ORCID Profile
0000-0001-8224-7143
Current Organisation
Curtin University
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Publisher: MDPI AG
Date: 14-08-2023
Abstract: We extend the two-centre wave-packet convergent close-coupling approach to doubly differential ionisation in proton collisions with H2 to intermediate projectile energies. The results for the doubly differential cross section at projectile energies from 48 to 200 keV are presented as a function of the energy and angle of emitted electrons. We consider a wide range of emission angles from 10 to 160∘, and compare our results to experimental data, where available. Excellent agreement between the presented results and the experimental data was found, especially for emission angles less than 130∘. For very large backward emission angles our calculations tended to slightly overestimate the experimental data when energetic electrons are ejected and the doubly differential cross section is very small. This discrepancy may be due to the large uncertainties in the experimental data in this region and the model target description. Overall, the present results show significant improvement upon currently available theoretical results and provide a consistently accurate description of this process across a wide range of incident energies.
Publisher: American Physical Society (APS)
Date: 29-10-2021
Publisher: IOP Publishing
Date: 17-06-2020
Publisher: MDPI AG
Date: 10-11-2022
Abstract: The wave-packet convergent close-coupling approach is used to calculate integrated target excitation and ionisation cross sections in bare beryllium-ion collisions with the 2ℓm states of atomic hydrogen (where n, ℓ and m are the principal, orbital angular momentum and magnetic quantum numbers, respectively). The calculations are performed at representative projectile energies between 10 keV/u to 1 MeV/u. The calculated cross sections for collisions with H(2s) are compared with recent theoretical results. Generally, good agreement is observed for the n-partial excitation and total ionisation cross sections. However, a significant discrepancy is found for excitation into the dominant n=3 states at 100 keV/u, where the target excitation cross-section peaks. We also present the first calculations of the excitation and ionisation cross sections for Be4+ collisions with H(2p0) and H(2p±1).
Publisher: American Physical Society (APS)
Date: 24-11-2021
Publisher: American Physical Society (APS)
Date: 28-07-2022
Publisher: American Physical Society (APS)
Date: 04-08-2023
Publisher: IOP Publishing
Date: 20-05-2022
Abstract: Electron capture and ionisation in bare neon ion collisions with ground-state atomic hydrogen are modelled over the energy range from 1 to 2000 keV/u using the two-center semiclassical wave-packet convergent close-coupling method. The calculated total electron-capture cross section agrees very well with the molecular and atomic orbital close-coupling calculations at low and intermediate energies. Our results slightly overestimate the experimental results by Meyer et al [1985 Phys. Rev. A 32 3310], but underestimate the measurements by Panov et al [1983 Phys. Scr. T3 124] available only below 10 keV/u. At higher energies, where there are no measurements, the results also agree very well with the classical trajectory Monte-Carlo results. Partial n and nl -resolved electron-capture cross sections, important for fusion plasma diagnostics, have also been calculated for final states up to n = 10, where n and l are the final state principal and angular momentum quantum numbers, respectively. The results are generally in good agreement with the atomic calculations. However, due to the finer energy grid used, we are able to detect pronounced oscillations in the state-selective cross sections for n ⩾ 8 at energies below 10 keV/u. Our results for the total ionisation cross section are overall in good agreement with the latest classical trajectory Monte-Carlo results.
Publisher: American Physical Society (APS)
Date: 12-11-2020
Publisher: IOP Publishing
Date: 08-09-2021
Publisher: Springer Science and Business Media LLC
Date: 08-2023
DOI: 10.1140/EPJD/S10053-023-00743-0
Abstract: State-selective non-dissociative electron capture and ionisation cross sections are calculated for collisions between bare helium-ions and molecular hydrogen. The two-centre wave-packet convergent close-coupling approach is used and the hydrogen molecule is represented as an effective one-electron target. For the electron-capture cross section, our results are in good agreement with experimental measurements at energies above 100 keV/u. However, near the peak of the cross section, they are larger than the experimental data. The total ionisation cross section is also in good agreement with experiment, particularly at low and high energies. The results for the state-selective electron-capture cross section are generally in good agreement with the limited experimental measurements. However, we find that our results appear to consistently overestimate the experimental data for electron capture into the s states at intermediate energies. The present results are the first calculations capable of producing electron capture and ionisation cross sections over a wide incident energy range within a single unified theoretical framework.
