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Mirahmadi M, Pérez-Ríos J. Ion-atom-atom three-body recombination: From the cold to the thermal regime. J Chem Phys 2023; 158:024103. [PMID: 36641413 DOI: 10.1063/5.0134132] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We present a study on ion-atom-atom reaction A + A + B+ in a wide range of systems and collision energies ranging from 100 μK to 105 K, analyzing two possible products: molecules and molecular ions. The dynamics is performed via a direct three-body formalism based on a classical trajectory method in hyperspherical coordinates developed in Pérez-Ríos et al. [J. Chem. Phys. 140, 044307 (2014)]. Our chief finding is that the dissociation energy of the molecular ion product acts as a threshold energy, separating the low- and high-energy regimes. In the low-energy regime, the long-range tail of the three-body potential dictates the fate of the reaction and the main reaction product. On the contrary, in the high-energy regime, the short-range of atom-atom and atom-ion interaction potential dominate the dynamics, enhancing molecular formation.
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Affiliation(s)
- Marjan Mirahmadi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Jesús Pérez-Ríos
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA and Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA
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Elkamshishy AA, Greene CH. Triatomic Photoassociation in an Ultracold Atom-Molecule Collision. J Phys Chem A 2023; 127:18-28. [PMID: 36584308 DOI: 10.1021/acs.jpca.2c04727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ultracold collisions of neutral atoms and molecules have been of great interest since experimental advances enabled the cooling and trapping of such species. This study develops a simplified theoretical treatment of a low-energy collision between an alkali atom and a diatomic molecule accompanied by absorption of a photon from an external electromagnetic field. The long-range interaction between the two species is treated, including the atomic spin-orbit interaction. The long-range potential energy curves for the triatomic complex are calculated in realistic detail, while effects of the short-range behavior are mimicked by applying different boundary conditions at the van der Waals length. For neutral colliding species, the leading interaction term is the dipole-dipole interaction. In the case of nonpolar dimers like Cs2, the second leading term is the quadrupole-quadrupole interaction. However, there is also a strong dipole-quadrupole interaction for dimers with a large permanent dipole moment such as NaCs, making the dipole-quadrupole interaction the second leading term for an atom colliding with a polar dimer. Our applications of the simplified treatment show a higher density of trimer states for a polar dimer compared to the case of a nonpolar dimer like Cs2. This is a consequence of the strong quadrupole-dipole coupling between the atom and the dimer dipole moment.
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Affiliation(s)
- Ahmed A Elkamshishy
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana47907, United States
| | - Chris H Greene
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana47907, United States.,Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, Indiana47907, United States
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Camparo J. Nonlinear collision shifts of the 0–0 hyperfine transition due to van der Waals molecule formation. J Chem Phys 2022; 156:044303. [DOI: 10.1063/5.0075939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- James Camparo
- Physical Sciences Laboratories, The Aerospace Corporation, 2380 E. El Segundo Blvd., El Segundo, California 90245, USA
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Mirahmadi M, Pérez-Ríos J. Classical threshold law for the formation of van der Waals molecules. J Chem Phys 2021; 155:094306. [PMID: 34496575 DOI: 10.1063/5.0062812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the role of pairwise long-range interactions in the formation of van der Waals molecules through direct three-body recombination processes A + B + B → AB + B, based on a classical trajectory method in hyperspherical coordinates developed in our earlier works [J. Pérez-Ríos et al., J. Chem. Phys. 140, 044307 (2014); M. Mirahmadi and J. Pérez-Ríos, J. Chem. Phys. 154, 034305 (2021)]. In particular, we find the effective long-range potential in hyperspherical coordinates with an exact expression in terms of dispersion coefficients of pairwise potentials. Exploiting this relation, we derive a classical threshold law for the total cross section and the three-body recombination rate yielding an analytical expression for the three-body recombination rate as a function of the pairwise long-range coefficients of the involved partners.
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Affiliation(s)
- Marjan Mirahmadi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Jesús Pérez-Ríos
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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Mirahmadi M, Pérez-Ríos J. On the formation of van der Waals complexes through three-body recombination. J Chem Phys 2021; 154:034305. [PMID: 33499624 DOI: 10.1063/5.0039610] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we show that van der Waals molecules X-RG (where RG is the rare gas atom) may be created through direct three-body recombination collisions, i.e., X + RG + RG → X-RG + RG. In particular, the three-body recombination rate at temperatures relevant for buffer gas cell experiments is calculated via a classical trajectory method in hyperspherical coordinates [Pérez-Ríos et al., J. Chem. Phys. 140, 044307 (2014)]. As a result, it is found that the formation of van der Waals molecules in buffer gas cells (1 K ≲ T ≲ 10 K) is dominated by the long-range tail (distances larger than the LeRoy radius) of the X-RG interaction. For higher temperatures, the short-range region of the potential becomes more significant. Moreover, we notice that the rate of formation of van der Walls molecules is of the same order of the magnitude independent of the chemical properties of X. As a consequence, almost any X-RG molecule may be created and observed in a buffer gas cell under proper conditions.
