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Michishio K, Chiari L, Tanaka F, Nagashima Y. Anisotropic Photodetachment of Positronium Negative Ions with Linearly Polarized Light. PHYSICAL REVIEW LETTERS 2024; 132:203001. [PMID: 38829062 DOI: 10.1103/physrevlett.132.203001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/25/2024] [Accepted: 04/18/2024] [Indexed: 06/05/2024]
Abstract
We report on the anisotropic photodetachment of positronium negative ions, followed by the dissociation into p-wave electrons and positronium atoms, with a linearly polarized laser beam. We have observed a strong recoil effect of the photoelectrons on the translation momentum of the dissociated positronium atoms. With polarization angle-resolved measurements, the asymmetry parameter of the photoemission angular distribution of the ions at a photon energy of 1.165 eV was determined to be 1.97±0.04(stat)±0.07(syst), in agreement with a theoretical prediction. The present method can be applied to explore the unrevealed dissociation dynamics of exotic particle systems and their manipulation with polarized light.
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Affiliation(s)
- Koji Michishio
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Luca Chiari
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
| | - Fumi Tanaka
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Yasuyuki Nagashima
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
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Wang Y, Pei SQ, Kar S, Ho YK. Autoionization decay and radiative decay for doubly excited 1Po resonance states in H− and Ps− ions. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Michishio K, Kuma S, Nagata Y, Chiari L, Iizuka T, Mikami R, Azuma T, Nagashima Y. Threshold Photodetachment Spectroscopy of the Positronium Negative Ion. PHYSICAL REVIEW LETTERS 2020; 125:063001. [PMID: 32845653 DOI: 10.1103/physrevlett.125.063001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
Threshold photodetachment spectroscopy of the positronium negative ion has been accomplished for the first time employing an efficient source of the ions and photodetachment techniques combined with a tunable optical parametric oscillator and amplifier laser. The photodetachment threshold, corresponding to the electron affinity of positronium (1^{3}S_{1}), was determined to be 326.88±0.09(stat)±0.10(syst) meV by laser photodetachment threshold measurements. This result is consistent with a variational calculation corrected for leading relativistic and quantum electrodynamical effects.
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Affiliation(s)
- Koji Michishio
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Susumu Kuma
- Atomic, Molecular and Optical Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Yugo Nagata
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Luca Chiari
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
| | - Taro Iizuka
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Riki Mikami
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
| | - Toshiyuki Azuma
- Atomic, Molecular and Optical Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Yasuyuki Nagashima
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
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Higgins MD, Greene CH, Kievsky A, Viviani M. Nonresonant Density of States Enhancement at Low Energies for Three or Four Neutrons. PHYSICAL REVIEW LETTERS 2020; 125:052501. [PMID: 32794850 DOI: 10.1103/physrevlett.125.052501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/26/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
The low energy systems of three or four neutrons are treated within the adiabatic hyperspherical framework, yielding an understanding of the low energy quantum states in terms of an adiabatic potential energy curve. The dominant low energy potential curve for each system, computed here using widely accepted nucleon-nucleon interactions with and without the inclusion of a three-nucleon force, shows no sign of a low energy resonance. However, both systems exhibit a low energy enhancement of the density of states, or of the Wigner-Smith time delay, which derives from long-range universal physics analogous to the Efimov effect. That enhancement could be relevant to understanding the low energy excess of correlated four-neutron ejection events observed experimentally in a nuclear reaction by Kisamori et al. [Phys. Rev. Lett. 116, 052501 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.052501].
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Affiliation(s)
- Michael D Higgins
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - Chris H Greene
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA and Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, Indiana 47907, USA
| | - A Kievsky
- Instituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, 56127 Pisa, Italy
| | - M Viviani
- Instituto Nazionale di Fisica Nucleare, Largo Pontecorvo 3, 56127 Pisa, Italy
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Abstract
When an incident particle on a target gets attached to the target, the cross-section at that energy could be much larger compared to those at other energies. This is a short-lived state and decays by emitting an electron. Such states can also be formed by the absorption of a photon. Such states are below the higher thresholds and are called autoionization states, doubly excited states, or Feshbach resonances. There is also a possibility of such states to form above the thresholds. Then they are called shape resonances. Resonances are important in the diagnostic of solar and astrophysical plasmas. Some methods of calculating the resonance parameters are described and resonance parameters occurring in various systems are given.
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Calculations of Resonance Parameters for the Doubly Excited 1P° States in Ps− Using Exponentially Correlated Wave Functions. ATOMS 2019. [DOI: 10.3390/atoms8010001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Recent observations on resonance states of the positronium negative ion (Ps−) in the laboratory created huge interest in terms of the calculation of the resonance parameters of the simple three-lepton system. We calculate the resonance parameters for the doubly excited 1P° states in Ps− using correlated exponential wave functions based on the complex-coordinate rotation method. The resonance energies and widths for the 1P° Feshbach resonance states in Ps− below the N = 2, 3, 4, 5 Ps thresholds are reported. The 1P° shape resonance above the N = 2, 4 Ps thresholds are also reported. Our predications are in agreement with the available results. Few Feshbach resonance parameters below the N = 4 and 5 Ps thresholds have been reported in the literature. Our predictions will provide useful information for future resonance experiments in Ps−.