Publisher: American Physical Society (APS)
Date: 21-12-2022
Publisher: American Physical Society (APS)
Date: 30-03-2023
Publisher: American Physical Society (APS)
Date: 14-09-2021
Publisher: MDPI AG
Date: 12-2022
Abstract: The two-center wave-packet convergent close-coupling method has been applied to model the processes of electron capture and ionisation in collisions of fully stripped neon and lithium ions with atomic hydrogen at projectile energies from 1 keV/u to 1 MeV/u. For the Ne10+ projectile, the resulting total electron-capture cross section lies between the two sets of experimental results available for system, which differ from each other significantly. For Li3+, our total electron-capture cross section agrees with the available experimental measurements by Shah et al. [J. Phys. B: At. Mol. Opt. Phys 11, L233 (1978)] and Seim et al. [J. Phys. B: At. Mol. Opt. Phys 14, 3475 (1981)], particularly at low and high energies. We also get good agreement with the existing theoretical works, particularly the atomic- and molecular-orbital close-coupling calculations. Our total ionisation cross section overestimates the experimental data by Shah et al. [J. Phys. B: At. Mol. Opt. Phys 15, 413 (1982)] at the peak, however we get good agreement with the other existing theoretical calculations at low and high energies.
Publisher: Springer Science and Business Media LLC
Date: 07-2023
DOI: 10.1140/EPJD/S10053-023-00713-6
Abstract: Using the two-centre wave-packet convergent close-coupling approach, we continue our study of the proton–helium collision system. This method uses a correlated two-electron wave function to describe the helium target and discretises the continuum using wave-packet pseudostates. The cross section differential in the electron-emission energy and emission angle is calculated for incident-projectile energies in the intermediate range from 70 to 300 keV, where coupling between various channels and electron–electron correlation effects are important. We also apply an alternative, simpler approach that reduces the target to an effective single-electron system. Overall, the present results from both methods agree well with the available experimental data. This positions both implementations of the two-centre wave-packet convergent close-coupling approach well to further study other doubly differential, as well as fully differential, cross sections of single ionisation in proton–helium collisions.
Publisher: Springer Science and Business Media LLC
Date: 02-2022
DOI: 10.1140/EPJD/S10053-022-00359-W
Abstract: The two-centre wave-packet convergent close-coupling approach to ion–atom collisions is extended to study proton collisions with molecular hydrogen including electron-capture channels. We use a model potential to represent the molecular target as an effective one-electron spherically symmetric system. This greatly simplifies the target structure, allowing us to use already existing code developed for ion collisions with single-electron targets. Calculated total cross sections for electron capture, single ionisation, and excitation processes generally agree well with experimental data and other theoretical calculations where available. However, the total electron capture cross section is found to overestimate the experimental data at low energies, while the total ionisation cross section is slightly underestimated. Additionally, we present state-resolved cross sections for capture into the 1s, 2 $$\\ell $$ ℓ , and 3 $$\\ell $$ ℓ states of the projectile where deviation between various previous calculations is substantial. Our results lead to overall improvement over previous theoretical studies although discrepancies with experiment are observed for 3p and 3d capture. We conclude that treating molecular hydrogen as an effective one-electron system within the two-centre coupled-channel approach to one-electron targets can give reasonably accurate total cross sections at intermediate and high energies, without the need for a complex and computationally demanding two-electron target representation.
Publisher: Springer Science and Business Media LLC
Date: 07-2022
DOI: 10.1140/EPJD/S10053-022-00442-2
Abstract: The recently developed two-centre wave-packet convergent close-coupling approach to proton collisions with molecular hydrogen is applied to calculate various singly differential cross sections. The approach is based on an effective one-electron description of the $${\\hbox {H}_2}$$ H 2 target. The angular differential cross sections for elastic scattering, total excitation and electron capture are presented. Furthermore, we calculate the singly differential ionisation cross sections as functions of the ejected-electron energy and angle, as well as projectile scattering angle. Good agreement with available experimental data is observed, providing improvement over previous theoretical investigations into the singly differential cross section for ionisation. Specific mechanisms responsible for electron emission in particular kinematic regimes are identified. It is concluded that the effective one-electron WP-CCC method is capable of providing reasonably accurate results on singly differential cross sections for all included interconnected processes taking place in $${\\hbox {p}}+{\\hbox {H}_2}$$ p + H 2 collisions.
Location: Australia
No related grants have been discovered for Corey T Plowman.