1
|
Singh P, Bagul V, Champion C. Triply differential cross sections for electron and positron impact on methane. J Chem Phys 2023; 159:044302. [PMID: 37486430 DOI: 10.1063/5.0149844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 07/03/2023] [Indexed: 07/25/2023] Open
Abstract
We here report theoretical triply differential cross sections (TDCS) for 250 eV electron and positron impact ionization of the methane molecule calculated within the second-order distorted-wave Born approximation (DWBA2) for various momentum transfer conditions. The experimental data taken from Işık et al. [J. Phys. B: At., Mol. Opt. Phys. 49, 065203 (2016)] will be compared with the current theoretical predictions as well as molecular three body distorted wave (M3DW) approximation and generalized Sturmian function (GSF) theoretical models in a non-coplanar geometry. In the low analyzer scattering plane, the results obtained within the DWBA2 theory show better agreement with the experimental results compared to the GSF results. The M3DW results also exhibit agreement with the experimental results, in particular in the perpendicular plane geometry. Furthermore, significant differences between electron and positron TDCS were observed.
Collapse
Affiliation(s)
- Prithvi Singh
- Department of Physics, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur, Rajasthan 313601, India
| | - Vijay Bagul
- Department of Physics, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur, Rajasthan 313601, India
| | - Christophe Champion
- Centre d'Études Lasers et Applications (CELIA), Université de Bordeaux, 33400 Talence, France
| |
Collapse
|
2
|
Interference Effects in Fully Differential Ionization Cross Sections near the Velocity Matching in P + He Collisions. ATOMS 2022. [DOI: 10.3390/atoms10040119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We performed a fully differential experimental and theoretical study on ionization of He in intermediate-energy collisions with protons for a small projectile coherence length. Data were taken for an ejected electron energy corresponding to a speed close to the projectile speed (velocity matching). In the fully differential angular electron distributions, a pronounced double-peak structure, observed previously for a coherence length much larger than the atomic size, is much less pronounced in the current data. This observation is interpreted in terms of interference between first-and higher-order transition amplitudes. Although there is large quantitative disagreement between experiment and theory, the qualitative agreement supports this interpretation.
Collapse
|
3
|
Calculation of Electron Impact Single Ionization TDCS of Tungsten Atoms at 200, 500 and 1000 eV. ATOMS 2021. [DOI: 10.3390/atoms9020031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We report triple differential cross-sections (TDCSs) for the electron impact single ionization of tungsten atoms for the ionization taking place from the outer sub shells of tungsten atoms, viz. W (6s), W (5d), W (5p) and W (4f). The study of the electron-induced processes such as ionization, excitation, autoionization from tungsten and its charged states is strongly required to diagnose and model the fusion plasma in magnetic devices such as Tokamaks. Particularly, the cross-section data are important to understand the electron spectroscopy involved in the fusion plasma. In the present study, we report TDCS results for the ionization of W atoms at 200, 500 and 1000 eV projectile energy at different values of scattered electron angles. It was observed that the trends of TDCSs for W (5d) are significantly different from the trends of TDCSs for W (6s), W (5p) and W (4f). It was further observed that the TDCS for W atoms has sensitive dependence on value of momentum transfer and projectile energy.
Collapse
|
4
|
Differential Study of Projectile Coherence Effects on Double Capture Processes in p + Ar Collisions. ATOMS 2020. [DOI: 10.3390/atoms8020010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We have measured differential yields for double capture and double capture accompanied by ionization in 75 keV p + Ar collisions. Data were taken for two different transverse projectile coherence lengths. A small effect of the projectile coherence properties on the yields were found for double capture, but not for double capture plus ionization. The results suggest that multiple projectile–target interactions can lead to a significant weakening of projectile coherence effects.
Collapse
|
5
|
Ali E, Granados C, Sakaamini A, Harvey M, Ancarani LU, Murray AJ, Dogan M, Ning C, Colgan J, Madison D. Triple differential cross sections for electron-impact ionization of methane at intermediate energy. J Chem Phys 2019; 150:194302. [PMID: 31117797 DOI: 10.1063/1.5097670] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report an experimental and theoretical investigation of electron-impact single ionization of the highest occupied molecular orbital 1t2 and the next highest occupied molecular orbital 2a1 states of CH4 at an incident electron energy of 250 eV. Triple differential cross sections measured in two different laboratories were compared with results calculated within the molecular 3-body distorted wave and generalized Sturmian function theoretical models. For ionization of the 1t2 state, the binary peak was observed to have a single maximum near the momentum transfer direction that evolved into a double peak for increasing projectile scattering angles, as has been seen for ionization of atomic p-states. A detailed investigation of this evolution was performed. As expected because of its s-type character, for ionization of the 2a1 state, only a single binary peak was observed. Overall, good agreement was found between experiment and theory.
Collapse
Affiliation(s)
- Esam Ali
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - Carlos Granados
- Institut für Physik, Martin-Luther Universität Halle-Wittenberg, 06199 Halle(Saale), Germany
| | - Ahmad Sakaamini
- Photon Science Institute, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Matthew Harvey
- Photon Science Institute, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | | | - Andrew James Murray
- Photon Science Institute, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Mevlut Dogan
- Ecol Academy, Afyon Kocatepe Konutları, CK1, C3-030916 Afyon, Turkey
| | - Chuangang Ning
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing, China
| | - James Colgan
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Don Madison
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| |
Collapse
|
6
|
Singh P, Purohit G, Champion C, Sébilleau D, Madison D. Low energy electron and positron impact differential cross sections for the ionization of water molecules in the coplanar and perpendicular kinematics. J Chem Phys 2019; 150:054304. [PMID: 30736694 DOI: 10.1063/1.5088966] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report here triply differential cross sections (TDCSs) for 81 eV electron and positron-impact ionization of the combined (1b1 + 3a1) orbitals of the water molecule by using the second-order distorted wave Born approximation (DWBA2) for ejection electron and positron energies of 5 eV and 10 eV and different momentum transfer conditions. The electron-impact TDCS will be compared with the experimental data measured by Ren et al. [Phys. Rev. A 95, 022701 (2017)] and with the molecular 3-body distorted wave (M3DW) approximation results in the scattering plane as well as the perpendicular plane. The DWBA2 results are in better agreement with the experiment than the M3DW results for the scattering plane, and the M3DW results are somewhat better for the perpendicular plane. This observation is explained in terms of collision interactions. The electron and positron TDCSs are indistinguishable in the scattering plane. In the perpendicular plane, the positron results are similar in shape, but smaller in magnitude. However, the difference reduces with increasing projectile scattering angle and increasing ejected electron energy.
