1
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Balakrishnan N, Jambrina PG, Croft JFE, Guo H, Aoiz FJ. Quantum stereodynamics of cold molecular collisions. Chem Commun (Camb) 2024; 60:1239-1256. [PMID: 38197484 DOI: 10.1039/d3cc04762h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Advances in quantum state preparations combined with molecular cooling and trapping technologies have enabled unprecedented control of molecular collision dynamics. This progress, achieved over the last two decades, has dramatically improved our understanding of molecular phenomena in the extreme quantum regime characterized by translational temperatures well below a kelvin. In this regime, collision outcomes are dominated by isolated partial waves, quantum threshold and quantum statistics effects, tiny energy splitting at the spin and hyperfine levels, and long-range forces. Collision outcomes are influenced not only by the quantum state preparation of the initial molecular states but also by the polarization of their rotational angular momentum, i.e., stereodynamics of molecular collisions. The Stark-induced adiabatic Raman passage technique developed in the last several years has become a versatile tool to study the stereodynamics of light molecular collisions in which alignment of the molecular bond axis relative to initial collision velocity can be fully controlled. Landmark experiments reported by Zare and coworkers have motivated new theoretical developments, including formalisms to describe four-vector correlations in molecular collisions that are revealed by the experiments. In this Feature article, we provide an overview of recent theoretical developments for the description of stereodynamics of cold molecular collisions and their implications to cold controlled chemistry.
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Affiliation(s)
- Naduvalath Balakrishnan
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154, USA.
| | - Pablo G Jambrina
- Departamento de Química Física, Universidad de Salamanca, Salamanca 37008, Spain
| | - James F E Croft
- The Dodd Walls Centre for Photonic and Quantum Technologies, New Zealand and Department of Physics, University of Otago, Dunedin, New Zealand
| | - Hua Guo
- Department of Chemistry and Chemical Biology, Center for Computational Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - F Javier Aoiz
- Departamento de Química Física, Universidad Complutense, Madrid 28040, Spain
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2
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Morita M, Kendrick BK, Kłos J, Kotochigova S, Brumer P, Tscherbul TV. Signatures of Non-universal Quantum Dynamics of Ultracold Chemical Reactions of Polar Alkali Dimer Molecules with Alkali Metal Atoms: Li( 2S) + NaLi( a3Σ +) → Na( 2S) + Li 2( a3Σ u+). J Phys Chem Lett 2023; 14:3413-3421. [PMID: 37001115 DOI: 10.1021/acs.jpclett.3c00159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Ultracold chemical reactions of weakly bound triplet-state alkali metal dimer molecules have recently attracted much experimental interest. We perform rigorous quantum scattering calculations with a new ab initio potential energy surface to explore the chemical reaction of spin-polarized NaLi(a3Σ+) and Li(2S) to form Li2(a3Σu+) and Na(2S). The reaction is exothermic and proceeds readily at ultralow temperatures. Significantly, we observe strong sensitivity of the total reaction rate to small variations of the three-body part of the Li2Na interaction at short range, which we attribute to a relatively small number of open Li2(a3Σu+) product channels populated in the reaction. This provides the first signature of highly non-universal dynamics seen in rigorous quantum reactive scattering calculations of an ultracold exothermic insertion reaction involving a polar alkali dimer molecule, opening up the possibility of probing microscopic interactions in atom+molecule collision complexes via ultracold reactive scattering experiments.
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Affiliation(s)
- Masato Morita
- Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Brian K Kendrick
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jacek Kłos
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, United States
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Svetlana Kotochigova
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Paul Brumer
- Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, United States
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3
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Yang D, Guo H, Xie D. Recent advances in quantum theory on ro-vibrationally inelastic scattering. Phys Chem Chem Phys 2023; 25:3577-3594. [PMID: 36602236 DOI: 10.1039/d2cp05069b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Molecular collisions are of fundamental importance in understanding intermolecular interaction and dynamics. Its importance is accentuated in cold and ultra-cold collisions because of the dominant quantum mechanical nature of the scattering. We review recent advances in the time-independent approach to quantum mechanical characterization of non-reactive scattering in tetratomic systems, which is ideally suited for large collisional de Broglie wavelengths characteristic in cold and ultracold conditions. We discuss quantum scattering algorithms between two diatoms and between a triatom and an atom and their implementation, as well as various approximate schemes. They not only enable the characterization of collision dynamics in realistic systems but also serve as benchmarks for developing more approximate methods.
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Affiliation(s)
- Dongzheng Yang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China. .,Hefei National Laboratory, Hefei 230088, China
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4
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Abstract
The amount of information that can be obtained from a scattering experiment depends upon the precision with which the quantum states are defined in the incoming channel. By precisely defining the incoming states and measuring the outgoing states in a scattering experiment, we set up the boundary condition for experimentally solving the Schrödinger equation. In this Perspective we discuss cold inelastic scattering experiments using the most theoretically tractable H2 and its isotopologues as the target. We prepare the target in a precisely defined rovibrational (v, j, m) quantum state using a special coherent optical technique called the Stark-induced adiabatic Raman passage (SARP). v and j represent the quantum numbers of the vibrational and rotational energy levels, and m refers to the projection of the rotational angular momentum vector j on a suitable quantization axis in the laboratory frame. Selection of the m quantum numbers defines the alignment of the molecular frame, which is necessary to probe the anisotropic interactions. For us to achieve the collision temperature in the range of a few degrees Kelvin, we co-expand the colliding partners in a mixed supersonic beam that is collimated to define a direction for the collision velocity. When the bond axis is aligned with respect to a well-defined collision velocity, SARP achieves stereodynamic control at the quantum scale. Through various examples of rotationally inelastic cold scattering experiments, we show how SARP coherently controls the dynamics of anisotropic interactions by preparing quantum superpositions of the orientational m states within a single rovibrational (v, j) energy state. A partial wave analysis, which has been developed for the cold scattering experiments, shows dominance of a resonant orbital that leaves its mark in the scattering angular distribution. These highly controlled cold collision experiments at the single partial wave limit allow the most direct comparison with the results of theoretical computations, necessary for accurate modeling of the molecular interaction potential.
