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Mao Y, Yuan J, Yang Z, Chen M. Quantum dynamics studies of isotope effects in the Mg +(3p) + HD → MgH +/MgD + + D/H insertion reaction. Sci Rep 2020; 10:3410. [PMID: 32098984 PMCID: PMC7042225 DOI: 10.1038/s41598-020-60033-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 02/03/2020] [Indexed: 11/17/2022] Open
Abstract
The time-dependent wave packet quantum dynamics studies for the Mg+(3p) + HD → MgH+/MgD+ + D/H diabatic reaction are carried out for the first time on recently developed diabatic YHWCH potential energy surfaces [Phys. Chem. Chem. Phys., 2018, 20, 6638-6647]. The results of reaction probabilities and total integral cross sections show a dramatic preference to the formation of MgD+ over MgH+ owing to the insertion reaction mechanism in the title reaction. The MgD+/MgH+ branching ratio witnesses a monotonic decrease from 10.58 to 3.88 at collision energy range of 0.01 to 0.20 eV, and at the collision energy of 0.114 eV, it is close to the experimental value of 5. The rovibrational state-resolved ICSs of the two channels show the products MgD+ have higher vibrational excitation and hotter rotational state distributions. The opacity function P(J) suggests that the MgH+ + D channel and MgD+ + H channel are dominated by high-b and low-b collisions, respectively. Both forward and backward scattering peaks are found in the differential cross section curves, whereas the angle distributions of products are not strictly forward-backward symmetric because of the short lifetime of the complex in the reaction.
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Affiliation(s)
- Ye Mao
- Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, 116024, PR China
| | - Jiuchuang Yuan
- Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, 116024, PR China
| | - Zijiang Yang
- Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, 116024, PR China
| | - Maodu Chen
- Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian, 116024, PR China.
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Schmid PC, Greenberg J, Miller MI, Loeffler K, Lewandowski HJ. An ion trap time-of-flight mass spectrometer with high mass resolution for cold trapped ion experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:123107. [PMID: 29289207 DOI: 10.1063/1.4996911] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Trapping molecular ions that have been sympathetically cooled with laser-cooled atomic ions is a useful platform for exploring cold ion chemistry. We designed and characterized a new experimental apparatus for probing chemical reaction dynamics between molecular cations and neutral radicals at temperatures below 1 K. The ions are trapped in a linear quadrupole radio-frequency trap and sympathetically cooled by co-trapped, laser-cooled, atomic ions. The ion trap is coupled to a time-of-flight mass spectrometer to readily identify product ion species and to accurately determine trapped ion numbers. We discuss, and present in detail, the design of this ion trap time-of-flight mass spectrometer and the electronics required for driving the trap and mass spectrometer. Furthermore, we measure the performance of this system, which yields mass resolutions of m/Δm ≥ 1100 over a wide mass range, and discuss its relevance for future measurements in chemical reaction kinetics and dynamics.
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Affiliation(s)
- P C Schmid
- JILA and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - J Greenberg
- JILA and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - M I Miller
- JILA and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - K Loeffler
- JILA and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - H J Lewandowski
- JILA and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
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Hashemloo A, Dion CM. Quantum stability of an ion in a Paul trap revisited. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1313464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- A. Hashemloo
- Department of Physics, Umeå University , Umeå, Sweden
| | - C. M. Dion
- Department of Physics, Umeå University , Umeå, Sweden
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Hashemloo A, Dion CM. Rotational dynamics of a diatomic molecular ion in a Paul trap. J Chem Phys 2015; 143:204308. [PMID: 26627960 DOI: 10.1063/1.4936425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present models for a heteronuclear diatomic molecular ion in a linear Paul trap in a rigid-rotor approximation, one purely classical and the other where the center-of-mass motion is treated classically, while rotational motion is quantized. We study the rotational dynamics and their influence on the motion of the center-of-mass, in the presence of the coupling between the permanent dipole moment of the ion and the trapping electric field. We show that the presence of the permanent dipole moment affects the trajectory of the ion and that it departs from the Mathieu equation solution found for atomic ions. For the case of quantum rotations, we also evidence the effect of the above-mentioned coupling on the rotational states of the ion.