Collapse
Affiliation(s)
- P Singh
- Department of Physics, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur 313 601, India
| | - G Purohit
- Department of Physics, University College of Science, M.L.S. University, Udaipur 313001, India
| | - C Champion
- Centre d'Études Lasers et Applications (CELIA), Université Bordeaux, 33400 Talence, France
| | - D Sébilleau
- Departement Matériaux-Nanosciences Institut de Physique de Rennes 35042 Rennes, France
| | - D Madison
- Physics Department, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| |
Collapse
|
7
|
Purohit G, Kato D. Dependence of electron impact differential cross sections on the ionic charge to radius ratio for the Al 3+(2p) and Be 2+(1s) ions. J Chem Phys 2018; 148:084307. [PMID: 29495759 DOI: 10.1063/1.5016291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The triple differential cross sections (TDCSs) have been obtained for the electron impact ionization of ionic targets, Al3+(2p) and Be2+(1s), having nearly the same ratio of ionic charge to radius. In the first of this kind of study, the trends of cross sections have been found to match to a greater extent despite ionization taking place from the ionic targets having considerable difference in nuclear charges as well as the ionization taking place from different types of orbitals, p-orbital and s-orbital. The trends of TDCSs have not been found to agree considerably for the neutral Al (3p) and Be (2s) targets.
Collapse
Affiliation(s)
- G Purohit
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-Cho, Toki, Gifu 509-5292, Japan
| | - D Kato
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-Cho, Toki, Gifu 509-5292, Japan
| |
Collapse
|
8
|
Lamichhane BR, Arthanayaka T, Remolina J, Hasan A, Ciappina MF, Navarrete F, Barrachina RO, Lomsadze RA, Schulz M. Fully Differential Study of Capture with Vibrational Dissociation in p+H_{2} Collisions. PHYSICAL REVIEW LETTERS 2017; 119:083402. [PMID: 28952760 DOI: 10.1103/physrevlett.119.083402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Indexed: 06/07/2023]
Abstract
We have measured fully differential cross sections for electron capture in 75 keV p+H_{2} collisions with subsequent dissociation of the intermediate molecular H_{2}^{+} ion by vibrational excitation using different projectile coherence lengths. Data were obtained for two molecular orientations as a function of projectile scattering angle. Two types of interference, single- and molecular two-center interference, were identified. The two-center interference structure is phase shifted by π compared to what we expected. Furthermore, the presence of projectile coherence effects could be reconfirmed.
Collapse
Affiliation(s)
- B R Lamichhane
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - T Arthanayaka
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - J Remolina
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - A Hasan
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
- Department of Physics, UAE University, P.O. Box 15551, Al Ain, Abu Dhabi, United Arab Emirates
| | - M F Ciappina
- Institute of Physics of the ASCR, ELI-Beamlines, Na Slovance 2, 182 21 Prague, Czech Republic
| | - F Navarrete
- Centro Atómico Bariloche and Instituto Balseiro (Comisión Nacional de Energía Atómica and Universidad. Nacional. de Cuyo), Bariloche, 8400 Río Negro, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 2290 Caba, Argentina
| | - R O Barrachina
- Centro Atómico Bariloche and Instituto Balseiro (Comisión Nacional de Energía Atómica and Universidad. Nacional. de Cuyo), Bariloche, 8400 Río Negro, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 2290 Caba, Argentina
| | - R A Lomsadze
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
- Tbilisi State University, Tbilisi 0179, Georgia
| | - M Schulz
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| |
Collapse
|
9
|
Electron collisions with atoms, ions, molecules, and surfaces: Fundamental science empowering advances in technology. Proc Natl Acad Sci U S A 2016; 113:7026-34. [PMID: 27317740 DOI: 10.1073/pnas.1606132113] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electron collisions with atoms, ions, molecules, and surfaces are critically important to the understanding and modeling of low-temperature plasmas (LTPs), and so in the development of technologies based on LTPs. Recent progress in obtaining experimental benchmark data and the development of highly sophisticated computational methods is highlighted. With the cesium-based diode-pumped alkali laser and remote plasma etching of Si3N4 as examples, we demonstrate how accurate and comprehensive datasets for electron collisions enable complex modeling of plasma-using technologies that empower our high-technology-based society.
Collapse
|
10
|
|
11
|
Hubele R, LaForge A, Schulz M, Goullon J, Wang X, Najjari B, Ferreira N, Grieser M, de Jesus VLB, Moshammer R, Schneider K, Voitkiv AB, Fischer D. Polarization and interference effects in ionization of Li by ion impact. PHYSICAL REVIEW LETTERS 2013; 110:133201. [PMID: 23581316 DOI: 10.1103/physrevlett.110.133201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Indexed: 06/02/2023]
Abstract
We present initial-state selective fully differential cross sections for ionization of lithium by 24 MeV O8+ impact. The data for ionization from the 2s and 2p states look qualitatively different from each other and from 1s ionization of He. For ionization from the 2p state, to which in our study the m(L)=-1 substate predominantly contributes, we observe orientational dichroism and for 2s ionization pronounced interference which we trace back to the nodal structure of the initial-state wave function.
