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Gao Y, Cao T, Lin KZ, Guo DL, Zhang SF, Zhu XL, Zhang RT, Yan SC, Xu S, Zhao DM, Ma X. A high resolution reaction microscope with universal two-region time-focusing method. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:043302. [PMID: 38578918 DOI: 10.1063/5.0202775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 03/19/2024] [Indexed: 04/07/2024]
Abstract
This paper presents a novel reaction microscope designed for ion-atom collision investigations, established at the Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China. Its time-of-flight (TOF) spectrometer employs an innovative flight-time focusing method consisting of two acceleration regions, providing optimal time focusing conditions for charged fragments with diverse initial velocities. The TOF spectrometer's axis intentionally tilts by 12° relative to the ion beam direction, preventing potential obstructions from the TOF grid electrodes. The introduced focusing method allows for a flexible time-focusing TOF spectrometer design without restricting the length ratio of the two regions. In addition, this configuration in our case significantly suppresses noise on the recoil ion detector produced by residual gas in the ion beam trajectory, which is a considerable challenge in longitudinal spectrometers. In a test experiment on the single electron capture reaction involving 62.5 keV/u He2+ ions and a helium atomic beam, the recoil longitudinal momentum resolution achieved 0.068 atomic units. This novel configuration and successful test run show excellent precision for ion-atom collision studies.
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Affiliation(s)
- Y Gao
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - T Cao
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - K Z Lin
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - D L Guo
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - S F Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - X L Zhu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - R T Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - S C Yan
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - S Xu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - D M Zhao
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - X Ma
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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Kurz N, Fischer D, Pfeifer T, Dorn A. Reaction microscope for investigating ionization dynamics of weakly bound alkali dimers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:123202. [PMID: 34972432 DOI: 10.1063/5.0069506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/12/2021] [Indexed: 06/14/2023]
Abstract
We report on the implementation of a far-off-resonant, optical dipole force trap in a reaction microscope combined with a magneto-optical trap. Kinematically complete multi-photon ionization experiments were performed on optically trapped 6Li atoms and photo-associated 6Li2 molecules in their highest vibrational state. The apparatus allows us to distinguish different ionization mechanisms related to the presence of the IR field of the optical dipole trap that can occur during ionization of 6Li and 6Li2 in strong fields. In a series of proof-of-principle experiments, we detect weakly bound dimers via three-photon ionization with femtosecond pulses (τ = 30 fs) at a central wavelength of 780 nm and measure directly the momenta of the photoelectrons in coincidence with recoil ions.
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Affiliation(s)
- N Kurz
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - D Fischer
- Physics Department and LAMOR, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - T Pfeifer
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - A Dorn
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
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Sixt T, Guan J, Tsoukala A, Hofsäss S, Muthu-Arachchige T, Stienkemeier F, Dulitz K. Preparation of individual magnetic sub-levels of 4He(2 3S 1) in a supersonic beam using laser optical pumping and magnetic hexapole focusing. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:073203. [PMID: 34340447 DOI: 10.1063/5.0048323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
We compare two different experimental techniques for the magnetic-sub-level preparation of metastable 4He in the 23S1 level in a supersonic beam, namely, magnetic hexapole focusing and optical pumping by laser radiation. At a beam velocity of v = 830 m/s, we deduce from a comparison with a particle trajectory simulation that up to 99% of the metastable atoms are in the MJ″ = +1 sub-level after magnetic hexapole focusing. Using laser optical pumping via the 23P2-23S1 transition, we achieve a maximum efficiency of 94% ± 3% for the population of the MJ″ = +1 sub-level. For the first time, we show that laser optical pumping via the 23P1-23S1 transition can be used to selectively populate each of the three MJ″ sub-levels (MJ″ = -1, 0, +1). We also find that laser optical pumping leads to higher absolute atom numbers in specific MJ″ sub-levels than magnetic hexapole focusing.
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Affiliation(s)
- Tobias Sixt
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Jiwen Guan
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Alexandra Tsoukala
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Simon Hofsäss
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | | | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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Geppert P, Althön M, Fichtner D, Ott H. Diffusive-like redistribution in state-changing collisions between Rydberg atoms and ground state atoms. Nat Commun 2021; 12:3900. [PMID: 34162846 PMCID: PMC8222215 DOI: 10.1038/s41467-021-24146-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/01/2021] [Indexed: 12/03/2022] Open
Abstract
Exploring the dynamics of inelastic and reactive collisions on the quantum level is a fundamental goal in quantum chemistry. Such collisions are of particular importance in connection with Rydberg atoms in dense environments since they may considerably influence both the lifetime and the quantum state of the scattered Rydberg atoms. Here, we report on the study of state-changing collisions between Rydberg atoms and ground state atoms. We employ high-resolution momentum spectroscopy to identify the final states. In contrast to previous studies, we find that the outcome of such collisions is not limited to a single hydrogenic manifold. We observe a redistribution of population over a wide range of final states. We also find that even the decay to states with the same angular momentum quantum number as the initial state, but different principal quantum number is possible. We model the underlying physical process in the framework of a short-lived Rydberg quasi-molecular complex, where a charge exchange process gives rise to an oscillating electric field that causes transitions within the Rydberg manifold. The distribution of final states shows a diffusive-like behavior.
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Affiliation(s)
- Philipp Geppert
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Max Althön
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Daniel Fichtner
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Herwig Ott
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern, Germany.
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De Silva AHNC, Atri-Schuller D, Dubey S, Acharya BP, Romans KL, Foster K, Russ O, Compton K, Rischbieter C, Douguet N, Bartschat K, Fischer D. Using Circular Dichroism to Control Energy Transfer in Multiphoton Ionization. PHYSICAL REVIEW LETTERS 2021; 126:023201. [PMID: 33512178 DOI: 10.1103/physrevlett.126.023201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/26/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
Chirality causes symmetry breaks in a large variety of natural phenomena ranging from particle physics to biochemistry. We investigate one of the simplest conceivable chiral systems, a laser-excited, oriented, effective one-electron Li target. Prepared in a polarized p state with |m|=1 in an optical trap, the atoms are exposed to co- and counterrotating circularly polarized femtosecond laser pulses. For a field frequency near the excitation energy of the oriented initial state, a strong circular dichroism is observed and the photoelectron energies are significantly affected by the helicity-dependent Autler-Townes splitting. Besides its fundamental relevance, this system is suited to create spin-polarized electron pulses with a reversible switch on a femtosecond timescale at an energy resolution of a few meV.
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Affiliation(s)
- A H N C De Silva
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - D Atri-Schuller
- Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311, USA
| | - S Dubey
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - B P Acharya
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - K L Romans
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - K Foster
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - O Russ
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - K Compton
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - C Rischbieter
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
| | - N Douguet
- Department of Physics, Kennesaw State University, Kennesaw, Georgia 30144, USA
| | - K Bartschat
- Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311, USA
| | - D Fischer
- Physics Department and LAMOR, Missouri University of Science & Technology, Rolla, Missouri 65409, USA
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