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Affiliation(s)
- Nandini Mukherjee
- Department of Chemistry, Stanford University, Stanford, California94305, United States
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5
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Dyall KG, Tecmer P, Sunaga A. Diffuse Basis Functions for Relativistic s and d Block Gaussian Basis Sets. J Chem Theory Comput 2023; 19:198-210. [PMID: 36516433 DOI: 10.1021/acs.jctc.2c01050] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Diffuse s, p, and d functions have been optimized for use with previously reported relativistic basis sets for the s and d blocks of the periodic table. The functions were optimized on the 4:1 weighted average of the s2 and p2 configurations of the anion, with the d shell in the dn+1 configuration for the d blocks. Exponents were extrapolated for groups 2 and 12, which have unstable or weakly bound anions. The diffuse basis sets have been tested by application to calculations of electron affinities of the group 11 elements (Cu, Ag, and Au), double electron affinities of the group 11 monocations, and potential energy curves of Mg2 and Ca2 van der Waals dimers, as well as some response properties of the group 1 anions (Rb-, Cs-, and Fr-), the group 2 elements (Sr, Ba, and Ra), and RbLi, CsLi, and FrLi molecules.
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Affiliation(s)
- Kenneth G Dyall
- Dirac Solutions, 10527 NW Lost Park Drive, Portland, Oregon97229, United States
| | - Paweł Tecmer
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100Torun, Poland
| | - Ayaki Sunaga
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka590-0494, Japan.,Department of Physics, Graduate School of Science, Kyoto University, Kyoto606-8502, Japan
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6
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Jellali S, Habli H. Non-Relativistic Electronic-Structure Computation of Neutral and Cationic Systems [Fr 2, Fr-AEM + (AEM= Ca, Sr, Ba)]. J Phys Chem A 2022; 126:3613-3628. [PMID: 35670472 DOI: 10.1021/acs.jpca.1c10801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The experimental field of ultracold ion-atom mixtures including an alkali-metal atom and an alkaline-earth-metal ion as well as of homonuclear alkali dimers has paved the way for creating and manipulating the ultracold molecules. The present paper is focused on a study of molecules such us francium dimer and a comparative spectroscopic investigation of the cationic systems Fr-(Ca+, Sr+, Ba+). We adopt a computational scheme without spin-orbit coupling reposed on the full configuration interaction and semi-empirical pseudo-potential theory of the atomic cores Fr+, Ca2+, Sr2+, and Ba2+ with extended and optimized basis sets. We have determined the adiabatic potentials with their relative spectroscopic constants, the electric dipole moments and the vibrational levels spacings for the 1,3Σu,g+ and 1,3Σ+ electronic states for Fr2 and Fr-AEM+, respectively, correlated toward {Fr(7s) + Fr(7s, 7p, 6d, 8s, 8p)}, {Ca(4s2, 4s4p, 4s3d), Sr(5s2, 5s5p, 5s4d), Ba(6s2, 6s6p, 6s5d) + Fr+}, and {Ca+(4s, 3d), Sr+(5s, 4d), Ba+(6s, 5d) + Fr(7s, 7p)}. The accuracy and reliability of the current results are discussed by comparing with theoretical data available in the literature. The occurrence of some avoided crossings between the neighboring electronic states is leading to a charge or excitation transfer for atom-ion collisions in the diverse charge or excited states. The Σ+-Σ+ transitions are determined in order to evaluate the future radiative lifetimes of vibrational states serving the direct laser cooling.
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Affiliation(s)
- Soulef Jellali
- Faculté des Sciences de Monastir, Laboratoire de Physique Quantique et Statistique, Université de Monastir, Avenue de l'Environnement, Monastir 5019, Tunisie
| | - Héla Habli
- Faculté des Sciences de Monastir, Laboratoire de Physique Quantique et Statistique, Université de Monastir, Avenue de l'Environnement, Monastir 5019, Tunisie.,Institut Supérieur des Sciences Appliquées et de Technologie de Sousse, Université de Sousse, Rue ibn Khaldun, Cité Taffala, Sousse 4003, Tunisie
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7
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Moussa A, El-Kork N, Zeid I, Salem E, Korek M. Laser Cooling with an Intermediate State and Electronic Structure Studies of the Molecules CaCs and CaNa. ACS OMEGA 2022; 7:18577-18596. [PMID: 35694530 PMCID: PMC9178733 DOI: 10.1021/acsomega.2c01224] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/09/2022] [Indexed: 05/19/2023]
Abstract
The ground and excited electronic states of the diatomic molecules CaCs and CaNa have been investigated by implementing the ab initio CASSCF/(MRCI + Q) calculation. The potential energy curves of the doublet and quartet electronic low energy states in the representation 2s+1Λ(±) have been determined for the two considered molecules, in addition to the spectroscopic constants T e, ωe, B e, R e, and the values of the dipole moment μe and the dissociation energy D e. The determination of vibrational constants E v, B v, D v, and the turning points R min and R max up to the vibrational level v = 100 was possible with the use of the canonical functions schemes. Additionally, the transition and the static dipole moments curves, Einstein coefficients, the spontaneous radiative lifetime, the emission oscillator strength, and the Franck-Condon factors are computed. These calculations showed that the molecule CaCs is a good candidate for Doppler laser cooling with an intermediate state. A "four laser" cooling scheme is presented, along with the values of Doppler limit temperature T D = 55.9 μK and the recoil temperature T r = 132 nK. These results should provide a good reference for experimental spectroscopic and ultra-cold molecular physics studies.