Collapse
Affiliation(s)
- R Hubele
- Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Schneider K, Schulz M, Wang X, Kelkar A, Grieser M, Krantz C, Ullrich J, Moshammer R, Fischer D. Role of projectile coherence in close heavy ion-atom collisions. PHYSICAL REVIEW LETTERS 2013; 110:113201. [PMID: 25166529 DOI: 10.1103/physrevlett.110.113201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Indexed: 06/03/2023]
Abstract
We have measured fully differential cross sections for single ionization and transfer ionization (TI) in 16 MeV O(7+)+He collisions. The impact parameters mostly contributing to single ionization are about an order of magnitude larger than for TI. Therefore, the projectile beam was much more coherent for the latter compared to the former process. The measured data suggest that, as a result, TI is significantly affected by interference effects which are not present in single ionization.
Collapse
Affiliation(s)
- K Schneider
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany and Extreme Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, D-64291 Darmstadt, Germany
| | - M Schulz
- Physics Department and LAMOR, Missouri University of Science and Technology, Rolla, Missouri 65409, USA and Institut für Kernphysik, Universität Frankfurt, Max-von-Laue Strasse 1, D-60438 Frankfurt, Germany
| | - X Wang
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany and Shanghai EBIT Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433, China
| | - A Kelkar
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany and Extreme Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, D-64291 Darmstadt, Germany
| | - M Grieser
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
| | - C Krantz
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
| | - J Ullrich
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany and Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany
| | - R Moshammer
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
| | - D Fischer
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
| |
Collapse
|
13
|
Gasaneo G, Ancarani L, Mitnik D, Randazzo J, Frapiccini A, Colavecchia F. Three-Body Coulomb Problems with Generalized Sturmian Functions. ADVANCES IN QUANTUM CHEMISTRY 2013. [DOI: 10.1016/b978-0-12-411544-6.00007-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
14
|
Ren X, Pflüger T, Xu S, Colgan J, Pindzola MS, Senftleben A, Ullrich J, Dorn A. Strong molecular alignment dependence of H2 electron impact ionization dynamics. PHYSICAL REVIEW LETTERS 2012; 109:123202. [PMID: 23005945 DOI: 10.1103/physrevlett.109.123202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Indexed: 06/01/2023]
Abstract
Low-energy (E(0) = 54 eV) electron impact single ionization of molecular hydrogen (H(2)) has been investigated as a function of molecular alignment in order to benchmark recent theoretical predictions [Colgan et al., Phys. Rev. Lett. 101, 233201 (2008) and Al-Hagan et al., Nature Phys. 5, 59 (2009)]. In contrast to any previous work, we observe distinct alignment dependence of the (e,2e) cross sections in the perpendicular plane in good overall agreement with results from time-dependent close-coupling calculations. The cross section behavior can be consistently explained by a rescattering of the ejected electron in the molecular potential resulting in an effective focusing along the molecular axis.
Collapse
Affiliation(s)
- X Ren
- Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Fischer D, Globig D, Goullon J, Grieser M, Hubele R, de Jesus VLB, Kelkar A, LaForge A, Lindenblatt H, Misra D, Najjari B, Schneider K, Schulz M, Sell M, Wang X. Ion-lithium collision dynamics studied with a laser-cooled in-ring target. PHYSICAL REVIEW LETTERS 2012; 109:113202. [PMID: 23005625 DOI: 10.1103/physrevlett.109.113202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Indexed: 06/01/2023]
Abstract
We present a novel experimental tool allowing for kinematically complete studies of break-up processes of laser-cooled atoms. This apparatus, the 'MOTReMi,' is a combination of a magneto-optical trap (MOT) and a reaction microscope (ReMi). Operated in an ion-storage ring, the new setup enables us to study the dynamics in swift ion-atom collisions on an unprecedented level of precision and detail. In the inaugural experiment on collisions with 1.5 MeV/amu O(8+)-Li the pure ionization of the valence electron as well as the ionization-excitation of the lithium target was investigated.
Collapse
Affiliation(s)
- D Fischer
- Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Xu S, Chaluvadi H, Ren X, Pflüger T, Senftleben A, Ning CG, Yan S, Zhang P, Yang J, Ma X, Ullrich J, Madison DH, Dorn A. Low energy (e, 2e) study from the 1t2 orbital of CH4. J Chem Phys 2012; 137:024301. [DOI: 10.1063/1.4732539] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
17
|
Colgan J, Pindzola MS. Angular distributions for the complete photofragmentation of the Li atom. PHYSICAL REVIEW LETTERS 2012; 108:053001. [PMID: 22400932 DOI: 10.1103/physrevlett.108.053001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Indexed: 05/31/2023]
Abstract
We explore the complete breakup of the Li atom after absorption of a single photon, the purest example of the so-called four-body Coulomb problem. The resulting strongly correlated three-electron continuum is investigated by calculating the angular distributions of the ionized electrons using advanced close-coupling techniques. We find that the distributions are dominated by the Coulomb interactions between the electrons, that multiple break-up processes can be identified, and that the complex dynamics of the fragmentation process are evident for most scattering geometries.
Collapse
Affiliation(s)
- J Colgan
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | |
Collapse
|
18
|
Schulz M, Wang X, Gundmundsson M, Schneider K, Kelkar A, Voitkiv AB, Najjari B, Schöffler M, Schmidt LPH, Dörner R, Ullrich J, Moshammer R, Fischer D. Strongly enhanced backward emission of electrons in transfer and ionization. PHYSICAL REVIEW LETTERS 2012; 108:043202. [PMID: 22400839 DOI: 10.1103/physrevlett.108.043202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Indexed: 05/31/2023]
Abstract
We studied three-dimensional angular distributions and longitudinal momentum spectra of electrons ejected in transfer plus ionization (TI), i.e., the ejection of one and the capture of a second target electron, for ion-helium collisions. We observe a pronounced structure strongly focused opposite to the projectile beam direction, which we associate with a new correlated TI mechanism proposed recently. This process contributes significantly to the total cross sections over a broad range of perturbations η, even at η as large as 0.5, where uncorrelated TI mechanisms were thought to be dominant.
