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Schatz GC, Wodtke AM, Yang X. Spiers Memorial Lecture: New directions in molecular scattering. Faraday Discuss 2024; 251:9-62. [PMID: 38764350 DOI: 10.1039/d4fd00015c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
The field of molecular scattering is reviewed as it pertains to gas-gas as well as gas-surface chemical reaction dynamics. We emphasize the importance of collaboration of experiment and theory, from which new directions of research are being pursued on increasingly complex problems. We review both experimental and theoretical advances that provide the modern toolbox available to molecular-scattering studies. We distinguish between two classes of work. The first involves simple systems and uses experiment to validate theory so that from the validated theory, one may learn far more than could ever be measured in the laboratory. The second class involves problems of great complexity that would be difficult or impossible to understand without a partnership of experiment and theory. Key topics covered in this review include crossed-beams reactive scattering and scattering at extremely low energies, where quantum effects dominate. They also include scattering from surfaces, reactive scattering and kinetics at surfaces, and scattering work done at liquid surfaces. The review closes with thoughts on future promising directions of research.
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Affiliation(s)
- George C Schatz
- Dept of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Alec M Wodtke
- Institute for Physical Chemistry, Georg August University, Goettingen, Germany
- Max Planck Institute for Multidisciplinary Natural Sciences, Goettingen, Germany.
- International Center for the Advanced Studies of Energy Conversion, Georg August University, Goettingen, Germany
| | - Xueming Yang
- Dalian Institute for Chemical Physics, Chinese Academy of Sciences, Dalian, China
- Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen, China
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2
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Plomp V, Wang XD, Kłos J, Dagdigian PJ, Lique F, Onvlee J, van de Meerakker SY. Imaging Resonance Effects in C + H 2 Collisions Using a Zeeman Decelerator. J Phys Chem Lett 2024; 15:4602-4611. [PMID: 38640083 PMCID: PMC11071073 DOI: 10.1021/acs.jpclett.3c03379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 04/05/2024] [Accepted: 04/05/2024] [Indexed: 04/21/2024]
Abstract
An intriguing phenomenon in molecular collisions is the occurrence of scattering resonances, which originate from bound and quasi-bound states supported by the interaction potential at low collision energies. The resonance effects in the scattering behavior are extraordinarily sensitive to the interaction potential, and their observation provides one of the most stringent tests for theoretical models. We present high-resolution measurements of state-resolved angular scattering distributions for inelastic collisions between Zeeman-decelerated C(3P1) atoms and para-H2 molecules at collision energies ranging from 77 cm-1 down to 0.5 cm-1. Rapid variations in the angular distributions were observed, which can be attributed to the consecutive reduction of contributing partial waves and effects of scattering resonances. The measurements showed excellent agreement with distributions predicted by ab initio quantum scattering calculations. However, discrepancies were found at specific collision energies, which most likely originate from an incorrectly predicted quasi-bound state. These observations provide exciting prospects for further high-precision and low-energy investigations of scattering processes that involve paramagnetic species.
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Affiliation(s)
- Vikram Plomp
- Radboud
University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Xu-Dong Wang
- Radboud
University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Jacek Kłos
- University
of Maryland, Department of Physics,
Joint Quantum Institute, College
Park, Maryland 20742, United States of America
| | - Paul J. Dagdigian
- Johns
Hopkins University, Department of Chemistry, Baltimore, Maryland 21218, United States
of America
| | - François Lique
- Université
de Rennes, Institut de Physique
de Rennes, 263 avenue
du Général Leclerc, Rennes CEDEX 35042, France
| | - Jolijn Onvlee
- Radboud
University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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3
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Wei J, Liu J, Sun X, Miao J, Fang D. Transport properties and ionicity in allyl-/alkylether-based ILs and their binary systems with acetonitrile as the potential electrolytes: Correlation with interactions and structures. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Plomp V, Wang XD, Lique F, Kłos J, Onvlee J, van de Meerakker SYT. High-Resolution Imaging of C + He Collisions using Zeeman Deceleration and Vacuum-Ultraviolet Detection. J Phys Chem Lett 2021; 12:12210-12217. [PMID: 34928163 PMCID: PMC8724800 DOI: 10.1021/acs.jpclett.1c03643] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/13/2021] [Indexed: 05/25/2023]
Abstract
High-resolution measurements of angular scattering distributions provide a sensitive test for theoretical descriptions of collision processes. Crossed beam experiments employing a decelerator and velocity map imaging have proven successful to probe collision cross sections with extraordinary resolution. However, a prerequisite to exploit these possibilities is the availability of a near-threshold state-selective ionization scheme to detect the collision products, which for many species is either absent or inefficient. We present the first implementation of recoil-free vacuum ultraviolet (VUV) based detection in scattering experiments involving a decelerator and velocity map imaging. This allowed for high-resolution measurements of state-resolved angular scattering distributions for inelastic collisions between Zeeman-decelerated carbon C(3P1) atoms and helium atoms. We fully resolved diffraction oscillations in the angular distributions, which showed excellent agreement with the distributions predicted by quantum scattering calculations. Our approach offers exciting prospects to investigate a large range of scattering processes with unprecedented precision.