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Affiliation(s)
- Amal Moussa
- Faculty
of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
| | - Nayla El-Kork
- Department
of Physics, Khalifa University, P.O. Box 127788, Abu Dhabi 51133, United Arab Emirates
- Space
and Planetary Science Center, Khalifa University, Abu Dhabi 51133, United Arab Emirates
| | - Israa Zeid
- Faculty
of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
| | - Ehab Salem
- Faculty
of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
| | - Mahmoud Korek
- Faculty
of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
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8
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Koyu S, Hermsmeier R, Tscherbul TV. Total angular momentum representation for state-to-state quantum scattering of cold molecules in a magnetic field. J Chem Phys 2022; 156:034112. [DOI: 10.1063/5.0074844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Suyesh Koyu
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
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9
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Theoretical Study of the FrLi Molecule: Computation of Adiabatic and Diabatic Potential Energy Curves, Spectroscopic Constants, Dipole Moment, Radiative Lifetime and Spectrum Absorption. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-021-05732-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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10
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Sáez-Rábanos V, Verdasco JE, Aoiz FJ, Herrero VJ. The F + HD(v = 0, 1; j = 0, 1) reactions: stereodynamical properties of orbiting resonances. Phys Chem Chem Phys 2021; 23:8002-8012. [PMID: 33480905 DOI: 10.1039/d0cp05425a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The excitation functions (reaction cross-section as a function of collision energy) of the F + HD(v = 0, 1; j = 0, 1) benchmark system have been calculated in the 0.01-6 meV collision energy interval using a time-independent hyperspherical quantum dynamics methodology. Special attention has been paid to orbiting resonances, which bring about detailed information on the three-atom interaction during the reactive encounter. The location of the resonances depends on the rovibrational state of the reactants HD(v,j), but is the same for the two product channels HF + D and DF + H, as expected for these resonances that are linked to the van der Waals well at the entrance. The resonance intensities depend both on the entrance and on the exit channels. The peak intensities for the HF + D channel are systematically larger than those for DF + H. Vibrational excitation leads to an increase of the peak intensity by more than an order of magnitude, but rotational excitation has a less drastic effect. It deceases the resonance intensity of the F + HD(v = 1) reaction, but increases somewhat that of F + HD(v = 0). Polarization of the rotational angular momentum with respect to the initial velocity reveals intrinsic directional preferences in the F + HD(v = 0, 1; j = 1) reactions that are manifested in the resonance patterns. The helicities (Ω = 0, Ω = ±1) possible for j = 1 contribute to the resonances, but that from Ω± 1 is, in general, dominant and in some cases exclusive. It corresponds to a preferential alignment of the HD internuclear axis perpendicular to the initial direction of approach and, thus, to side-on collisions. This work also shows that external preparation of the reactants, following the intrinsic preferences, would allow the enhancement or reduction of specific resonance features, and would be of great help for their eventual experimental detection.
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Affiliation(s)
- V Sáez-Rábanos
- Departamento de Sistemas y Recursos Naturales, E.T.S. de Ingeniería de Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, 28040, Madrid, Spain.
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11
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Abstract
We present a characterization of the ions’ translational energy distribution in a multipole ion trap. A linear mapping between the energy distribution of the trapped ions onto the ions’ time-of-flight (TOF) to a detector is demonstrated. For low ion temperatures, a deviation from linearity is observed and can be attributed to the emergence of multiple potential minima. The potential landscape of the trapped ions is modeled via the finite element method, also accounting for subtleties such as surface-charge accumulation. We demonstrate the validity of our thermometry method by simulating the energy distribution of the ion ensemble thermalized with buffer gas using a Molecular Dynamics (MD) simulation. A comparison between the energy distribution of trapped ions in different multipole trap configurations—i.e., with hyperbolic rods, cylindrical rods, and cylindrical wires—is provided. With these findings, one can map the temperature of the trapped ions down to the Kelvin regime using their TOF distributions. This enables future studies on sympathetic cooling and chemical reactions involving ions in multipole traps.
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12
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Pawlak M, Żuchowski PS, Moiseyev N, Jankowski P. Evidence of Nonrigidity Effects in the Description of Low-Energy Anisotropic Molecular Collisions of Hydrogen Molecules with Excited Metastable Helium Atoms. J Chem Theory Comput 2020; 16:2450-2459. [PMID: 32150402 PMCID: PMC7497643 DOI: 10.1021/acs.jctc.0c00183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Cold collisions serve
as a sensitive probe of the interaction potential.
In the recent study of Klein et al. (Nature Phys.2017, 13, 35–38), the one-parameter
scaling of the interaction potential was necessary to obtain agreement
between theoretical and observed patterns of the orbiting resonances
for excited metastable helium atoms colliding with hydrogen molecules.
Here, we show that the effect of nonrigidity of the H2 molecule
on the resonant structure, absent in the previous study, is critical
to predict the correct positions of the resonances in that case. We
have complemented the theoretical description of the interaction potential
and revised reaction rate coefficients by proper inclusion of the
flexibility of the molecule. The calculated reaction rate coefficients
are in remarkable agreement with the experimental data without empirical
adjustment of the interaction potential. We have shown that even state-of-the-art
calculations of the interaction energy cannot ensure agreement with
the experiment if such an important physical effect as flexibility
of the interacting molecule is neglected. Our findings about the significance
of the nonrigidity effects can be especially crucial in cold chemistry,
where the quantum nature of molecules is pronounced.
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Affiliation(s)
- Mariusz Pawlak
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
| | - Piotr S Żuchowski
- Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, 87-100 Toruń, Poland
| | - Nimrod Moiseyev
- Schulich Faculty of Chemistry and Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Piotr Jankowski
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
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13
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Jambrina PG, Croft JFE, Guo H, Brouard M, Balakrishnan N, Aoiz FJ. Stereodynamical Control of a Quantum Scattering Resonance in Cold Molecular Collisions. PHYSICAL REVIEW LETTERS 2019; 123:043401. [PMID: 31491255 DOI: 10.1103/physrevlett.123.043401] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Indexed: 06/10/2023]
Abstract
Cold collisions of light molecules are often dominated by a single partial wave resonance. For the rotational quenching of HD (v=1, j=2) by collisions with ground state para-H_{2}, the process is dominated by a single L=2 partial wave resonance centered around 0.1 K. Here, we show that this resonance can be switched on or off simply by appropriate alignment of the HD rotational angular momentum relative to the initial velocity vector, thereby enabling complete control of the collision outcome.