Collapse
Affiliation(s)
- M Schulz
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Lindroth E, Argenti L. Atomic Resonance States and Their Role in Charge-Changing Processes. ADVANCES IN QUANTUM CHEMISTRY 2012. [DOI: 10.1016/b978-0-12-397009-1.00005-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
|
20
|
Zatsarinny O, Bartschat K. Nonperturbative treatment of ionization with excitation of helium by electron impact. PHYSICAL REVIEW LETTERS 2011; 107:023203. [PMID: 21797603 DOI: 10.1103/physrevlett.107.023203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Indexed: 05/31/2023]
Abstract
We present cross sections for electron-impact ionization and simultaneous ionization plus excitation of helium by electron impact. The results are obtained from a fully nonperturbative close-coupling formalism using our B-spline R-matrix approach. A large number of pseudostates in the expansion of the wave function represent the coupling to the ionization continuum. We obtain excellent agreement with the directly measured experimental cross section ratios (Bellm et al., Phys. Rev. A 75, 042704 (2007)) for ionization leaving the residual He⁺ ion in either the 1s ground state or the n = 2 (2s + 2p) excited states.
Collapse
Affiliation(s)
- Oleg Zatsarinny
- Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311, USA
| | | |
Collapse
|
21
|
Egodapitiya KN, Sharma S, Hasan A, Laforge AC, Madison DH, Moshammer R, Schulz M. Manipulating atomic fragmentation processes by controlling the projectile coherence. PHYSICAL REVIEW LETTERS 2011; 106:153202. [PMID: 21568555 DOI: 10.1103/physrevlett.106.153202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Indexed: 05/30/2023]
Abstract
We have measured the scattering angle dependence of cross sections for ionization in p+H2 collisions for a fixed projectile energy loss. Depending on the projectile coherence, interference due to indistinguishable diffraction of the projectile from the two atomic centers was either present or absent in the data. This shows that, due to the fundamentals of quantum mechanics, the preparation of the beam must be included in theoretical calculations. The results have far-reaching implications on formal atomic scattering theory because this critical aspect has been overlooked for several decades.
Collapse
Affiliation(s)
- K N Egodapitiya
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | | | | | | | | | | | | |
Collapse
|
22
|
Bradley JA, Seidler GT, Cooper G, Vos M, Hitchcock AP, Sorini AP, Schlimmer C, Nagle KP. Comparative study of the valence electronic excitations of N2 by inelastic x-ray and electron scattering. PHYSICAL REVIEW LETTERS 2010; 105:053202. [PMID: 20867914 DOI: 10.1103/physrevlett.105.053202] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/23/2010] [Indexed: 05/29/2023]
Abstract
Bound-state, valence electronic excitation spectra of N2 are probed by nonresonant inelastic x-ray and electron scattering. Within usual theoretical treatments, dynamical structure factors derived from the two probes should be identical. However, we find strong disagreements outside the dipole scattering limit, even at high probe energies. This suggests an unexpectedly important contribution from intramolecular multiple scattering of the probe electron from core electrons or the nucleus. These effects should grow progressively stronger as the atomic number of the target species increases.
Collapse
Affiliation(s)
- J A Bradley
- Physics Department, University of Washington, Seattle, Washington 98195, USA
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Ren X, Senftleben A, Pflüger T, Holzwarth M, Dorn A, Bartschat K, Bray I, Fursa DV, Colgan J, Pindzola MS, Al-Hagan O, Madison DH, Ullrich J. Three-dimensional cross sections for electron impact ionization of atoms and molecules. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/212/1/012003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
24
|
The Distorted-Wave Born Approach for Calculating Electron-Impact Ionization of Molecules. ACTA ACUST UNITED AC 2010. [DOI: 10.1155/2010/367180] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The distorted-wave Born approximation (DWBA) has been one of the most successful theoretical approaches for treating electron collisions with complicated atoms, and recently the DWBA has been successfully extended to treat electron-impact ionization of molecules. The purpose of this paper is to give an overview of that development and to provide a summary of the recent experimental and theoretical works examining low to intermediate energy electron-impact single ionization of molecules.
Collapse
|
25
|
Macek JH, Sternberg JB, Ovchinnikov SY, Briggs JS. Theory of deep minima in (e,2e) measurements of triply differential cross sections. PHYSICAL REVIEW LETTERS 2010; 104:033201. [PMID: 20366640 DOI: 10.1103/physrevlett.104.033201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Indexed: 05/29/2023]
Abstract
Deep minima in He(e,2e)He+ triply differential cross sections are traced to vortices in atomic wave functions. Such vortices have been predicted earlier, but the present calculations show that they have also been observed experimentally, although not recognized as vortices. Their observation in (e,2e) measurements shows that vortices play an important role in electron correlations related to the transfer of angular momentum between incident and ejected electrons. The vortices significantly extend the list of known features that summarize the general picture of electron correlations in impact ionization.
Collapse
Affiliation(s)
- J H Macek
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37496, USA
| | | | | | | |
Collapse
|
26
|
Gasaneo G, Mitnik DM, Frapiccini AL, Colavecchia FD, Randazzo JM. Theory of hyperspherical Sturmians for three-body reactions. J Phys Chem A 2009; 113:14573-82. [PMID: 19788257 DOI: 10.1021/jp9040869] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In this paper we present a theory to describe three-body reactions. Fragmentation processes are studied by means of the Schrodinger equation in hyperspherical coordinates. The three-body wave function is written as a sum of two terms. The first one defines the initial channel of the collision while the second one describes the scattered wave, which contains all the information about the collision process. The dynamics is ruled by an nonhomogeneous equation with a driven term related to the initial channel and to the three-body interactions. A basis set of functions with outgoing behavior at large values of hyperradius is introduced as products of angular and radial hyperspherical Sturmian functions. The scattered wave is expanded on this basis and the nonhomogeneous equation is transformed into an algebraic problem that can be solved by standard matrix methods. To be able to deal with general systems, discretization schemes are proposed to solve the angular and radial Sturmian equations. This procedure allows these discrete functions to be connected with the hyperquatization algorithm. Finally, the fragmentation transition amplitude is derived from the asymptotic limit of the scattered wave function.