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Affiliation(s)
- Marjan Mirahmadi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Jesús Pérez-Ríos
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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Quiros N, Tariq N, Tscherbul TV, Kłos J, Weinstein JD. Cold Anisotropically Interacting van der Waals Molecule: TiHe. PHYSICAL REVIEW LETTERS 2017; 118:213401. [PMID: 28598640 DOI: 10.1103/physrevlett.118.213401] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Indexed: 06/07/2023]
Abstract
We have used laser ablation and helium buffer-gas cooling to produce titanium-helium van der Waals molecules at cryogenic temperatures. The molecules were detected through laser-induced fluorescence spectroscopy. Ground-state Ti(a^{3}F_{2})-He binding energies were determined for the ground and first rotationally excited states from studying equilibrium thermodynamic properties, and found to agree well with theoretical calculations based on newly calculated ab initio Ti-He interaction potentials, opening up novel possibilities for studying the formation, dynamics, and nonuniversal chemistry of van der Waals clusters at low temperatures.
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Affiliation(s)
- Nancy Quiros
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Naima Tariq
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Jacek Kłos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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Kłos J, Hapka M, Chałasiński G, Halvick P, Stoecklin T. Theoretical study of the buffer-gas cooling and trapping of CrH(X6Σ+) by3He atoms. J Chem Phys 2016; 145:214305. [DOI: 10.1063/1.4968529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jacek Kłos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2021, USA
| | - Michał Hapka
- Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland
| | - Grzegorz Chałasiński
- Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland
| | - Philippe Halvick
- Institut des Sciences Moléculaires, Université de Bordeaux, CNRS-UMR 5255, 33405 Talence, France
| | - Thierry Stoecklin
- Institut des Sciences Moléculaires, Université de Bordeaux, CNRS-UMR 5255, 33405 Talence, France
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Cooper GA, Kartouzian A, Gentleman AS, Iskra A, van Wijk R, Mackenzie SR. Dissociation energies of Ag–RG (RG = Ar, Kr, Xe) and AgO molecules from velocity map imaging studies. J Chem Phys 2015; 143:124302. [DOI: 10.1063/1.4931486] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Graham A. Cooper
- Physical and Theoretical Chemistry Laboratory, Oxford Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Aras Kartouzian
- Physical and Theoretical Chemistry Laboratory, Oxford Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom
- Department of Physical Chemistry, Catalysis Research Center, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Alexander S. Gentleman
- Physical and Theoretical Chemistry Laboratory, Oxford Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Andreas Iskra
- Physical and Theoretical Chemistry Laboratory, Oxford Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Robert van Wijk
- Physical and Theoretical Chemistry Laboratory, Oxford Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Stuart R. Mackenzie
- Physical and Theoretical Chemistry Laboratory, Oxford Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom
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Cargnoni F, Ponti A, Mella M. Coinage metal exciplexes with helium atoms: a theoretical study of M*(2L)He(n) (M = Cu, Ag, Au; L = P,D). Phys Chem Chem Phys 2013; 15:18410-23. [PMID: 24072257 DOI: 10.1039/c3cp50250c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure and energetics of exciplexes M*((2)L)He(n) (M = Cu, Ag and Au; L = P and D) in their vibrational ground state are studied by employing diffusion Monte Carlo (DMC). Interaction potentials between the excited coinage metals and He atoms are built using the Diatomics-in-Molecule (DIM) approach and ab initio potential curves for the M((2)L)-He dimers. Extending our previous work [Cargnoni et al., J. Phys. Chem. A, 2011, 115, 7141], we computed the dimer potential for Au in the (2)P and (2)D states, as well for Cu and Ag in the (2)D state, employing basis set superposition error-corrected Configuration Interaction calculations. We found that the (2)Π potential correlating with the (2)P state of Au is substantially less binding than for Ag and Cu, a trend well supported by the M(+) ionic radiuses. Conversely, the interaction potentials between a (n - 1)d(9)ns(2 2)D metal and He present a very weak dependency on M itself or the projection of the angular momentum along the dimer axis. This is due to the screening exerted by the ns(2) electrons on the hole in the (n - 1)d shell. Including the spin-orbit coupling perturbatively in the DIM energy matrix has a major effect on the lowest potential energy surface of the (2)P manifold, the one for Cu allowing the formation of a "belt" of five He atoms while the one for Au being completely repulsive. Conversely, spin-orbit coupling has only a weak effect on the (2)D manifold due to the nearly degenerate nature of the diatomic potentials. Structural and energetic results from DMC have been used to support experimental indications for the formation of metastable exciplexes or the opening of non-radiative depopulation channels in bulk and cold gaseous He.
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Affiliation(s)
- Fausto Cargnoni
- Istituto di Scienze e Tecnologie Molecolari (ISTM), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano, Italy.
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Tariq N, Al Taisan N, Singh V, Weinstein JD. Spectroscopic detection of the LiHe molecule. PHYSICAL REVIEW LETTERS 2013; 110:153201. [PMID: 25167262 DOI: 10.1103/physrevlett.110.153201] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Indexed: 06/03/2023]
Abstract
We use cryogenic helium buffer-gas cooling to form large densities of lithium atoms in a high-density helium gas, from which LiHe molecules form by three-body recombination. These weakly bound van der Waals molecules are detected spectroscopically, and their binding energy is measured from their equilibrium thermodynamic properties.
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Affiliation(s)
- Naima Tariq
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Nada Al Taisan
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Vijay Singh
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
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Loreau J, Sadeghpour HR, Dalgarno A. Potential energy curves for the interaction of Ag(5s) and Ag(5p) with noble gas atoms. J Chem Phys 2013; 138:084301. [DOI: 10.1063/1.4790586] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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