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Affiliation(s)
- Pablo G Jambrina
- Departamento de Química Física. Universidad de Salamanca, Salamanca 37008, Spain
| | - James F E Croft
- The Dodd-Walls Centre for Photonic and Quantum Technologies, Dunedin 9054, New Zealand and Department of Physics, University of Otago, Dunedin 9054, New Zealand
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Mark Brouard
- The Department of Chemistry, University of Oxford, The Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom
| | - Naduvalath Balakrishnan
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154, USA
| | - F Javier Aoiz
- Departamento de Química Física. Universidad Complutense. Madrid 28040, Spain
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14
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Sáez-Rábanos V, Verdasco JE, Herrero VJ. Orbiting resonances in the F + HD (v = 0, 1) reaction at very low collision energies. A quantum dynamical study. Phys Chem Chem Phys 2019; 21:15177-15186. [PMID: 31246200 PMCID: PMC6751073 DOI: 10.1039/c9cp02718a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-independent, fully converged, quantum dynamical calculations have been performed for the F + HD (v = 0, j = 0) and F + HD (v = 1, j = 0) reactions on an accurate potential energy surface down to collision energies of 0.01 meV. The two isotopic exit channels, HF + D and DF + H, have been investigated. The calculations reproduce satisfactorily the Feshbach resonance structures for collision energies between 10 and 40 meV, previously reported in the literature for the HF + D channel. Contrary to the results of a former literature work, vibrational excitation of HD is found to enhance reactivity in all cases down to the lowest collision energy investigated. Shape-type orbiting resonances are found for collision energies lower than 2 meV. The resonances appear as peaks in the reaction cross sections that are associated to specific values of the total angular momentum, J. In contrast with the Feshbach resonances at higher energies, the orbiting resonance structure, which is caused by the van der Waals well of the entrance channel, is identical for the HF + D and DF + H exit channels. The orbiting resonance peaks for F + HD (v = 0) are very small, but those for F + HD (v = 1) could be observed, in principle, with a combination of Raman pumping and merged beams methods.
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Affiliation(s)
- V Sáez-Rábanos
- Departamento de Sistemas y Recursos Naturales, E.T.S. de Ingeniería de Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
| | - J E Verdasco
- Departamento de Química Física, Facultad de Química, Universidad Complutense de Madrid (Unidad Asociada CSIC), 28040 Madrid, Spain.
| | - V J Herrero
- Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, 28006 Madrid, Spain.
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15
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De Fazio D, Aquilanti V, Cavalli S. Quantum Dynamics and Kinetics of the F + H 2 and F + D 2 Reactions at Low and Ultra-Low Temperatures. Front Chem 2019; 7:328. [PMID: 31157204 PMCID: PMC6527900 DOI: 10.3389/fchem.2019.00328] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/24/2019] [Indexed: 11/29/2022] Open
Abstract
Integral cross sections and rate constants for the prototypical chemical reactions of the fluorine atom with molecular hydrogen and deuterium have been calculated over a wide interval of collision energy and temperature ranging from the sub-thermal (50 K) down to the ultra-cold regimes (0.5 mK). Rigorous close coupling time-independent quantum reactive scattering calculations have been carried out on two potential energy surfaces, differing only at long-range in the reactants' channel. The results show that tunnel, resonance and virtual state effects enhance under-barrier reactivity giving rise to pronounced deviations from the Arrhenius law as temperature is lowered. Within the ultra-cold domain (below 1 mK), the reactivity is governed by virtual state effects and by tunneling through the reaction barrier; in the cold regime (1 mK–1 K), the shape resonances in the entrance channel of the potential energy surface make the quantum tunneling contribution larger so enhancing cross sections and rate constants by about one order of magnitude; at higher temperatures (above 10 K), the tunneling pathway enhanced by the constructive interference between two Feshbach resonances trapped in the reaction exit channel competes with the thermally activated mechanism, as the energy gets closer to the reaction barrier height. The results show that at low temperatures cross sections and rate constants are extremely sensitive to small changes in the long-range intermolecular interaction in the entrance channel of the potential energy surface, as well as to isotopic substitution.
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Affiliation(s)
- Dario De Fazio
- Istituto di Struttura della Materia, Consiglio Nazionale Delle Ricerche (CNR), Rome, Italy
| | - Vincenzo Aquilanti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
| | - Simonetta Cavalli
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
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16
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Mabrouk N, Zrafi W, Berriche H. Theoretical study of the LiNa molecule beyond the Born–Oppenheimer approximation: adiabatic and diabatic potential energy curves, radial coupling, adiabatic correction, dipole moments and vibrational levels. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1605098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- N. Mabrouk
- Laboratory of Interfaces and Advance Materials, Physics Department, Faculty of Science of Monastir, University of Monastir, Monastir, Tunisia
- Physics Department, College of Sciences, Northen Border University, Arar, Saudia Arabia
| | - Wissem Zrafi
- Laboratory of Interfaces and Advance Materials, Physics Department, Faculty of Science of Monastir, University of Monastir, Monastir, Tunisia
| | - H. Berriche
- Laboratory of Interfaces and Advance Materials, Physics Department, Faculty of Science of Monastir, University of Monastir, Monastir, Tunisia
- Mathematics and Natural Sciences Department, School of Arts and Sciences, American University of Ras Al Khaimah, Ras Al Khaimah, UAE
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17
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Passagem HF, Colín-Rodríguez R, Tallant J, Ventura da Silva PC, Bouloufa-Maafa N, Dulieu O, Marcassa LG. Continuous Loading of Ultracold Ground-State ^{85}Rb_{2} Molecules in a Dipole Trap Using a Single Light Beam. PHYSICAL REVIEW LETTERS 2019; 122:123401. [PMID: 30978081 DOI: 10.1103/physrevlett.122.123401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 02/10/2019] [Indexed: 06/09/2023]
Abstract
We have developed an approach to continuously load ultracold ^{85}Rb_{2} vibrational ground-state molecules into a crossed optical dipole trap from a magneto-optical trap. The technique relies on a single high-power light beam with a broad spectrum superimposed onto a narrow peak at an energy of about 9400 cm^{-1}. This single laser source performs all the required steps: the short-range photoassociation creating ground-state molecules after radiative emission, the cooling of the molecular vibrational population down to the lowest vibrational level v_{X}=0, and the optical trapping of these molecules. Furthermore, we probe by depletion spectroscopy and determine that 75% of the v_{X}=0 ground-state molecules are in the three lowest rotational levels J_{X}=0, 1, 2. The lifetime of the ultracold molecules in the optical dipole trap is limited to about 70 ms by off-resonant light scattering. The proposed technique opens perspectives for the formation of new molecular species in the ultracold domain, which are not yet accessible by well-established approaches.
