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Zhang J, Buren B, Li Y. A neural network potential energy surface of the Li 3 system and quantum dynamics studies for the 7Li + 6Li 2 → 6Li 7Li + 6Li reaction. Phys Chem Chem Phys 2024; 26:17707-17719. [PMID: 38869465 DOI: 10.1039/d4cp01637h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
A high-precision global potential energy surface (PES) of the Li3 system is constructed based on high-level ab initio calculations, and the root-mean-square error is 5.54 cm-1. The short-range of the PES is fitted by the fundamental invariant neural network (FI-NN) method, while the long-range uses a function with an accurate asymptotic potential energy form, and the two regions are connected by a switching function. Based on the new PES, the statistical quantum-mechanical (SQM) and the time-dependent wave packet (TDWP) methods are used to study the dynamics of 7Li + 6Li2 (v = 0, j = 0) → 6Li7Li + 6Li reactions in the low collision energy region (10-11 to 10-3 cm-1) and the high collision energy region (8 to 800 cm-1), respectively. In the high collision energy region, the calculation results of the SQM method and the TDWP method are inconsistent, indicating that the reaction dynamics does not follow the statistical behavior in the high collision energy region. In addition, we found that the Coriolis coupling effect plays an important role in this reaction. The symmetric forward-backward scattering in the total DCS indicates that the reaction follows the complex-forming reaction mechanism.
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Affiliation(s)
- Jiapeng Zhang
- Department of Physics, Liaoning University, Shenyang 110036, China.
| | - Bayaer Buren
- School of Science, Shenyang University of Technology, Shenyang 110870, China.
| | - Yongqing Li
- Department of Physics, Liaoning University, Shenyang 110036, China.
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2
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Ladjimi H, Bejaoui M, Zrafi W, Berriche H. Potential Energy Surfaces and Arrangement Effects of RbNa 2 Complex. J Phys Chem A 2023; 127:6677-6686. [PMID: 37552554 DOI: 10.1021/acs.jpca.3c01283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Ab initio calculations of alkaline diatomic molecule interactions with alkaline atoms provide detailed information about their electronic structure, vibrational frequencies, and spectroscopic properties, which are difficult to measure experimentally. This knowledge can aid in designing and interpreting experiments and guide the development of computational models and advanced dynamical calculation. Using the quantum chemistry ab initio methods based on multi-reference configuration interaction with Davidson correction (MCSCF/MRCI + Q), atomic effective core potentials, core-polarization potentials, and the interactions between the sodium atom and the NaRb diatomic molecule are investigated. To describe the potential energy surfaces of the RbNa2 system, we introduce two geometries described in the Z-matrix coordinates (Re, R, θ). Potential energy surfaces of the ground state 12A' and the first excited state 22A' were calculated for different approach directions of the sodium atom to the NaRb molecule and two geometries were considered. The first geometry is where the Na atom approaches the Rb atom of the RbNa dimer, and the second one is when it approaches the Na atom of the RbNa dimer. Global minima of the ground and first excited states and conical intersections between these states are determined for both geometries. The RbNa dimer in interaction with the sodium atom is found to be strongly attractive in its first excited state, which may be important for the experimenters particularly in the field of cold alkali polar dimers. Thereafter, the potential energy curves correlated to the lowest-lying dissociation limits are calculated in the linear form for the two geometrical cases (angle θ at 180°) and the atomic arrangement effect is observed.
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Affiliation(s)
- Hela Ladjimi
- Laboratory of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, Monastir 5019, Tunisia
| | - Mohamed Bejaoui
- Laboratory of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, Monastir 5019, Tunisia
| | - Wissem Zrafi
- Laboratory of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, Monastir 5019, Tunisia
| | - Hamid Berriche
- Laboratory of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, Monastir 5019, Tunisia
- Department of Mathematics and Natural Sciences, School of Arts and Sciences, American University of Ras Al Khaimah, Ras Al Khaimah, P.O. Box 10021, United Arab Emirates
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3
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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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4
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Croft JFE, Makrides C, Li M, Petrov A, Kendrick BK, Balakrishnan N, Kotochigova S. Universality and chaoticity in ultracold K+KRb chemical reactions. Nat Commun 2017; 8:15897. [PMID: 28722014 PMCID: PMC5524979 DOI: 10.1038/ncomms15897] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/10/2017] [Indexed: 11/17/2022] Open
Abstract
A fundamental question in the study of chemical reactions is how reactions proceed at a collision energy close to absolute zero. This question is no longer hypothetical: quantum degenerate gases of atoms and molecules can now be created at temperatures lower than a few tens of nanokelvin. Here we consider the benchmark ultracold reaction between, the most-celebrated ultracold molecule, KRb and K. We map out an accurate ab initio ground-state potential energy surface of the K2Rb complex in full dimensionality and report numerically-exact quantum-mechanical reaction dynamics. The distribution of rotationally resolved rates is shown to be Poissonian. An analysis of the hyperspherical adiabatic potential curves explains this statistical character revealing a chaotic distribution for the short-range collision complex that plays a key role in governing the reaction outcome. Studying chemical reactions near zero temperature in detail is challenging both in theory and practice. Here the authors report an explicit quantum mechanical study of the benchmark ultracold reaction between a K atom and a KRb molecule, important for future controlled chemistry experiments.