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Affiliation(s)
- Vikram Plomp
- Radboud
University, Institute for Molecules and
Materials, Heijendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
| | - Xu-Dong Wang
- Radboud
University, Institute for Molecules and
Materials, Heijendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
| | - François Lique
- Université
de Rennes, Institut de Physique de Rennes, 263 avenue du Général
Leclerc, Rennes 35042 CEDEX, France
| | - Jacek Kłos
- University
of Maryland, Department of Physics, Joint
Quantum Institute, College Park, Maryland 20742, United States of America
| | - Jolijn Onvlee
- Radboud
University, Institute for Molecules and
Materials, Heijendaalseweg
135, 6525 AJ Nijmegen, The Netherlands
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5
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Jansen P, Merkt F. Manipulating beams of paramagnetic atoms and molecules using inhomogeneous magnetic fields. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 120-121:118-148. [PMID: 33198967 DOI: 10.1016/j.pnmrs.2020.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/07/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
We review methods to manipulate the motion of pulsed supersonic atomic and molecular beams using time-independent and -dependent inhomogeneous magnetic fields. In addition, we discuss current and possible future applications and research directions.
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Affiliation(s)
- Paul Jansen
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Frédéric Merkt
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
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6
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Toscano J, Lewandowski HJ, Heazlewood BR. Cold and controlled chemical reaction dynamics. Phys Chem Chem Phys 2020; 22:9180-9194. [DOI: 10.1039/d0cp00931h] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
State-to-state chemical reaction dynamics, with complete control over the reaction parameters, offers unparalleled insight into fundamental reactivity.
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Affiliation(s)
- Jutta Toscano
- JILA and the Department of Physics
- University of Colorado
- Boulder
- USA
| | | | - Brianna R. Heazlewood
- Physical and Theoretical Chemistry Laboratory (PTCL)
- Department of Chemistry
- University of Oxford
- Oxford
- UK
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7
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Walpole V, Heid CG, Jambrina PG, Aoiz FJ, Brouard M. Steric Effects in the Inelastic Scattering of NO(X) + Ar: Side-on Orientation. J Phys Chem A 2019; 123:8787-8806. [PMID: 31513425 DOI: 10.1021/acs.jpca.9b07264] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rotationally inelastic collisions of NO(X) with Ar, in which the NO bond-axis is oriented side-on (i.e., perpendicular) to the incoming collision partner, are investigated experimentally and theoretically. The NO(X) molecules are selected in the |j = 0.5, Ω = 0.5, ε = -1, f⟩ state prior to bond-axis orientation in a static electric field. The scattered NO products are then state selectively detected using velocity-map ion imaging. The experimental bond-axis orientation resolved differential cross sections and integral steric asymmetries are compared with quantum mechanical calculations, and are shown to be in good agreement. The strength of the orientation field is shown to affect the structure observed in the differential cross sections, and to some extent also the steric preference, depending on the ratio of the initial e and f Λ-doublets in the superposition determined by the orientation field. Classical and quantum calculations are compared and used to rationalize the structures observed in the differential cross sections. It is found that these structures are due to quantum mechanical interference effects, which differ for the two possible orientations of the NO molecule due to the anisotropy of the potential energy surface probed in the side-on orientation. Side-on collisions are shown to maximize and afford a high degree of control over the scattering intensity at small scattering angles (θ < 90°), while end-on collisions are predicted to dominate in the backward scattered region (θ > 90°).