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Affiliation(s)
- Henry Fernandes Passagem
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos, São Paulo, Brazil
| | - Ricardo Colín-Rodríguez
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos, São Paulo, Brazil
| | - Jonathan Tallant
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos, São Paulo, Brazil
| | - Paulo Cesar Ventura da Silva
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos, São Paulo, Brazil
| | - Nadia Bouloufa-Maafa
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, 91405 Orsay cedex, France
| | - Olivier Dulieu
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, 91405 Orsay cedex, France
| | - Luis Gustavo Marcassa
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos, São Paulo, Brazil
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18
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Morita M, Tscherbul TV. Restricted basis set coupled-channel calculations on atom-molecule collisions in magnetic fields. J Chem Phys 2019; 150:074110. [PMID: 30795668 DOI: 10.1063/1.5047063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rigorous coupled-channel quantum scattering calculations on molecular collisions in external fields are computationally demanding due to the need to account for a large number of coupled channels and multiple total angular momenta J of the collision complex. We show that by restricting the total angular momentum basis to include only the states with helicities K ≤ Kmax, it is possible to obtain accurate elastic and inelastic cross sections for low-temperature He + CaH, Li + CaH, and Li + SrOH collisions in the presence of an external magnetic field at a small fraction of the computational cost of the full coupled-channel calculations (where K is the projection of the molecular rotational angular momentum on the atom-diatom axis). The optimal size of the truncated helicity basis set depends on the mechanism of the inelastic process and on the magnitude of the external magnetic field, with the minimal basis set (Kmax = 0) producing quantitatively accurate results for, e.g., ultracold Li + CaH and Li + SrOH scattering at low magnetic fields, leading to nearly 90-fold gain in computational efficiency. Larger basis sets are required to accurately describe the resonance structure in the magnetic field dependence of Li + CaH and Li + SrOH inelastic cross sections in the few partial wave-regime as well as indirect spin relaxation in He + CaH collisions. Our calculations indicate that the resonance structure is due to an interplay of the spin-rotation and Coriolis couplings between the basis states of different K and the couplings between the rotational states of the same K induced by the anisotropy of the interaction potential.
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Affiliation(s)
- Masato Morita
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
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19
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Perreault WE, Mukherjee N, Zare RN. Supersonic beams of mixed gases: A method for studying cold collisions. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.02.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Huang J, Liu S, Zhang DH, Krems RV. Time-Dependent Wave Packet Dynamics Calculations of Cross Sections for Ultracold Scattering of Molecules. PHYSICAL REVIEW LETTERS 2018; 120:143401. [PMID: 29694154 DOI: 10.1103/physrevlett.120.143401] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 02/04/2018] [Indexed: 06/08/2023]
Abstract
Because the de Broglie wavelength of ultracold molecules is very large, the cross sections for collisions of molecules at ultracold temperatures are always computed by the time-independent quantum scattering approach. Here, we report the first accurate time-dependent wave packet dynamics calculation for reactive scattering of ultracold molecules. Wave packet dynamics calculations can be applied to molecular systems with more dimensions and provide real-time information on the process of bond rearrangement and/or energy exchange in molecular collisions. Our work thus makes possible the extension of rigorous quantum calculations of ultracold reaction properties to polyatomic molecules and adds a new powerful tool for the study of ultracold chemistry.
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Affiliation(s)
- Jiayu Huang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China and School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Shu Liu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China and School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China and School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Roman V Krems
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada
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21
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Yang QS, Li SC, Yu Y, Gao T. Theoretical Study of the Feasibility of Laser Cooling the 24Mg 35Cl Molecule Including Hyperfine Structure and Branching Ratios. J Phys Chem A 2018; 122:3021-3030. [PMID: 29498858 DOI: 10.1021/acs.jpca.7b11047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The possibility of laser cooling the 24Mg35Cl molecule is investigated using the electronic, rovibrational, and hyperfine structure. Twelve low-lying Λ-S electronic states of the 24Mg35Cl molecule have been calculated at the multireference configuration interaction level of theory. The spin-orbit coupling effects are taken into account in the electronic structure calculations. Spectroscopic constants agree well with previously obtained theoretical and experimental values. On the basis of the potential energy curves and transition dipole moments, the highly diagonally distributed Franck-Condon factors for the A2Π → X2Σ+ transition and short radiative lifetime of the A2Π state are determined. Then, employing a quantum effective Hamiltonian approach, we investigate the hyperfine manifolds of the X2Σ+ state and obtain the zero-field hyperfine spectrum with the errors relative to the experimental data not exceeding 8-20 kHz. Finally, we design a laser cooling scheme with one cooling main laser beam and two repumping laser beams with modulated sidebands, which is sufficient for the implementation of efficient laser slowing and cooling of the 24Mg35Cl molecule. Moreover, it is important to note that the dissociation energy (2.2593 eV) of the B2Σ+ state is obtained for the first time at the multireference configuration interaction level. We hope that this can provide a helpful reference for experimental observation.