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Affiliation(s)
- J F E Croft
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
| | - C Makrides
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - M Li
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - A Petrov
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA.,NRC 'Kurchatov Institute' PNPI, Gatchina, Leningrad District 188300 Russia.,Division of Quantum Mechanics, St Petersburg State University, 7/9 Universitetskaya nab., St Petersburg 199034, Russia
| | - B K Kendrick
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - N Balakrishnan
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
| | - S Kotochigova
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
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5
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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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6
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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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7
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Kendrick BK, Hazra J, Balakrishnan N. The geometric phase controls ultracold chemistry. Nat Commun 2015; 6:7918. [PMID: 26224326 PMCID: PMC4532881 DOI: 10.1038/ncomms8918] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 06/22/2015] [Indexed: 11/16/2022] Open
Abstract
The geometric phase is shown to control the outcome of an ultracold chemical reaction. The control is a direct consequence of the sign change on the interference term between two scattering pathways (direct and looping), which contribute to the reactive collision process in the presence of a conical intersection (point of degeneracy between two Born-Oppenheimer electronic potential energy surfaces). The unique properties of the ultracold energy regime lead to an effective quantization of the scattering phase shift enabling maximum constructive or destructive interference between the two pathways. By taking the O+OH→H+O2 reaction as an illustrative example, it is shown that inclusion of the geometric phase modifies ultracold reaction rates by nearly two orders of magnitude. Interesting experimental control possibilities include the application of external electric and magnetic fields that might be used to exploit the geometric phase effect reported here and experimentally switch on or off the reactivity.
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Affiliation(s)
- B. K. Kendrick
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Jisha Hazra
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
| | - N. Balakrishnan
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
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8
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Byrd JN, Jindal N, Molt RW, Bartlett RJ, Sanders BA, Lotrich VF. Molecular cluster perturbation theory. I. Formalism. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1036145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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10
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Cvitaš MT, Althorpe SC. A Chebyshev method for state-to-state reactive scattering using reactant-product decoupling: OH + H2 → H2O + H. J Chem Phys 2013; 139:064307. [DOI: 10.1063/1.4817241] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Buchachenko AA. Numerical method of quantum capture probability determination for molecular collisions at ultralow temperatures. ACTA ACUST UNITED AC 2012. [DOI: 10.3103/s0027131412040037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Affiliation(s)
- Goulven Quéméner
- JILA, University of Colorado,
Boulder, CO 80309-0440, United States
| | - Paul S. Julienne
- Joint Quantum Institute, NIST
and the University of Maryland, Gaithersburg, Maryland 20899-8423,
United States
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13
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García-Vela A, Cabanillas-Vidosa I, Ferrero JC, Pino GA. The role of orbiting resonances in the vibrational relaxation of I(2)(B,v' = 21) by collisions with He at very low energies: a theoretical and experimental study. Phys Chem Chem Phys 2012; 14:5570-80. [PMID: 22434127 DOI: 10.1039/c2cp24061k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The low-energy collisions of I(2)(B,v' = 21) with He involving collision-induced vibrational relaxation of I(2) are investigated both experimentally and by means of wave packet simulations. The theoretical cross sections exhibit a structure of peaks originated by orbiting resonances of the I(2)(B,v' = 21) - He van der Waals complex formed in the I(2) + He collisions. Such a structure has similar characteristics as the structure of peaks found in the experimental cross sections. In fact, four of the five peaks of the measured cross sections appear at positions nearly coincident with those of four of the peaks found in the theoretical cross sections. Thus this result confirms the experimental finding that enhancement of I(2) vibrational relaxation is caused by the population of I(2)(B,v' = 21) - He orbiting resonances populated upon the low-energy collisions. The possibility of using this mechanism in the vibrational cooling of diatomic molecules is discussed.
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Affiliation(s)
- Alberto García-Vela
- Instituto de Física Fundamental, C.S.I.C., Serrano 123, 28006 Madrid, Spain.
