Calculated molecular double-differential cross-sections for ionisation under proton impact

“…where the atomic initial bound states of A and B are described by Roothan-Hartree-Fock (RHF) wavefunctions [50]. The other way to calculate the TCS is to take into account the molecular character of the target [51,52]. In this approximation, the different initial ground state molecular orbitals are assumed to be obtained by linear combination of atomic orbitals (LCAOs) whose coefficients are obtained from a population analysis [34,42,[53][54][55][56].…”

Section: The Target Description and Evaluation Of Transition Amplitudementioning

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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“…Ionization orbital energies were calculated with the GAUSSIAN 09 software at the restricted Hartree-Fock (RHF)/3-21G level of theory [53]. Besides that, the complete neglect of differential overlap (CNDO) approximation, similar to Senger et al [54], was used to calculate the total cross sections. The essential steps for both models are described in [34].…”

Section: Theoretical Modelsmentioning

confidence: 99%

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

et al. 2013

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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

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Calculated molecular double-differential cross-sections for ionisation under proton impact

Cited by 35 publications

References 48 publications

Ionization and Electron Capture Cross Sections for Single-Electron Removal from Biological Molecules by Swift Ion

Ionization and Electron Capture Cross Sections for Single-Electron Removal from Biological Molecules by Swift Ion

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

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

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