Collapse
Affiliation(s)
- G Gasaneo
- Departamento de Física, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, 8000 Bahía Blanca, Buenos Aires, Argentina.
| | | | | | | | | |
Collapse
|
27
|
Laforge AC, Egodapitiya KN, Alexander JS, Hasan A, Ciappina MF, Khakoo MA, Schulz M. Three-body dynamics in single ionization of atomic hydrogen by 75 keV proton impact. PHYSICAL REVIEW LETTERS 2009; 103:053201. [PMID: 19792496 DOI: 10.1103/physrevlett.103.053201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Indexed: 05/28/2023]
Abstract
Doubly differential cross sections for single ionization of atomic hydrogen by 75 keV proton impact have been measured and calculated as a function of the projectile scattering angle and energy loss. This pure three-body collision system represents a fundamental test case for the study of the reaction dynamics in few-body systems. A comparison between theory and experiment reveals that three-body dynamics is important at all scattering angles and that an accurate description of the role of the projectile-target-nucleus interaction remains a major challenge to theory.
Collapse
Affiliation(s)
- A C Laforge
- Department of Physics and LAMOR, Missouri University of Science & Technology, Rolla, Missouri, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Filin A, Compton R, Romanov DA, Levis RJ. Impact-ionization cooling in laser-induced plasma filaments. PHYSICAL REVIEW LETTERS 2009; 102:155004. [PMID: 19518642 DOI: 10.1103/physrevlett.102.155004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Indexed: 05/27/2023]
Abstract
The ionization rates and subsequent electron dynamics for laser-induced plasma channels are measured for the noble gas series He, Ne, Ar, Kr, and Xe at 1.0 atm. The cw fluorescence emission increases superlinearly in the series from He to Xe in agreement with Ammosov-Delone-Krainov tunnel ionization calculations. The electron temperature after laser-induced plasma formation, measured by four-wave mixing, evolves from >20 eV to <1 eV kinetic energies with time constants ranging from 1 ns for He to 100 ps for Xe in agreement with an impact-ionization cooling model.
Collapse
Affiliation(s)
- A Filin
- Center for Advanced Photonics Research, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
| | | | | | | |
Collapse
|
29
|
Kadyrov AS, Bray I, Mukhamedzhanov AM, Stelbovics AT. Coulomb breakup problem. PHYSICAL REVIEW LETTERS 2008; 101:230405. [PMID: 19113531 DOI: 10.1103/physrevlett.101.230405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Indexed: 05/27/2023]
Abstract
We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the three-body wave functions. This formulation is valid for both short-range and Coulombic potentials. The post and prior forms of the breakup amplitude are derived without any reference to renormalization procedures.
Collapse
Affiliation(s)
- A S Kadyrov
- ARC Centre for Antimatter-Matter Studies, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia
| | | | | | | |
Collapse
|
30
|
Colgan J, Pindzola MS, Robicheaux F, Kaiser C, Murray AJ, Madison DH. Differential cross sections for the ionization of oriented H2 molecules by electron impact. PHYSICAL REVIEW LETTERS 2008; 101:233201. [PMID: 19113547 DOI: 10.1103/physrevlett.101.233201] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Indexed: 05/27/2023]
Abstract
A nonperturbative close-coupling technique is used to calculate differential cross sections for the electron-impact ionization of H2 at an energy of 35.4 eV. Our approach allows cross sections for any orientation of the molecule with respect to the incident electron beam to be analyzed. New features in the resulting cross sections are found compared with the case where the molecular orientation is averaged, and also with cross sections for He at equivalent electron kinematics. When averaged over all possible molecular orientations, good agreement is found with recent experimental results.
Collapse
Affiliation(s)
- J Colgan
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | | | | | | | | |
Collapse
|
31
|
Polynomial-time quantum algorithm for the simulation of chemical dynamics. Proc Natl Acad Sci U S A 2008; 105:18681-6. [PMID: 19033207 DOI: 10.1073/pnas.0808245105] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The computational cost of exact methods for quantum simulation using classical computers grows exponentially with system size. As a consequence, these techniques can be applied only to small systems. By contrast, we demonstrate that quantum computers could exactly simulate chemical reactions in polynomial time. Our algorithm uses the split-operator approach and explicitly simulates all electron-nuclear and interelectronic interactions in quadratic time. Surprisingly, this treatment is not only more accurate than the Born-Oppenheimer approximation but faster and more efficient as well, for all reactions with more than about four atoms. This is the case even though the entire electronic wave function is propagated on a grid with appropriately short time steps. Although the preparation and measurement of arbitrary states on a quantum computer is inefficient, here we demonstrate how to prepare states of chemical interest efficiently. We also show how to efficiently obtain chemically relevant observables, such as state-to-state transition probabilities and thermal reaction rates. Quantum computers using these techniques could outperform current classical computers with 100 qubits.
Collapse
|
32
|
Emmanouilidou A, Wang P, Rost JM. Initial state dependence in multielectron threshold ionization of atoms. PHYSICAL REVIEW LETTERS 2008; 100:063002. [PMID: 18352467 DOI: 10.1103/physrevlett.100.063002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Indexed: 05/26/2023]
Abstract
It is shown that the geometry of multielectron threshold ionization in atoms depends on the initial configuration of bound electrons. The reason for this behavior is found in the stability properties of the classical fixed point of the equations of motion for multiple threshold fragmentation. Specifically for three-electron breakup, apart from the symmetric triangular configuration also a breakup of lower symmetry in the form of a T shape can occur, as we demonstrate by calculating triple photoionization for the lithium ground and first excited states. We predict the electron breakup geometry for threshold fragmentation experiments.