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14
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Tang LY, Yan ZC, Shi TY, Babb JF, Mitroy J. The long-range non-additive three-body dispersion interactions for the rare gases, alkali, and alkaline-earth atoms. J Chem Phys 2012; 136:104104. [DOI: 10.1063/1.3691891] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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16
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Tscherbul TV, Sayfutyarova ER, Buchachenko AA, Dalgarno A. He–ThO(1Σ+) interactions at low temperatures: Elastic and inelastic collisions, transport properties, and complex formation in cold4He gas. J Chem Phys 2011; 134:144301. [DOI: 10.1063/1.3575399] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Li X, Brue DA, Kendrick BK, Blandon JD, Parker GA. Geometric phase for collinear conical intersections. I. Geometric phase angle and vector potentials. J Chem Phys 2011; 134:064108. [PMID: 21322662 DOI: 10.1063/1.3549725] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a method for properly treating collinear conical intersections in triatomic systems. The general vector potential (gauge theory) approach for including the geometric phase effects associated with collinear conical intersections in hyperspherical coordinates is presented. The current study develops an introductory method in the treatment of collinear conical intersections by using the phase angle method. The geometric phase angle, η, in terms of purely internal coordinates is derived using the example of a spin-aligned quartet lithium triatomic system. A numerical fit and thus an analytical form for the associated vector potentials are explicitly derived for this triatomic A(3) system. The application of this methodology to AB(2) and ABC systems is also discussed.
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Affiliation(s)
- Xuan Li
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA.
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18
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Cvitaš MT, Althorpe SC. State-to-state reactive scattering in six dimensions using reactant–product decoupling: OH + H2 → H2O + H (J = 0). J Chem Phys 2011; 134:024309. [DOI: 10.1063/1.3525541] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Marko T. Cvitaš
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Stuart C. Althorpe
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
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19
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Juanes-Marcos JC, Quéméner G, Kendrick BK, Balakrishnan N. Ultracold collisions and reactions of vibrationally excited OH radicals with oxygen atoms. Phys Chem Chem Phys 2011; 13:19067-76. [DOI: 10.1039/c1cp21141b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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20
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Soldán P. Potential energy surface for spin-polarized rubidium trimer. J Chem Phys 2010; 132:234308. [DOI: 10.1063/1.3455710] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Chandler DW. Cold and ultracold molecules: Spotlight on orbiting resonances. J Chem Phys 2010; 132:110901. [DOI: 10.1063/1.3357286] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Ren Q, Balint-Kurti GG. Design of infrared laser pulses for the vibrational de-excitation of translationally cold Li2 molecules. J Phys Chem A 2009; 113:14255-60. [PMID: 19569669 DOI: 10.1021/jp902572j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In connection with attempts to form molecular Bose-Einstein condensates, there have been reports in the literature of the preparation of samples of translationally cold alkali metal dimers. The molecules in these samples are generally in excited vibrational levels. To form a stable Bose-Einstein condensate, the molecules must be de-excited to their lowest vibrational state. In this paper, we demonstrate that through the use of optimal control theory, it is possible to design a sequence of infrared laser pulses that will de-excite a sample of (7)Li2 molecules from the v = 10 vibrational level of their (1)Sigma(g)+ ground electronic state to their lowest v = 0 vibrational level with an overall efficiency of 91.1%.
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Affiliation(s)
- Qinghua Ren
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK
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23
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Soldán P, Żuchowski PS, Hutson JM. Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms – a new hope. Faraday Discuss 2009; 142:191-201; discussion 221-55. [DOI: 10.1039/b822769c] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Althorpe SC, Stecher T, Bouakline F. Effect of the geometric phase on nuclear dynamics at a conical intersection: Extension of a recent topological approach from one to two coupled surfaces. J Chem Phys 2008; 129:214117. [DOI: 10.1063/1.3031215] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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25
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Kłos J, Żuchowski PS, Rajchel Ł, Chałasiński G, Szczęśniak MM. Nonadditive interactions in ns2 and spin-polarized ns metal atom trimers. J Chem Phys 2008; 129:134302. [DOI: 10.1063/1.2982801] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Li X, Brue DA, Parker GA. Potential energy surfaces for the 1 (4)A('), 2 (4)A(') 1 (4)A(") and 2 (4)A(") states of Li(3). J Chem Phys 2008; 129:124305. [PMID: 19045021 DOI: 10.1063/1.2985857] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Global potential energy surfaces for the 1 (4)A('), 2 (4)A('), 1 (4)A("), and 2 (4)A(") spin-aligned states of Li(3) are constructed as sums of a diatomics-in-molecules (DIM) term plus a three-body term. The DIM model, using a large basis set of 15 (4)A(") and 22 (4)A(') states, is used to obtain a "mixed-pairwise additive" contribution to the potential. A global fit of the three-body terms conserves the accuracy of the ab initio points of a full configuration-interaction calculation. The resulting fit accurately describes conical intersections for both the 1 (4)A(') and 2 (4)A(') surfaces with a root-mean-square (rms) deviation of 5.4x10(-5) hartree in D(infinityh) geometries and 1.2x10(-4) hartree in C(infinityv) geometries. The global fit appears to be quantitatively correct with a rms deviation of 1.8x10(-4)hartree for 1 (4)A('), 9.2x10(-4) hartree for 2 (4)A('), 2.5x10(-4) hartree for 1 (4)A("), and 5.1x10(-4) hartree for 2 (4)A("). A possible diabolic conical intersection, also called an accidental degeneracy, in C(2v) geometries, indicating a seam of conical intersections in C(s) geometries, is also found in ab initio calculations for A(2) states. As shown in this example, the DIM procedure can be optimized to describe the geometric phase and nonadiabatic effects in multisurface potentials.
