytic elastic diffusion angles is not exceeding 2% in the energy full range 10 eV to 100 keV. KEYWORDS angular distribution for elastic collision in DNA nucleobases, charged particles interaction with DNA nucleobases, cross section for Monte Carlo simulations, e − and e + ECS and EMFP from DNA nucleobases, fast sampling in elastic collisions

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“…To evaluate in the DECS, Equation can be written as

\int_{0}^{π} \frac{d σ^{el}}{dθ} italicdΩ = s_{1} \int_{0}^{π} \frac{d σ_{1}^{el}}{dθ} italicdΩ + s_{1} \int_{0}^{π} \frac{d σ_{1}^{el}}{dθ} italicdΩ + \dots + s_{N} \int_{0}^{π} \frac{d σ_{N}^{el}}{dθ} italicdΩ,

where Ω = 2πsin θ d θ with θ = [0 − pi], the polar angle; coefficients s i depend only on the atomic total ECS, therefore,

\int_{0}^{π} \frac{d σ^{el}}{dθ} italicdΩ = \int_{0}^{π} ((), s_{1} \frac{d σ_{1}^{el}}{dθ} + s_{2} \frac{d σ_{2}^{el}}{dθ} + \dots + s_{N} \frac{d σ_{N}^{el}}{dθ}) italicdΩ .

The differential ECS is given as

\frac{d σ^{el}}{dθ} = s_{1} \frac{d σ_{1}^{el}}{dθ} + s_{2} \frac{d σ_{2}^{el}}{dθ} + \dots + s_{N} \frac{d σ_{N}^{el}}{dθ} .

Section: Decs and Ecscontrasting

confidence: 91%

Section: Summary and Discussionmentioning

confidence: 99%

Section: Decs and Ecsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Simulation of positron and electron elastic mean free path and diffusion angle on DNA nucleobases from 10 eV to 100 keV

Aouina

Chaoui

2018

Surface & Interface Analysis

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“…The IAM-SCAR method was developed by Blanco and García (2009) and has been recently applied to numerous calculations of electron (see, e.g., Chiari et al, 2013a;2014a;and Sieradzka et al, 2014) and positron (e.g., Sanz et al, 2013b;Anderson et al, 2014;and Chiari et al, 2015) scattering cross sections from a variety of large polyatomic molecules and over an extensive impact energy range, typically from 1 to 1000 eV. Therefore, here we only briefly summarize the prominent aspects of this approach.…”

Section: Theory and Computational Detailsmentioning

confidence: 99%

Experimental and theoretical cross sections for positron scattering from the pentane isomers

Chiari

Zecca

Blanco

et al. 2016

The Journal of Chemical Physics

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Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present.

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Positron Collisions

2023

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Cross sections for positron and electron collisions with an analog of the purine nucleobases: Indole

Cited by 9 publications

References 73 publications

Simulation of positron and electron elastic mean free path and diffusion angle on DNA nucleobases from 10 eV to 100 keV

Simulation of positron and electron elastic mean free path and diffusion angle on DNA nucleobases from 10 eV to 100 keV

Experimental and theoretical cross sections for positron scattering from the pentane isomers

Positron Collisions

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