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Moncada F, Pedraza-González L, Charry J, do N Varella MT, Reyes A. Covalent bonds in positron dihalides. Chem Sci 2019; 11:44-52. [PMID: 32953003 PMCID: PMC7472554 DOI: 10.1039/c9sc04433g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/24/2019] [Indexed: 11/21/2022] Open
Abstract
We report a computational study on homo- and heteronuclear e+[X–Y–] compounds formed by two halide anions (X–, Y– = F–, Cl–, Br–) and one positron.
We report a computational study on homo- and heteronuclear e+[X–Y–] compounds formed by two halide anions (X–, Y– = F–, Cl–, Br–) and one positron. Our results indicate the formation of energetically stable positronic molecules in all cases. Analysis of the electron and positron densities points out that the formation of positron covalent bonds underlies the stabilization of the otherwise repelling dihalides, revealing that positronic bonding can reach far beyond the previously addressed e+[H–H–] molecule [J. Charry, M. T. do N. Varella and A. Reyes, Angew. Chem. Int. Ed., 2018, 57, 8859–8864.]. To a significant extent, the properties of the positron dihalides are similar to those of the purely electronic analogs, e–[A+B+], molecular cations with isoelectronic atomic cores (A+, B+ = Na+, K+, Rb+) bound by one electron. The positron bonds in the e+[X–Y–] complexes are however stronger than those in the isoelectronic e–[A+B+] counterparts, as the former have shorter bond lengths and higher bond energies. While an energy decomposition analysis points out that both electronic and positronic bonds essentially arise from electrostatic interactions, the more stable positron bonds are partly due to the higher polarizabilities of the dihalide anions, and partly to more significant contributions from correlation and relaxation effects.
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Affiliation(s)
- Félix Moncada
- Department of Chemistry , Universidad Nacional de Colombia , Av. Cra 30 # 45-03 , Bogotá , Colombia .
| | - Laura Pedraza-González
- Department of Chemistry , Universidad Nacional de Colombia , Av. Cra 30 # 45-03 , Bogotá , Colombia .
| | - Jorge Charry
- Department of Chemistry , Universidad Nacional de Colombia , Av. Cra 30 # 45-03 , Bogotá , Colombia .
| | - Márcio T do N Varella
- Instituto de Física , Universidade de São Paulo , Rua do Matão 1731 , 05508-090 São Paulo , Brazil
| | - Andrés Reyes
- Department of Chemistry , Universidad Nacional de Colombia , Av. Cra 30 # 45-03 , Bogotá , Colombia .
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Critical Stability of the Negatively Charged Positronium-Like Ions with Yukawa Potentials and Varying Z. ATOMS 2019. [DOI: 10.3390/atoms7020053] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The question of stability of a given quantum system made up of charged particles is of fundamental interest in atomic, molecular, and nuclear physics. In this work, the stability for the negatively charged positronium (Ps)-like ions or the three-body system ( Z e + , e − , e − ) with Yukawa potentials is studied using correlated exponential wavefunctions based on the Ritz variational method. We obtained the critical screening parameter μ C as a function of the continuously varied nuclear charge Z , the critical nuclear charge Z C as a function of the screening parameter μ , and the ionization energies in terms of the screening parameter μ and Z . The critical nuclear charge for the bare Coulomb system ( Z e + , e − , e − ) obtained using 700-term correlated exponential wavefunctions is in accord with the reported results. The ionization energy, μ C , and Z C for the Yukawa system ( Z e + , e − , e − ) exhibit interesting behaviors. The present study describes the possible nonexistence of Borromean binding as well as Efimov states. The possible existence of quasi-bound resonances states for the negatively charged screened Ps-like ions is briefly discussed.
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Abstract
Lyman-α radiation ( 2 P → 1 S ) has been seen from astrophysical sources and the sun. The line shape of this transition has been measured recently in Ps atoms both inside and outside a porous silica target. In the photodetachment of Ps−, the residual Ps atom can be left in the 2P state instead of the 1S state giving rise to positronium Lyman radiation at 2432 A0. Photodetachment cross sections of Ps− have been calculated when the Ps atom is left in nP states, n being 2, 3, 4, 5, 6 and 7, using the asymptotic form of the bound-state wave function and a plane wave for the final state wave function, following the approach of Ohmura and Ohmura [Phys. Rev. 1960, 118, 154] in the photodetachment of H−.
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