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Affiliation(s)
- Quan-Shun Yang
- Institute of Atomic and Molecular Physics , Sichuan University , Chengdu 610065 , China.,College of Optoelectronic Technology , Chengdu University of Information Technology , Chengdu 610225 , China.,Key Laboratory of High Energy Density Physics and Technology of Ministry of Education , Sichuan University , Chengdu 610064 , China
| | - Shi-Chang Li
- Institute of Atomic and Molecular Physics , Sichuan University , Chengdu 610065 , China.,College of Optoelectronic Technology , Chengdu University of Information Technology , Chengdu 610225 , China.,Key Laboratory of High Energy Density Physics and Technology of Ministry of Education , Sichuan University , Chengdu 610064 , China
| | - You Yu
- Institute of Atomic and Molecular Physics , Sichuan University , Chengdu 610065 , China.,College of Optoelectronic Technology , Chengdu University of Information Technology , Chengdu 610225 , China.,Key Laboratory of High Energy Density Physics and Technology of Ministry of Education , Sichuan University , Chengdu 610064 , China
| | - Tao Gao
- Institute of Atomic and Molecular Physics , Sichuan University , Chengdu 610065 , China.,College of Optoelectronic Technology , Chengdu University of Information Technology , Chengdu 610225 , China.,Key Laboratory of High Energy Density Physics and Technology of Ministry of Education , Sichuan University , Chengdu 610064 , China
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22
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Gao Y, Wan M. Vibrational branching ratios and radiative lifetimes in the laser cooling of AlBr. Phys Chem Chem Phys 2018; 19:5519-5524. [PMID: 28165081 DOI: 10.1039/c6cp08181a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The feasibility of laser cooling of the AlBr molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the ground state X1Σ+ and the first two excited states (a3Π and A1Π) are calculated using the multi-reference configuration interaction plus Davidson corrections (MRCI+Q) method with the ACVQZ basis set; the spin-orbit coupling effects are also taken into account in electronic structure calculations at the MRCI level. Based on the acquired potential energy curves and transition dipole moments, highly diagonally distributed Franck-Condon factors (f00 = 0.9540, f11 = 0.8172) and vibrational branching ratios (R00 = 0.9708, R11 = 0.8420) for the transition are determined. Radiative lifetime calculations of the A1Π1 (ν' = 0-4) state are found to be short (9.16-11.48 ns) enough for rapid laser cooling. The proposed main cycling laser drives the transition at the wavelength λ00 = 279.19 nm. The vibrational branching loss ratios of the A1Π1 (ν') state to the intervening states a3Π0+ and a3Π1 are small (<5.2 × 10-6) enough to be negligible. The present theoretical results indicate that the AlBr molecule is a promising candidate for laser cooling.
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Affiliation(s)
- Yufeng Gao
- National Demonstration Center for Experimental Physics Education, College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China.
| | - Mingjie Wan
- Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007, China
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23
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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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24
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Bohn JL, Rey AM, Ye J. Cold molecules: Progress in quantum engineering of chemistry and quantum matter. Science 2017; 357:1002-1010. [PMID: 28883071 DOI: 10.1126/science.aam6299] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cooling atoms to ultralow temperatures has produced a wealth of opportunities in fundamental physics, precision metrology, and quantum science. The more recent application of sophisticated cooling techniques to molecules, which has been more challenging to implement owing to the complexity of molecular structures, has now opened the door to the longstanding goal of precisely controlling molecular internal and external degrees of freedom and the resulting interaction processes. This line of research can leverage fundamental insights into how molecules interact and evolve to enable the control of reaction chemistry and the design and realization of a range of advanced quantum materials.
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Affiliation(s)
- John L Bohn
- JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, CO 80309-0440, USA.
| | - Ana Maria Rey
- JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, CO 80309-0440, USA.
| | - Jun Ye
- JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, CO 80309-0440, USA.
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25
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El-Kork N, Abu El Kher N, Korjieh F, Chtay JA, Korek M. Electronic structure of the polar molecules XF (X: Be, Mg, Ca) with rovibrational and dipole moment calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 177:170-196. [PMID: 28183052 DOI: 10.1016/j.saa.2017.01.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 12/16/2016] [Accepted: 01/16/2017] [Indexed: 06/06/2023]
Abstract
A theoretical investigation for the feasibility of laser-cooling is performed through the calculation of accurate potential energy curves, static dipole moments, spectroscopic constants and rovibrational calculations for 24, 26 and 27 highly excited electronic states for BeF, CaF and MgF molecules respectively. In order to understand the electronic structure of their lowest lying electronic states and to learn the characteristic behavior of their chemical bonding, a high level of calculation is realized by using the complete active space self-consistent field (CASSCF) with multi-reference configuration interaction MRCI method including single and double excitations with Davidson correction (+Q) for the three considered molecules. The comparison between the values of the present work and those available in the literature for several electronic states shows a good agreement. Fifty new excited electronic states have been investigated, in the present work, for the first time for the three studied molecules.
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Affiliation(s)
- Nayla El-Kork
- Khalifa University, P.O. Box 57, Sharjah, United Arab Emirates
| | - Nariman Abu El Kher
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
| | - Farah Korjieh
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
| | - John Anwar Chtay
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon
| | - Mahmoud Korek
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020, Riad El Solh, Beirut 1107 2809, Lebanon.
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26
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Balakrishnan N. Perspective: Ultracold molecules and the dawn of cold controlled chemistry. J Chem Phys 2016; 145:150901. [DOI: 10.1063/1.4964096] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- N. Balakrishnan
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
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27
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Doçaj A, Wall ML, Mukherjee R, Hazzard KRA. Ultracold Nonreactive Molecules in an Optical Lattice: Connecting Chemistry to Many-Body Physics. PHYSICAL REVIEW LETTERS 2016; 116:135301. [PMID: 27081984 DOI: 10.1103/physrevlett.116.135301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 06/05/2023]
Abstract
We derive effective lattice models for ultracold bosonic or fermionic nonreactive molecules (NRMs) in an optical lattice, analogous to the Hubbard model that describes ultracold atoms in a lattice. In stark contrast to the Hubbard model, which is commonly assumed to accurately describe NRMs, we find that the single on-site interaction parameter U is replaced by a multichannel interaction, whose properties we elucidate. Because this arises from complex short-range collisional physics, it requires no dipolar interactions and thus occurs even in the absence of an electric field or for homonuclear molecules. We find a crossover between coherent few-channel models and fully incoherent single-channel models as the lattice depth is increased. We show that the effective model parameters can be determined in lattice modulation experiments, which, consequently, measure molecular collision dynamics with a vastly sharper energy resolution than experiments in a free-space ultracold gas.
