Impact-parameter formulation for electron capture from molecular targets

Corchs, Silvia; Rivarola, R D; McGuire, J. H.

doi:10.1103/physreva.47.3937

Cited by 28 publications

(20 citation statements)

References 17 publications

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“…Thus each one of the electrons of the different molecular orbitals is promoted separately to a continuum state, whereas it is assumed that the rest of the target electrons remain in their initial states. The prior version of the CDW-EIS approximation, within the impact parameter approximation, is employed to describe the reaction [40].…”

Section: Theoretical Descriptionmentioning

confidence: 99%

Electron emission from bromouracil and uracil induced by protons and radiosensitization

et al. 2022

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Absolute double differential cross sections (DDCS) of electrons emitted from uracil and 5-bromouracil (BrU) in collisions with protons of energy 200 keV have been measured for various forward and backward emission angles over wide range of electron energies. The measured DDCS are compared with the continuum distorted wave-eikonal initial state (CDW-EIS) calculations. The optimized structure of the BrU was estimated along with the population analysis of all the occupied orbitals using a self-consistent field density. A comparison between the measured DDCS data for the two molecules show that the cross section of low energy electrons emitted from BrU is substantially larger than that for uracil. The BrU-to-uracil DDCS ratios obtained from the present measurements indicate an enhancement of the electron emission by a factor which is as large as 2.0 to 2.5. These electrons being the major agent for damaging the DNA/RNA of the malignant tissues, the present results are expected to provide an important input for the radiosensitization effect in hadron therapy. It is noteworthy to mention that the CDW-EIS calculations for Coulomb ionization cannot predict such enhancement. A large angular asymmetry is observed for uracil with a broad structure, which is absent in case of BrU.

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Section: Theoretical Descriptionmentioning

confidence: 99%

Electron emission from bromouracil and uracil induced by protons and radiosensitization

et al. 2022

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“…The dynamics of the process is described within the prior form of the continuum distorted wave-eikonal initial state (CDW-EIS) formalism. The straight line version of the impact parameter approximation is used for the calculations [49].…”

Section: Theoretical Descriptionmentioning

confidence: 99%

Radiobiological effectiveness of iodouracil and the influence of atomic giant resonance

et al. 2020

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Hadron therapy combined with nanotechnology has been proposed as an elegant alternative for cancer treatment. Internal amplification of electron emission causing radiobiological effectiveness in nanoinserted biomolecules is of prime importance and has been measured here for the iodouracil molecule. Our experiment involves the measurement of angle and energy resolved double differential cross section (DDCS) of electron emission from iodouraciil and uracil (and also water) in collisions with fast C 6+ ions. The electron emission from iodouracil is substantially enhanced over that from uracil or water. The enhancement is much larger than the state-of-the-art model for Coulomb ionization based on the continuum distorted wave-eikonal initial state (CDW-EIS) approximation. The electron sensitizing factor (≈ 2.4) is in excellent agreement with the strand-breaking sensitizing factor (≈ 2.0) for metal nanoparticle embedded in a DNA. The enhancement is explained in terms of collective excitation of strongly correlated 4d electrons, known as atomic giant dipole resonance (GDR) in I atoms. The GDR contribution to the enhancement is derived, which is in excellent agreement with recent theoretical prediction, thereby providing conclusive experimental evidence of the crucial role of collective excitation in radio sensitization.

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“…In order to reduce the description of the collision to a single-electron process, we assume that the active electron is captured independently of the others from different initial orbitals by direct interaction with the projectile, whereas the passive ones are assumed to remain frozen during the collision. This approximation was first formulated with success to study electron capture for the case of atomic targets [39,40] and then extended to molecular targets [41]. This approximation has also been applied for electron ionization of atomic and molecular targets [42][43][44][45][46][47].…”

Section: Theoretical Modelmentioning

confidence: 99%

Single-Capture Cross Sections from Biological Molecules and Noble Gases by Bare Ion Impact

et al. 2019

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In this work, we report theoretical electron capture cross sections for single-electron removal from molecules of biological interest and noble gases by bare ion (H + and H e 2+) impact at energies ranging from 25 to 10,000 keV/amu. We use a distorted wave (DW) method where the intermediate continuum state of the active electron with the target ion has been taken into account. This method is developed within the framework of the independent electron model taking particular care of the representation of the bound continuum target states. Two different approximations have been considered for molecular targets: molecular representation of the bound-state target wavefunction and Bragg's additivity rule. The molecular orbital for targets are described within the framework of the complete neglect of differential overlap (CNDO) method based on the linear combination of atomic orbital (LCAO) approximation. Using the DW method, we have also calculated the K-, Land M-shell electron capture in collisions of bare ions with three noble gases He, Ne, and Ar respectively. Contributions from different molecular orbitals and different shells to the total cross sections (TCS) are studied. The preference of electron capture occurs in accordance as the binding energy of the active electron in molecular orbital and atomic shell. The maximum contributions to TCS for SC comes from the less bound electrons in repetitive orbitals, whereas the tightly bound electrons dominate the TCS at higher projectile energy regime. Variation of TCS with impact energy are compared with the available experimental observation and other theoretical findings. We find that the present theoretical method is satisfactory in both intermediate and high-energy region for molecules as well as noble gas targets to give reliable outcomes compared to other theoretical methods.

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Impact-parameter formulation for electron capture from molecular targets

Abstract: The impact-parameter representation is deduced from the formal scattering theory for electron capture by impact of bare ions on molecular targets. The role of the interactions between the projectile nucleus and the molecular nuclei is determined.PACS number(s): 34.70. +e

Cited by 28 publications

References 17 publications

Electron emission from bromouracil and uracil induced by protons and radiosensitization

Electron emission from bromouracil and uracil induced by protons and radiosensitization

Radiobiological effectiveness of iodouracil and the influence of atomic giant resonance

Single-Capture Cross Sections from Biological Molecules and Noble Gases by Bare Ion Impact

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