Collapse
|
33
|
Hu SX. Three-body recombination of atomic ions with slow electrons. PHYSICAL REVIEW LETTERS 2007; 98:133201. [PMID: 17501198 DOI: 10.1103/physrevlett.98.133201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Indexed: 05/15/2023]
Abstract
Using the time-dependent wave-packets method, we have quantum mechanically investigated the three-body recombination process for electron energies varying from 10 to 0.01 eV. The classical "bottleneck" prediction on the probable population was confirmed by our S-wave quantum calculations for electron kinetic energies (K(E)) as low as 0.1 eV. But for K(E)<0.1 eV, the quantum three-body recombination tends to populate lower n levels than the classical theory predicted. We also find that, in the same n level, the recombination tends to populate higher angular-momentum states with K(E) decreasing. These results may shed light on the intrinsic dynamics of both ultracold plasmas and frozen Rydberg gases.
Collapse
Affiliation(s)
- S X Hu
- Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, NY 14623, USA
| |
Collapse
|
34
|
Foster M, Peacher JL, Schulz M, Madison DH, Chen Z, Walters HRJ. Unexpected higher-order effects in charged particle impact ionization at high energies. PHYSICAL REVIEW LETTERS 2006; 97:093202. [PMID: 17026360 DOI: 10.1103/physrevlett.97.093202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Indexed: 05/12/2023]
Abstract
Most of the experimental and theoretical studies of electron-impact ionization of atoms, referred to as (e, 2e), have concentrated on the scattering plane. The assumption has been that all the important physical effects will be observable in the scattering plane. However, very recently it has been shown that, for C6+-helium ionization, experiment and theory are in nice agreement in the scattering plane and in very bad agreement out of the scattering plane. This lack of agreement between experiment and theory has been explained in terms of higher-order scattering effects between the projectile and target ion. We have examined electron-impact ionization of magnesium and have observed similar higher-order effects. The results of the electron-impact ionization of magnesium indicate the possible deficiencies in the calculation of fully differential cross sections in previous heavy particle ionization work.
Collapse
Affiliation(s)
- M Foster
- Physics Department and Laboratory for Atomic, Molecular, and Optical Research, University of Missouri-Rolla, 1870 Miner Circle, Rolla, Missouri 65409, USA
| | | | | | | | | | | |
Collapse
|
35
|
Dürr M, Dimopoulou C, Najjari B, Dorn A, Ullrich J. Three-dimensional images for electron-impact single ionization of He: complete and comprehensive (e, 2e) benchmark data. PHYSICAL REVIEW LETTERS 2006; 96:243202. [PMID: 16907237 DOI: 10.1103/physrevlett.96.243202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Indexed: 05/11/2023]
Abstract
Comprehensive fully differential cross sections for electron emission into all three spatial dimensions are presented for 1 keV and 102 eV electron-impact single ionization of helium using an advanced reaction microscope. Surprising out-of-plane contributions, traced back to an interference term in a perturbation expansion by comparison with ion-impact data, severely challenge theoretical models that accurately predict coplanar emission. The data represent the ultimate benchmark for recently developed exact theoretical descriptions of the most fundamental three-body quantum problems.
Collapse
Affiliation(s)
- M Dürr
- Max-Planck-Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | | | | | | | | |
Collapse
|
36
|
Bellm S, Lower J, Bartschat K. Electron-impact ionization and excitation of helium to the n=1-4 ionic states. PHYSICAL REVIEW LETTERS 2006; 96:223201. [PMID: 16803305 DOI: 10.1103/physrevlett.96.223201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Indexed: 05/10/2023]
Abstract
We present high-precision (e,2e) measurements and calculations for the e-He four-body Coulomb breakup problem. Cross-section ratios for ionization and excitation of the first three excited states of He+ relative to the ground state have been measured for incident energies between 112 and 319 eV. Comparing the data with predictions from a state-of-the-art hybrid distorted-wave+convergent R matrix with pseudostates (close coupling) approach shows that treating the projectile-target interaction at least to second order is crucial to obtain reasonable agreement between theory and experiment. Nevertheless, our benchmark studies reveal significant theoretical problems for the symmetric energy-sharing cases, thus indicating the need for further improvement.
Collapse
Affiliation(s)
- S Bellm
- AMPL, Research School for Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia
| | | | | |
Collapse
|
37
|
Williams JF, Bartlett PL, Stelbovics AT. Threshold electron-impact ionization mechanism for hydrogen atoms. PHYSICAL REVIEW LETTERS 2006; 96:123201. [PMID: 16605901 DOI: 10.1103/physrevlett.96.123201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Indexed: 05/08/2023]
Abstract
The near-threshold evolution of electron-impact ionization of hydrogen is revealed with measurements of the angular and energy correlations of the outgoing electrons down to 0.05 eV. The single-, double-, and triple-differential cross sections in the perpendicular plane are measured simultaneously using a dual wedge-and-strip detector on a single-toroidal energy analyzer, avoiding many experimental problems. The experimental and calculated data are in excellent agreement, within the experimental precision of +/-10%, and provide further evidence that the accurate solution of the Schrödinger equation provides a complete description of the reaction dynamics of near-threshold ionization.
Collapse
Affiliation(s)
- J F Williams
- Centre for Atomic, Molecular and Surface Physics, University of Western Australia, Perth 6009, Australia
| | | | | |
Collapse
|
38
|
Hu SX, Collins LA. Attosecond pump probe: exploring ultrafast electron motion inside an atom. PHYSICAL REVIEW LETTERS 2006; 96:073004. [PMID: 16606084 DOI: 10.1103/physrevlett.96.073004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Indexed: 05/08/2023]
Abstract
The attosecond pump probe, in close analogy to the standard femtosecond probing technique, has been proposed and theoretically demonstrated with its application to explore ultrafast electron motions inside atoms. We have performed realistic modeling for the full dynamics of both the femtosecond pumping and the attosecond probing processes. Our simulations have illustrated that an ultrashort oscillation period of 2.0 fs can be mapped out for a wave packet in low-lying excited states of the helium atom. This opens the prospect of a wealth of similar pump probe experiments to examine ultrafast electronic or atomic motions.