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Affiliation(s)
- Xuan Li
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73072, USA.
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27
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Li X, Parker GA, Brumer P, Thanopulos I, Shapiro M. Laser-catalyzed production of ultracold molecules: the 6Li+6Li7Li-->homega6Li-6Li+7Li reaction. PHYSICAL REVIEW LETTERS 2008; 101:043003. [PMID: 18764324 DOI: 10.1103/physrevlett.101.043003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Indexed: 05/26/2023]
Abstract
We show that by using laser catalysis, we can employ translationally cold (Tr approximately 1.75 K) collisions to produce ultracold (0.01 mK<Tp<1 mK) (homonuclear) molecules. We illustrate this approach by studying the laser catalysis of the 6Li+6Li7Li-->homega(6Li6Li7Li)*(1(4)A'')-->homega6Li6Li+7Li reaction in the collinear approximation. Ultracold 6Li6Li product molecules are shown to be produced at an extraordinary yield of up to 99.97%, using moderate laser intensities of I=100 kW/cm(2)-10 MW/cm2.
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Affiliation(s)
- Xuan Li
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, USA.
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28
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Coppage S, Matei P, Stewart B. Absolute level-resolved reactive and inelastic rate constants in Li+Li2*. J Chem Phys 2008; 128:241103. [PMID: 18601310 DOI: 10.1063/1.2951992] [Citation(s) in RCA: 3] [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 have used nuclear parity-changing collisions to obtain absolute level-to-level rate constants for reactive scattering in a triatomic system with identical nuclei. We have determined rate constants for the system (7)Li(2) (*)(A (1)Sigma(u) (+))(v(i)=2,j(i)=19)+(7)Li-->(7)Li+(7)Li(2) (*)(A (1)Sigma(u) (+))(v(f),j(f)), from laser-induced fluorescence spectra of lithium vapor in a heat pipe oven. Parity-preserving collisions yielded measurements of absolute rotationally and vibrationally inelastic rate constants as well. We compare the reactive rate constants with statistical prior distributions and the inelastic results with previously measured results on the Ne+(7)Li(2) (*) system.
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Affiliation(s)
- Steven Coppage
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA
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29
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Li X, Parker GA. Theory of laser enhancement of ultracold reactions: the fermion-boson population transfer by adiabatic passage of 6Li+6Li7Li(Tr=1 mK)-->6Li6Li+7Li(Tp=1 mK). J Chem Phys 2008; 128:184113. [PMID: 18532805 DOI: 10.1063/1.2920186] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a new theory of population transfer by adiabatic passage. This theory relates laser catalysis to adiabatic passage, enhancing chemical reactions with the freedom to choose the translational energies of the reactants and products separately. The process, A+BC<-->(Planck's over omega(p) )ABC*(v)<-->(Planck's over omega(s))AB+C, involves two laser fields that are slowly varying so the process is adiabatic, and sufficiently intense so the population of the intermediate bound complex (ABC) is minimized. We apply this theory to the collinear exchange reaction (6)Li+(7)Li(2)(T(r))<-->(Planck's over omega(p))((6)Li(7)Li(7)Li)*<-->(variant Planck's over 2piomega(s) ) (6)Li(7)Li(T(p))+(7)Li. We show that at translational energies T(p)=T(r)=1 mK with a narrow energy bandwidth of delta(E)=0.01 mK, we can obtain nearly total (> or =98%) population transfer from the reactant to the product states. This can be done with a pump laser and a Stokes laser in an "intuitive" sequence (t(p)<t(s)) at a low intensity (I(p)< or =600 MW/cm(2)) and a "coincident" sequence (t(p)=t(s)) at a higher intensity.
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Affiliation(s)
- Xuan Li
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA.
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Li X, Parker GA, Brumer P, Thanopulos I, Shapiro M. Theory of laser enhancement and suppression of cold reactions: The fermion-boson Li6+Li27↔ℏω0Li6Li7+Li7 radiative collision. J Chem Phys 2008; 128:124314. [DOI: 10.1063/1.2899666] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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