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Affiliation(s)
- Andris Doçaj
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Michael L Wall
- JILA, NIST and University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Rick Mukherjee
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Kaden R A Hazzard
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
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28
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Simbotin I, Côté R. Jost function description of near threshold resonances for coupled-channel scattering. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Jankunas J, Jachymski K, Hapka M, Osterwalder A. Observation of orbiting resonances in He(3S1) + NH3Penning ionization. J Chem Phys 2015; 142:164305. [DOI: 10.1063/1.4919369] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Justin Jankunas
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | | | - Michał Hapka
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Andreas Osterwalder
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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30
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De Fazio D. The H + HeH(+) → He + H2(+) reaction from the ultra-cold regime to the three-body breakup: exact quantum mechanical integral cross sections and rate constants. Phys Chem Chem Phys 2015; 16:11662-72. [PMID: 24810283 DOI: 10.1039/c4cp00502c] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, we present a quantum mechanical scattering study of the title reaction from 1 mK to 2000 K. Total integral cross sections and thermal rate constants are compared with previous theoretical and experimental data and with simpler theoretical models to understand the range of validity of the approximations used in the previous studies. The obtained quantum reactive observables have been found to be nearly insensitive to the roto-vibrational energy of the reactants at high temperatures. More sensitive to the reactant's roto-vibrational energy are the data in the cold and ultra-cold regimes. The implications of the new data presented here in the early universe scenario are also discussed and analyzed.
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Affiliation(s)
- Dario De Fazio
- Istituto di Struttura della Materia - C.N.R., 00016 Roma, Italy.
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31
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32
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Cui J, Li Z, Krems RV. Collision lifetimes of polyatomic molecules at low temperatures: Benzene–benzene vs benzene–rare gas atom collisions. J Chem Phys 2014; 141:164315. [DOI: 10.1063/1.4898796] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jie Cui
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Zhiying Li
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Roman V. Krems
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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33
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Mabrouk N, Berriche H. Theoretical study of the CsNa molecule: adiabatic and diabatic potential energy and dipole moment. J Phys Chem A 2014; 118:8828-41. [PMID: 25058020 DOI: 10.1021/jp5043427] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The adiabatic and diabatic potential energy curves of the low-lying electronic states of the NaCs molecule dissociating into Na (3s, 3p) + Cs (6s, 6p, 5d, 7s, 7p, 6d, 8s, 4f) have been investigated. The molecular calculations are performed using an ab initio approach based on nonempirical pseudopotential, parametrized l-dependent polarization potentials and full configuration interaction calculations through the CIPCI quantum chemistry package. The derived spectroscopic constants (Re, De, Te, ωe, ωexe, and Be) of the ground state and lower excited states are compared with the available theoretical and experimental works. Moreover, accurate permanent and transition dipole moment have been determined as a function of the internuclear distance. The adiabatic permanent dipole moment for the first nine (1)Σ(+) electronic states have shown both ionic characters associated with electron transfer related to Cs(+)Na(-) and Cs(-)Na(+) arrangements. By a simple rotation, the diabatic permanent dipole moment is determined and has revealed a linear behavior, particularly at intermediate and large distances. Many peaks around the avoided crossing locations have been observed for the transition dipole moment between neighbor electronic states.
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Affiliation(s)
- N Mabrouk
- Laboratoire des Interfaces et Matériaux Avancés, Département de Physique, Faculté des Sciences de Monastir , Avenue de l'Environnement 5019 Monastir, Tunisia
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34
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Gao Y, Gao T. Ab initiostudy of ground and low-lying excited states of MgLi and MgLi+molecules with valence full configuration interaction and MRCI method. Mol Phys 2014. [DOI: 10.1080/00268976.2014.926030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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35
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Chen YM, Kuang XY, Sheng XW, Yan XZ. Calculating and modeling the exchange energies of homonuclear and heteronuclear alkali dimers based on the surface integral method. J Phys Chem A 2014; 118:592-7. [PMID: 24417373 DOI: 10.1021/jp406949x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The exchange energies of all homonuclear and heteronuclear alkali dimers are calculated based on the surface integral method. These results are generally in good agreement with both ab initio calculations and experimental results where available. It is also shown that the exchange energies could be fitted by an analytical expression of AR(b) exp(-cR). b and c can be calculated by two simple formulas that are only related to the ionization energies of the constituent atoms. A is the only parameter in this expression. More interestingly, it is found that the parameter A for the heteronuclear dimers could be approximated by a combining rule.
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Affiliation(s)
- Y M Chen
- The Institute of Atomic and Molecular Physics, Sichuan University , Chengdu, Sichuan 610065, China
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36
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Rennick CJ, Lam J, Doherty WG, Softley TP. Magnetic trapping of cold bromine atoms. PHYSICAL REVIEW LETTERS 2014; 112:023002. [PMID: 24484005 DOI: 10.1103/physrevlett.112.023002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Indexed: 06/03/2023]
Abstract
Magnetic trapping of bromine atoms at temperatures in the millikelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br2 molecules in a molecular beam. The lab-frame velocity of Br atoms is controlled by the wavelength and polarization of the photodissociation laser. Careful selection of the wavelength results in one of the pair of atoms having sufficient velocity to exactly cancel that of the parent molecule, and it remains stationary in the lab frame. A trap is formed at the null point between two opposing neodymium permanent magnets. Dissociation of molecules at the field minimum results in the slowest fraction of photofragments remaining trapped. After the ballistic escape of the fastest atoms, the trapped slow atoms are lost only by elastic collisions with the chamber background gas. The measured loss rate is consistent with estimates of the total cross section for only those collisions transferring sufficient kinetic energy to overcome the trapping potential.