Collapse
Affiliation(s)
- S X Hu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | | |
Collapse
|
39
|
Vanroose W, Martín F, Rescigno TN, McCurdy CW. Complete Photo-Induced Breakup of the H
2
Molecule as a Probe of Molecular Electron Correlation. Science 2005; 310:1787-9. [PMID: 16357254 DOI: 10.1126/science.1120263] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Despite decades of progress in quantum mechanics, electron correlation effects are still only partially understood. Experiments in which both electrons are ejected from an oriented hydrogen molecule by absorption of a single photon have recently demonstrated a puzzling phenomenon: The ejection pattern of the electrons depends sensitively on the bond distance between the two nuclei as they vibrate in their ground state. Here, we report a complete numerical solution of the Schrödinger equation for the double photoionization of H2. The results suggest that the distribution of photoelectrons emitted from aligned molecules reflects electron correlation effects that are purely molecular in origin.
Collapse
Affiliation(s)
- Wim Vanroose
- Department of Computer Science, K.U. Leuven, Celestijnenlaan 200A, B-3001 Heverlee, Belgium
| | | | | | | |
Collapse
|
40
|
Sakhelashvili G, Dorn A, Höhr C, Ullrich J, Kheifets AS, Lower J, Bartschat K. Triple coincidence (e,gamma2e) experiment for simultaneous electron impact ionization excitation of helium. PHYSICAL REVIEW LETTERS 2005; 95:033201. [PMID: 16090741 DOI: 10.1103/physrevlett.95.033201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Indexed: 05/03/2023]
Abstract
Simultaneous ionization and excitation of helium atoms by 500 eV electron impact is observed by a triple coincidence of an ionized slow electron, the recoiling He+ ion, and the radiated vacuum ultraviolet photon (lambda< or =30.4 nm). Kinematically complete differential cross sections are presented for the He+(2p)2P final ionic state, demonstrating the feasibility of a quantum mechanically complete experiment. The experimental data are compared to predictions from state-of-the-art numerical calculations. For large momentum transfers, a first-order treatment of the projectile-target interaction can reproduce the experimental angular dependence, but a second-order treatment is required to obtain consistent magnitudes.
Collapse
Affiliation(s)
- G Sakhelashvili
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
41
|
On the Canonical Formulation of Electrodynamics and Wave Mechanics. ADVANCES IN QUANTUM CHEMISTRY 2005. [DOI: 10.1016/s0065-3276(05)49006-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
|
42
|
Bartlett PL, Stelbovics AT. Threshold behavior of e-H ionizing collisions. PHYSICAL REVIEW LETTERS 2004; 93:233201. [PMID: 15601156 DOI: 10.1103/physrevlett.93.233201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Indexed: 05/24/2023]
Abstract
We present accurate ab initio numerical solutions of the full Schrödinger equation for the electron-impact ionization of hydrogen near threshold using the propagating exterior complex scaling method. They provide strong support for the Wannier threshold law [Phys. Rev. 90, 817 (1953)], giving sigma proportional to E(1.122+/-0.015), and also give the energy dependence of the electrons' angular distribution as (pi-theta12) FWHM approximately 3.0E(1/4), in general agreement with classical and semiclassical predictions.
Collapse
Affiliation(s)
- Philip L Bartlett
- Centre for Atomic, Molecular and Surface Physics, Murdoch University, Perth 6150, Australia.
| | | |
Collapse
|
43
|
Weber T, Czasch AO, Jagutzki O, Müller AK, Mergel V, Kheifets A, Rotenberg E, Meigs G, Prior MH, Daveau S, Landers A, Cocke CL, Osipov T, Díez Muiño R, Schmidt-Böcking H, Dörner R. Complete photo-fragmentation of the deuterium molecule. Nature 2004; 431:437-40. [PMID: 15386008 DOI: 10.1038/nature02839] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Accepted: 07/13/2004] [Indexed: 11/09/2022]
Abstract
All properties of molecules--from binding and excitation energies to their geometry--are determined by the highly correlated initial-state wavefunction of the electrons and nuclei. Details of these correlations can be revealed by studying the break-up of these systems into their constituents. The fragmentation might be initiated by the absorption of a single photon, by collision with a charged particle or by exposure to a strong laser pulse: if the interaction causing the excitation is sufficiently understood, the fragmentation process can then be used as a tool to investigate the bound initial state. The interaction and resulting fragment motions therefore pose formidable challenges to quantum theory. Here we report the coincident measurement of the momenta of both nuclei and both electrons from the single-photon-induced fragmentation of the deuterium molecule. The results reveal that the correlated motion of the electrons is strongly dependent on the inter-nuclear separation in the molecular ground state at the instant of photon absorption.
Collapse
Affiliation(s)
- T Weber
- Institut für Kernphysik, Universität Frankfurt, D 60486 Frankfurt, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Colgan J, Pindzola MS, Robicheaux F. Lattice calculations of the photoionization of Li. PHYSICAL REVIEW LETTERS 2004; 93:053201. [PMID: 15323692 DOI: 10.1103/physrevlett.93.053201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2003] [Indexed: 05/24/2023]
Abstract
Calculations are presented for the double photoionization (with excitation) and triple photoionization of the Li atom. The motion of all three electrons is treated equally by solving the time-dependent Schrödinger equation in nine dimensions. A radial lattice is used to represent three of the nine dimensions, while a coupled channel expansion is used to represent the other six dimensions. Probabilities for photoionization are obtained by t--> infinity projection onto fully antisymmetric spatial and spin functions. Double photoionization cross sections for lithium leaving the ion in the 1s, 2s, and 2p states are presented. Good agreement is found with the measurements of Huang et al. [Phys. Rev. A 59, 3397 (1999)]] for the total double photoionization cross section and with the measurements of Wehlitz et al. [Phys. Rev. Lett. 81, 1813 (1998)]] for the triple photoionization cross section.