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Affiliation(s)
- A Hashemloo
- Department of Physics, Umeå University, SE-901 87 Umeå, Sweden
| | - C M Dion
- Department of Physics, Umeå University, SE-901 87 Umeå, Sweden
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Willitsch S. Coulomb-crystallised molecular ions in traps: methods, applications, prospects. INT REV PHYS CHEM 2012. [DOI: 10.1080/0144235x.2012.667221] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Bovino S, Tacconi M, Gianturco FA. Cold Chemistry with Ionic Partners: Quantum Features of HeH+(1Σ) with H(1S) at Ultralow Energies. J Phys Chem A 2011; 115:8197-203. [DOI: 10.1021/jp203113e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- S. Bovino
- Department of Chemistry, “Sapienza” University of Rome, P. le A. Moro 5, 00185 Rome, Italy
| | - M. Tacconi
- Department of Chemistry, “Sapienza” University of Rome, P. le A. Moro 5, 00185 Rome, Italy
| | - F. A. Gianturco
- Department of Chemistry, “Sapienza” University of Rome, P. le A. Moro 5, 00185 Rome, Italy
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Gingell AD, Bell MT, Oldham JM, Softley TP, Harvey JN. Cold chemistry with electronically excited Ca+ Coulomb crystals. J Chem Phys 2011; 133:194302. [PMID: 21090857 DOI: 10.1063/1.3505142] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Rate constants for chemical reactions of laser-cooled Ca(+) ions and neutral polar molecules (CH(3)F, CH(2)F(2), or CH(3)Cl) have been measured at low collision energies (<E(coll)>/k(B)=5-243 K). Low kinetic energy ensembles of (40)Ca(+) ions are prepared through Doppler laser cooling to form "Coulomb crystals" in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca(+) ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of (40)Ca(+) involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state ((2)S(1/2)) and the combined excited states ((2)D(3/2) and (2)P(1/2)) of (40)Ca(+). These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.
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Affiliation(s)
- Alexander D Gingell
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom
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Willitsch S, Bell MT, Gingell AD, Softley TP. Chemical applications of laser- and sympathetically-cooled ions in ion traps. Phys Chem Chem Phys 2008; 10:7200-10. [PMID: 19060963 DOI: 10.1039/b813408c] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ensembles of cold atomic and molecular ions in ion traps prepared at millikelvin temperatures by laser and sympathetic cooling have recently found considerable interest in both physics and chemistry. At very low temperatures the ions form ordered structures in the trap also known as "Coulomb crystals". Ion Coulomb crystals exhibit a range of intriguing properties which render them attractive systems for novel experiments in chemical dynamics, ultrahigh-resolution spectroscopy and quantum-information processing. In this article we review the methods used to prepare atomic and molecular ion Coulomb crystals and discuss some recent studies in mass spectrometry, low-temperature chemistry and precision spectroscopy to illustrate their scientific potential for chemical applications. Finally, we conclude with an outlook on outstanding challenges and prospective further developments in the field.
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Affiliation(s)
- Stefan Willitsch
- Department of Chemistry, University College London, 20 Gordon Street, London, UK WC1H 0AJ.
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Willitsch S, Bell MT, Gingell AD, Procter SR, Softley TP. Cold Reactive Collisions between laser-cooled ions and velocity-selected neutral molecules. PHYSICAL REVIEW LETTERS 2008; 100:043203. [PMID: 18352269 DOI: 10.1103/physrevlett.100.043203] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Indexed: 05/26/2023]
Abstract
We report a new experimental method to study reactive ion-molecule collisions at very low temperatures. A source of laser-cooled ions in a linear Paul trap has been combined with a quadrupole-guide velocity selector to investigate the reaction of Ca+ with CH3F at collision energies E[over](coll)/k(B)> or =1 K with single-particle sensitivity. The technique represents a general approach to study reactive collisions between ions and polar molecules over a wide temperature range down to the cold regime.
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Affiliation(s)
- Stefan Willitsch
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom.
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Peng WP, Cai Y, Chang HC. Optical detection methods for mass spectrometry of macroions. MASS SPECTROMETRY REVIEWS 2004; 23:443-465. [PMID: 15290710 DOI: 10.1002/mas.20002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Detection of macroions has been a challenge in the field of mass spectrometry. Conventional ionization-based detectors, relying on production and multiplication of secondary electrons, are restricted to detection for charged particles of m/z < 1 x 10(6). While both energy-sensitive and charge-sensitive detectors have been developed recently to overcome the limitation, they are not yet in common use. Photon-sensitive detectors are suggested to be an alternative, with which detection of macroions (or charged particles) by either elastic light scattering (ELS) or laser-induced fluorescence (LIF) has been possible. In this article, we provide a critical review on the developments of novel optical detection methods for mass spectrometry of macroions, including both micron-sized and nano-sized synthetic polymers as well as high-mass biomolecules. Design and development of new spectrometers making possible observations of the mass spectra of macroions with sizes in the range of 10-10(3) nm or masses in the range of 1-10(6) MDa are illustrated. The potential and promise of this optical approach toward macroion detection with high efficiency are discussed in practical aspects.
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Affiliation(s)
- Wen-Ping Peng
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106
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