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Affiliation(s)
- C J Rennick
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - J Lam
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - W G Doherty
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - T P Softley
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
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37
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Spieler S, Zhong W, Djuricanin P, Nourbakhsh O, Gerhardt I, Enomoto K, Stienkemeier F, Momose T. Microwave lens effect for the J = 0 rotational state of CH3CN. Mol Phys 2013. [DOI: 10.1080/00268976.2013.798044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Steffen Spieler
- a Physikalisches Institut , Universität Freiburg , Freiburg , Germany
| | - Wei Zhong
- b Department of Physics and Astronomy , The University of British Columbia , Vancouver , BC , Canada
| | - Pavle Djuricanin
- c Department of Chemistry , The University of British Columbia , Vancouver , BC , Canada
| | - Omid Nourbakhsh
- b Department of Physics and Astronomy , The University of British Columbia , Vancouver , BC , Canada
| | - Ilja Gerhardt
- c Department of Chemistry , The University of British Columbia , Vancouver , BC , Canada
| | - Katsunari Enomoto
- c Department of Chemistry , The University of British Columbia , Vancouver , BC , Canada
| | | | - Takamasa Momose
- a Physikalisches Institut , Universität Freiburg , Freiburg , Germany
- c Department of Chemistry , The University of British Columbia , Vancouver , BC , Canada
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38
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Pradhan GB, Balakrishnan N, Kendrick BK. Ultracold collisions of O(1D) and H2: The effects of H2vibrational excitation on the production of vibrationally and rotationally excited OH. J Chem Phys 2013; 138:164310. [DOI: 10.1063/1.4802476] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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39
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Evidence for sympathetic vibrational cooling of translationally cold molecules. Nature 2013; 495:490-4. [DOI: 10.1038/nature11937] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 01/23/2013] [Indexed: 01/02/2023]
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40
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Jahn–Teller intersections involving excited states of the F+H2 system: Identification and influence on the reaction system. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.12.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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41
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Zhang M, Wang MS, Xiong DL, Ma N. The influence of femtosecond laser parameters on the wavepacket and population of the diabatic excited states of NaLi. Mol Phys 2013. [DOI: 10.1080/00268976.2012.701768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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42
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Li J, Jiang B, Guo H. Enhancement of bimolecular reactivity by a pre-reaction van der Waals complex: the case of F + H2O → HF + HO. Chem Sci 2013. [DOI: 10.1039/c2sc21457a] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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43
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Henson AB, Gersten S, Shagam Y, Narevicius J, Narevicius E. Observation of Resonances in Penning Ionization Reactions at Sub-Kelvin Temperatures in Merged Beams. Science 2012; 338:234-8. [DOI: 10.1126/science.1229141] [Citation(s) in RCA: 231] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- A. B. Henson
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - S. Gersten
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Y. Shagam
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - J. Narevicius
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - E. Narevicius
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
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Bencsura Á, Lendvay G. Bimolecular Reactions of Vibrationally Excited Molecules. Roaming Atom Mechanism at Low Kinetic Energies. J Phys Chem A 2012; 116:4445-56. [DOI: 10.1021/jp301243a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ákos Bencsura
- Institute of Organic Chemistry,
Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1525, Budapest, P.O. Box 17, Hungary
| | - György Lendvay
- Institute of Materials and Environmental
Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1525, Budapest, P.O. Box 17,
Hungary
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46
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Quenching vibrations by collisions in cold traps: A quantum study for MgH + (X 1Σ + ) with 4He(1S) #. J CHEM SCI 2012. [DOI: 10.1007/s12039-011-0190-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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47
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Jendoubi I, Berriche H, Ben Ouada H, Gadea FX. Structural and Spectroscopic Study of the LiRb Molecule beyond the Born–Oppenheimer Approximation. J Phys Chem A 2012; 116:2945-60. [DOI: 10.1021/jp209106w] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- I. Jendoubi
- Laboratoire
des Interfaces et Matériaux avancés, Département
de Physique, Faculté des Sciences de Monastir Université de Monastir, Avenue de l’Environnement
5019 Monastir, Tunisia
| | - H. Berriche
- Laboratoire
des Interfaces et Matériaux avancés, Département
de Physique, Faculté des Sciences de Monastir Université de Monastir, Avenue de l’Environnement
5019 Monastir, Tunisia
- Physics Department, College of Science, King Khalid University, P.O.B. 9004, Abha, Saudi Arabia
| | - H. Ben Ouada
- Laboratoire
des Interfaces et Matériaux avancés, Département
de Physique, Faculté des Sciences de Monastir Université de Monastir, Avenue de l’Environnement
5019 Monastir, Tunisia
| | - F. X. Gadea
- Laboratoire de Chimie et Physique
Quantique, UMR5626 du CNRS Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 4, France
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48
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Barry JF, Shuman ES, Norrgard EB, DeMille D. Laser radiation pressure slowing of a molecular beam. PHYSICAL REVIEW LETTERS 2012; 108:103002. [PMID: 22463406 DOI: 10.1103/physrevlett.108.103002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate deceleration of a beam of neutral strontium monofluoride molecules using radiative forces. Under certain conditions, the deceleration results in a substantial flux of detected molecules with velocities ≲50 m/s. Simulations and other data indicate that the detection of molecules below this velocity is greatly diminished by transverse divergence from the beam. The observed slowing, from ∼140 m/s, corresponds to scattering ≳10(4) photons. We also observe longitudinal velocity compression under different conditions. Combined with molecular laser cooling techniques, this lays the groundwork to create slow and cold molecular beams suitable for trap loading.
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Affiliation(s)
- J F Barry
- Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520, USA.
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Byrd JN, Côté R, Montgomery JA. Long-range interactions between like homonuclear alkali metal diatoms. J Chem Phys 2011; 135:244307. [DOI: 10.1063/1.3671371] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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50
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Lique F, Li G, Werner HJ, Alexander MH. Communication: Non-adiabatic coupling and resonances in the F + H2 reaction at low energies. J Chem Phys 2011; 134:231101. [DOI: 10.1063/1.3603453] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- François Lique
- LOMC – Université du Havre, 25 Rue Philippe Lebon, BP 540 – 76 058 Le Havre Cedex, France
| | - Guoliang Li
- Institut für Theoretische Chemie, Universität Stuttgart, D-70569 Stuttgart, Germany
| | - Hans-Joachim Werner
- Institut für Theoretische Chemie, Universität Stuttgart, D-70569 Stuttgart, Germany
| | - Millard H. Alexander
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2021, USA
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