Collapse
Affiliation(s)
- J Colgan
- Department of Physics, Auburn University, Auburn, AL 36849, USA
| | | | | |
Collapse
|
45
|
Kadyrov AS, Mukhamedzhanov AM, Stelbovics AT, Bray I. Integral representation for the electron-atom ionization amplitude which is free of ambiguity and divergence problems. PHYSICAL REVIEW LETTERS 2003; 91:253202. [PMID: 14754114 DOI: 10.1103/physrevlett.91.253202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2003] [Indexed: 05/24/2023]
Abstract
It is shown that existing problems with the formal theory of ionization can be effectively resolved. An integral representation for the ionization amplitude free of ambiguity and divergence problems is given. Moreover, the ionization amplitude in the new formulation is shown directly to have an ideal form for practical calculations.
Collapse
Affiliation(s)
- A S Kadyrov
- Centre for Atomic, Molecular and Surface Physics, Division of Science and Engineering, Murdoch University, Perth 6150, Australia
| | | | | | | |
Collapse
|
46
|
Huang MT, Wong WW, Inokuti M, Southworth SH, Young L. Triple ionization of lithium by electron impact. PHYSICAL REVIEW LETTERS 2003; 90:163201. [PMID: 12731976 DOI: 10.1103/physrevlett.90.163201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2002] [Indexed: 05/24/2023]
Abstract
Ejection of the three electrons from lithium in a single electron collision has been observed for the first time. Triply charged lithium was observed in an ion time-of-flight spectrum following electron impact on a sample of ultracold, trapped lithium. The higher signal/background afforded by the trap environment made the observation of Li3+ possible. We measured the ratios of triple-to-double and double-to-single ionization at an impact energy of 1000 eV. The 3+/2+ ratio is approximately 0.001, a value 2 orders of magnitude lower than semiempirical predictions. We present a simple method that uses photoionization data combined with sum-rule analysis to predict the asymptotic charge-state ratios. The sum-rule predictions compare reasonably with experiment and shake calculations, but disagree sharply with the semiempirical estimates.
Collapse
Affiliation(s)
- M-T Huang
- Argonne National Laboratory, Argonne, Illinois 60439, USA
| | | | | | | | | |
Collapse
|
47
|
Schulz M, Moshammer R, Fischer D, Kollmus H, Madison DH, Jones S, Ullrich J. Three-dimensional imaging of atomic four-body processes. Nature 2003; 422:48-50. [PMID: 12621427 DOI: 10.1038/nature01415] [Citation(s) in RCA: 251] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Accepted: 12/16/2002] [Indexed: 11/09/2022]
Abstract
To understand the physical processes that occur in nature we need to obtain a solid concept about the 'fundamental' forces acting between pairs of elementary particles. It is also necessary to describe the temporal and spatial evolution of many mutually interacting particles under the influence of these forces. This latter step, known as the few-body problem, remains an important unsolved problem in physics. Experiments involving atomic collisions represent a useful testing ground for studying the few-body problem. For the single ionization of a helium atom by charged particle impact, kinematically complete experiments have been performed since 1969 (ref. 7). The theoretical analysis of such experiments was thought to yield a complete picture of the basic features of the collision process, at least for large collision energies. These conclusions are, however, almost exclusively based on studies of restricted electron-emission geometries. Here, we report three-dimensional images of the complete electron emission pattern for the single ionization of helium by the impact of C6+ ions of energy 100 MeV per a.m.u. (a four-body system) and observe features that have not been predicted by any published theoretical model. We propose a higher-order ionization mechanism, involving the interaction between the projectile and the target nucleus, to explain these features.
Collapse
Affiliation(s)
- M Schulz
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, D 69117 Heidelberg, Germany.
| | | | | | | | | | | | | |
Collapse
|
48
|
Bray I. Close-coupling approach to Coulomb three-body problems. PHYSICAL REVIEW LETTERS 2002; 89:273201. [PMID: 12513204 DOI: 10.1103/physrevlett.89.273201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2002] [Indexed: 05/24/2023]
Abstract
The convergent close-coupling method is shown to overcome the remaining discrepancies with experiment of electron-hydrogen ionization. Consequently, this method is able to calculate accurately the Coulomb three-body problems which include electron collisions with hydrogen and helium (within the frozen core model), and helium double photoionization at all incident energies and kinematical or geometrical arrangements of the outgoing electrons.
Collapse
Affiliation(s)
- Igor Bray
- Centre for Atomic, Molecular, and Surface Physics, School of Mathematical and Physical Sciences, Murdoch University, Murdoch 6150, Perth, Australia.
| |
Collapse
|
49
|
Parker GA, Walker RB, Kendrick BK, T Pack R. Accurate quantum calculations on three-body collisions in recombination and collision-induced dissociation. I. Converged probabilities for the H+Ne2 system. J Chem Phys 2002. [DOI: 10.1063/1.1503313] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
|
50
|
Kirchner T. Manipulating ion-atom collisions with coherent electromagnetic radiation. PHYSICAL REVIEW LETTERS 2002; 89:093203. [PMID: 12190399 DOI: 10.1103/physrevlett.89.093203] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2002] [Indexed: 05/23/2023]
Abstract
Laser-assisted ion-atom collisions are considered in terms of a nonperturbative quantum mechanical description of the electronic motion. It is shown for the system He(2+) - H at 2 keV/amu that the collision dynamics depend strongly on the initial phase of the laser field and the applied wavelength. Whereas electronic transitions are caused by the concurrent action of the field and the projectile ion at relatively low frequencies, they can be separated into modified collisional capture and field ionization events in the region above the one-photon ionization threshold.
Collapse
Affiliation(s)
- Tom Kirchner
- Department of Physics and Astronomy, York University, Toronto, Ontario, Canada M3J 1P3
| |
Collapse
|