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Al-Oqali AD, Sakhel RR, Sakhel AR. Effect of zero-point motion on properties of quantum particles adsorbed on a substrate. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:245401. [PMID: 38447174 DOI: 10.1088/1361-648x/ad3095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 03/06/2024] [Indexed: 03/08/2024]
Abstract
We qualitatively investigate the effect of zero-point motion (ZPM) on the structure and properties of a film composed of quantum particles adsorbed on a graphite substrate. The amplitude of ZPM is controlled by a change of the particle mass while keeping the interactions fixed. In that sense it is assumed that the interactions can be controlled by future doping methods. The worm-algorithm path integral Monte Carlo (WAPIMC) method is applied to simulate this system in the grand-canonical ensemble, where particles can be exchanged with the external particle reservoir. Another method, namely the multiconfigurational time-dependent Hartree method for bosons is additionally applied to verify some of the WAPIMC results and to provide further information on the entropy and the condensate fraction. Several important findings are reported. It is found that ZPM plays an important role in defining order and disorder in the crystalline structure of the adsorbed film. The total energy of the film drops with a reduction in the amplitude of ZPM, that is, it becomes more negative which is an indication to stronger adsorption. For a few particle numbers, a significant condensate fraction is detected that however drops sharply at critical values of the ZPM amplitude. Most importantly, a connection is established between chaos, in coordinate as well as momentum space, and the Heisenberg uncertainty principle. The importance of the present study lies in the fact that adsorbed two-dimensional films serve as an excellent experimental testbed for demonstrating low-dimensional quantum phenomena in the ground state. The present examination contributes also to a further understanding of the properties of heavy quantum particles adsorbed on substrates.
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Affiliation(s)
- Amer D Al-Oqali
- Department of Physics, Mutah University, Al-Karak 61710, Jordan
| | - Roger R Sakhel
- Department of Physics, Faculty of Science, Isra University, Amman 11622, Jordan
| | - Asaad R Sakhel
- Department of Physics, Faculty of Science, Al-Balqa Applied University, Salt 19117, Jordan
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Rendler N, Scognamiglio A, Barranco M, Pí M, Halberstadt N, Dulitz K, Stienkemeier F. Dynamics of Photoexcited Cs Atoms Attached to Helium Nanodroplets. J Phys Chem A 2021; 125:9048-9059. [PMID: 34619968 DOI: 10.1021/acs.jpca.1c05467] [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
We present an experimental study of the dynamics following the photoexcitation and subsequent photoionization of single Cs atoms on the surface of helium nanodroplets. The dynamics of excited Cs atom desorption and readsorption as well as CsHe exciplex formation are measured by using femtosecond pump-probe velocity map imaging spectroscopy and ion time-of-flight spectrometry. The time scales for the desorption of excited Cs atoms off helium nanodroplets as well as the time scales for CsHe exciplex formation are experimentally determined for the 6p states of Cs. For the 6p 2Π1/2 state, our results confirm that the excited Cs atoms only desorb from the nanodroplet when the excitation wavenumber is blue-shifted from the 6p 2Π1/2 ← 6s 2Σ1/2 resonance. Our results suggest that the dynamics following excitation to the 6p 2Π3/2 state can be described by an evaporation-like desorption mechanism, whereas the dynamics arising from excitation to the 6p 2Σ1/2 state is indicative for a more impulsive desorption process. Furthermore, our results suggest a helium-induced spin-orbit relaxation from the 6p 2Σ1/2 state to the 6p 2Π1/2 state. Our findings largely agree with the results of time-dependent 4He density functional theory (DFT) simulations published earlier [Eur. Phys. J. D 2019, 73, 94].
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Affiliation(s)
- Nicolas Rendler
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Audrey Scognamiglio
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Manuel Barranco
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université de Toulouse, CNRS UMR 5589, 118 route de Narbonne, 31062 Toulouse Cedex 09, France.,Departament FQA, Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Marti Pí
- Departament FQA, Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Nadine Halberstadt
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université de Toulouse, CNRS UMR 5589, 118 route de Narbonne, 31062 Toulouse Cedex 09, France
| | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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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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Theisen M, Lackner F, Ernst WE. Cs atoms on helium nanodroplets and the immersion of Cs+ into the nanodroplet. J Chem Phys 2011; 135:074306. [PMID: 21861569 DOI: 10.1063/1.3624840] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Moritz Theisen
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
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Lebedev V, Moroshkin P, Weis A. Spectroscopy of Nonspherical Atomic Bubbles in Solid Helium. J Phys Chem A 2011; 115:7169-79. [DOI: 10.1021/jp200159s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Lebedev
- Département de Physique, Université de Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland
| | - P. Moroshkin
- Département de Physique, Université de Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland
| | - A. Weis
- Département de Physique, Université de Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland
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Leino M, Viel A, Zillich RE. Electronically excited rubidium atom in helium clusters and films. II. Second excited state and absorption spectrum. J Chem Phys 2011; 134:024316. [DOI: 10.1063/1.3528936] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Markku Leino
- Institut de Physique de Rennes, UMR 6251, CNRS & Université de Rennes 1, F-35042 Rennes, France
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Moroshkin P, Hofer A, Lebedev V, Weis A. Spectroscopy of Cs2, RbCs, and Rb2 in solid 4He. J Chem Phys 2010; 133:174510. [PMID: 21054054 DOI: 10.1063/1.3502469] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present comparative experimental and theoretical studies of the absorption and fluorescence spectra of the alkali-metal dimer molecules Cs(2) and RbCs immersed in a solid helium matrix, thereby extending our recent observations of Rb(2) in solid (4)He. The laser-excited molecular states are mostly quenched by the interaction with the He matrix. The quenching efficiently populates the second lowest excited state of the molecule, i.e., (1) (3)Π((u)) that is metastable in the homonuclear dimers. Molecular excitation and emission bands are modeled by calculating Franck-Condon factors that give a reasonable agreement with the experimental findings.
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Affiliation(s)
- P Moroshkin
- Département de Physique, Université de Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland.
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Leino M, Viel A, Zillich RE. Electronically excited rubidium atom in a helium cluster or film. J Chem Phys 2008; 129:184308. [DOI: 10.1063/1.3009279] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bünermann O, Droppelmann G, Hernando A, Mayol R, Stienkemeier F. Unraveling the Absorption Spectra of Alkali Metal Atoms Attached to Helium Nanodroplets. J Phys Chem A 2007; 111:12684-94. [DOI: 10.1021/jp0760760] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Oliver Bünermann
- Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany, Fakultät für Physik, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany, and Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| | - Georg Droppelmann
- Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany, Fakultät für Physik, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany, and Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| | - Alberto Hernando
- Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany, Fakultät für Physik, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany, and Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| | - Ricardo Mayol
- Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany, Fakultät für Physik, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany, and Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| | - Frank Stienkemeier
- Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany, Fakultät für Physik, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany, and Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
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