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Affiliation(s)
- Victoria Walpole
- The Department of Chemistry , University of Oxford, Chemistry Research Laboratory , 12 Mansfield Road , Oxford OX1 3TA , U.K
| | - Cornelia G Heid
- The Department of Chemistry , University of Oxford, Chemistry Research Laboratory , 12 Mansfield Road , Oxford OX1 3TA , U.K
| | - Pablo G Jambrina
- Departamento de Química Física , Universidad de Salamanca , 37008 , Salamanca , Spain
| | - F Javier Aoiz
- Departamento de Química Física, Facultad de Química , Universidad Complutense , 28040 Madrid , Spain
| | - Mark Brouard
- The Department of Chemistry , University of Oxford, Chemistry Research Laboratory , 12 Mansfield Road , Oxford OX1 3TA , U.K
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Cremers T, Janssen N, Sweers E, van de Meerakker SYT. Design and construction of a multistage Zeeman decelerator for crossed molecular beams scattering experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:013104. [PMID: 30709220 DOI: 10.1063/1.5066062] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/13/2018] [Indexed: 06/09/2023]
Abstract
Zeeman deceleration is a relatively new technique used to obtain full control over the velocity of paramagnetic atoms or molecules in a molecular beam. We present a detailed description of a multistage Zeeman decelerator that has recently become operational in our laboratory [Cremers et al., Phys. Rev. A 98, 033406 (2018)] and that is specifically optimized for crossed molecular beams scattering experiments. The decelerator consists of an alternating array of 100 solenoids and 100 permanent hexapoles to guide or decelerate beams of paramagnetic atoms or molecules. The Zeeman decelerator features a modular design that is mechanically easy to extend to arbitrary length and allows for solenoid and hexapole elements that are convenient to replace. The solenoids and associated electronics are efficiently water cooled and allow the Zeeman decelerator to operate at repetition rates exceeding 10 Hz. We characterize the performance of the decelerator using various beams of metastable rare gas atoms. Imaging of the atoms that exit the Zeeman decelerator reveals the transverse focusing properties of the hexapole array in the Zeeman decelerator.
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Affiliation(s)
- Theo Cremers
- Institute for Molecules and Materials, Radboud University, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Niek Janssen
- Institute for Molecules and Materials, Radboud University, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Edwin Sweers
- Institute for Molecules and Materials, Radboud University, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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P. van der Poel AP, Bethlem HL. A detailed account of the measurements of cold collisions in a molecular synchrotron. EPJ TECHNIQUES AND INSTRUMENTATION 2018; 5:6. [PMID: 30997320 PMCID: PMC6434929 DOI: 10.1140/epjti/s40485-018-0048-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/21/2018] [Indexed: 06/09/2023]
Abstract
We have recently demonstrated a general and sensitive method to study low energy collisions that exploits the unique properties of a molecular synchrotron (Van der Poel et al., Phys Rev Lett 120:033402, 2018). In that work, the total cross section for ND3 + Ar collisions was determined from the rate at which ammonia molecules were lost from the synchrotron due to collisions with argon atoms in supersonic beams. This paper provides further details on the experiment. In particular, we derive the model that was used to extract the relative cross section from the loss rate, and present measurements to characterize the spatial and velocity distributions of the stored ammonia molecules and the supersonic argon beams.
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Affiliation(s)
- Aernout P. P. van der Poel
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, Amsterdam, The Netherlands
| | - Hendrick L. Bethlem
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, Amsterdam, The Netherlands
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Abstract
We demonstrate a method to probe cold and ultracold chemistry in a single molecular beam. The approach exploits beam slippage, the velocity difference of different species in the same beam, to establish the relative velocity. Average collision energies of 2.5 mK are achieved but with a spread of 100% or more. However, by implementing a dual-slit chopper that can separately fix the velocities of the two species at the interaction region, we achieve precise control over the relative velocity and narrow its spread. Relative velocities of 7-10 ± 1.1 m/s are achieved with an angular divergence less than 0.25°. In the present study, we observe l-changing collisions occurring between Xe Rydberg atoms and Xe ground state atoms at subKelvin temperatures. We show that in this case the collision energies are tunable between 200 to 450 mK with a root-mean-square deviation of ∼18%. Application of the method to other species and access to much lower energies is straightforward.
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Affiliation(s)
- Chandika Amarasinghe
- Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States
| | - Arthur G Suits
- Department of Chemistry, University of Missouri , Columbia, Missouri 65211, United States
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