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Albertini S, Gruber E, Zappa F, Krasnokutski S, Laimer F, Scheier P. Chemistry and physics of dopants embedded in helium droplets. MASS SPECTROMETRY REVIEWS 2022; 41:529-567. [PMID: 33993543 DOI: 10.1002/mas.21699] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/20/2021] [Accepted: 04/20/2021] [Indexed: 05/18/2023]
Abstract
Helium droplets represent a cold inert matrix, free of walls with outstanding properties to grow complexes and clusters at conditions that are perfect to simulate cold and dense regions of the interstellar medium. At sub-Kelvin temperatures, barrierless reactions triggered by radicals or ions have been observed and studied by optical spectroscopy and mass spectrometry. The present review summarizes developments of experimental techniques and methods and recent results they enabled.
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Affiliation(s)
- Simon Albertini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Elisabeth Gruber
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Fabio Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Serge Krasnokutski
- Laboratory Astrophysics Group of the MPI for Astronomy, University of Jena, Jena, Germany
| | - Felix Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
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2
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Jara-Cortés J, Leal-Sánchez E, Hernández-Trujillo J. Feynman Force Analysis of Chemical Processes in Terms of Topological Atomic Contributions. J Phys Chem A 2020; 124:6370-6379. [DOI: 10.1021/acs.jpca.0c04171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jesús Jara-Cortés
- Unidad Académica de Ciencias Básicas e Ingenierı́as, Universidad Autónoma de Nayarit, Tepic, 63155, México
| | - Edith Leal-Sánchez
- Departamento de Fı́sica y Quı́mica Teórica, Facultad de Quı́mica, UNAM, México City, 04510, México
| | - Jesús Hernández-Trujillo
- Departamento de Fı́sica y Quı́mica Teórica, Facultad de Quı́mica, UNAM, México City, 04510, México
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3
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Casals-Sainz JL, Jara-Cortés J, Hernández-Trujillo J, Guevara-Vela JM, Francisco E, Pendás ÁM. Exotic Bonding Regimes Uncovered in Excited States. Chemistry 2019; 25:12169-12179. [PMID: 31310392 DOI: 10.1002/chem.201902369] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/15/2019] [Indexed: 11/10/2022]
Abstract
Real-space tools were employed to show that the chemical bonding scenario used routinely to understand ground states lacks the necessary flexibility in excited states. It is shown that, even for two-center, two-electron bonds, the real-space bond orders have exotic values that have never been reported. The nature of these situations was uncovered by using electron-counting techniques that provide an appealing statistical interpretation of bonding descriptors, together with simple physical models. Bond orders greater than one as well as negative bond orders for a single bonding electron pair emerge in situations in which the electrons in the pair show a gregarious (bosonic) instead of the usual lonely (fermionic) behavior. In the first case the gregarious pair is intra-atomic, whereas the coupling is interatomic in the second. A number of examples are used to substantiate these claims.
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Affiliation(s)
- José Luis Casals-Sainz
- Departamento de Química FisicayAnalítica, Facultad de Química, Universidad de Oviedo, 33006, Oviedo, Spain
| | - Jesús Jara-Cortés
- Unidad Académica de Ciencias Básicas e Ingenierias, Universidad Autónoma de Nayarit, Tepic, 63155, México
| | | | - José Manuel Guevara-Vela
- Departamento de Química FisicayAnalítica, Facultad de Química, Universidad de Oviedo, 33006, Oviedo, Spain
| | - Evelio Francisco
- Departamento de Química FisicayAnalítica, Facultad de Química, Universidad de Oviedo, 33006, Oviedo, Spain
| | - Ángel Martín Pendás
- Departamento de Química FisicayAnalítica, Facultad de Química, Universidad de Oviedo, 33006, Oviedo, Spain
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4
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Fine J, Verma D, Jones CF, Wittig C, Vilesov AF. Formation of He4+via electron impact of helium droplets. J Chem Phys 2018; 148:044302. [DOI: 10.1063/1.5001715] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jordan Fine
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Deepak Verma
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Curtis F. Jones
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Curt Wittig
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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5
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Jara-Cortés J, Guevara-Vela JM, Martín Pendás Á, Hernández-Trujillo J. Chemical bonding in excited states: Energy transfer and charge redistribution from a real space perspective. J Comput Chem 2017; 38:957-970. [PMID: 28266036 DOI: 10.1002/jcc.24769] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 01/25/2017] [Accepted: 01/27/2017] [Indexed: 11/11/2022]
Abstract
This work provides a novel interpretation of elementary processes of photophysical relevance from the standpoint of the electron density using simple model reactions. These include excited states of H2 taken as a prototype for a covalent bond, excimer formation of He2 to analyze non-covalent interactions, charge transfer by an avoided crossing of electronic states in LiF and conical interesections involved in the intramolecular scrambling in C2 H4 . The changes of the atomic and interaction energy components along the potential energy profiles are described by the interacting quantum atoms approach and the quantum theory of atoms in molecules. Additionally, the topological analysis of one- and two-electron density functions is used to explore basic reaction mechanisms involving excited and degenerate states in connection with the virial theorem. This real space approach allows to describe these processes in a unified way, showing its versatility and utility in the study of chemical systems in excited states. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Jesús Jara-Cortés
- Departamento de Física y Química Teórica, Facultad de Química, UNAM, México City, 04510, México
| | - José Manuel Guevara-Vela
- Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, 33006, Oviedo, Spain
| | - Ángel Martín Pendás
- Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, 33006, Oviedo, Spain
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6
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Rodríguez-Cantano R, González-Lezana T, Villarreal P. Path integral Monte Carlo investigations on doped helium clusters. INT REV PHYS CHEM 2016. [DOI: 10.1080/0144235x.2015.1132595] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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Villarreal P, Rodríguez-Cantano R, González-Lezana T, Prosmiti R, Delgado-Barrio G, Gianturco FA. Quantum Features of Anionic Species He*⁻ and He₂*⁻ in Small He(N) Clusters. J Phys Chem A 2015; 119:11574-82. [PMID: 26517581 DOI: 10.1021/acs.jpca.5b08470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present variational calculations on systems containing a few boson helium atoms attached to electronically excited atomic and molecular helium anions He*⁻ and He₂*⁻ and characterize their structures and energetics. Previously reported high-level ab initio results [Huber, S. E.; Mauracher, A. Mol. Phys. 2014, 112, 794] to describe the interactions between excited (metastable) anions and a neutral He atom have been employed. For the case of the atomic species He*⁻, the corresponding interaction with He suggests large anharmonicity effects due to the presence of a deep well of ∼17,500 cm⁻¹ at short distances, together with a more external shallow secondary well of ∼4 cm⁻¹, both supporting bound levels. Moreover, when a sum of pairwise interactions is assumed to describe the full PES corresponding to the presence of several neutral He atoms, geometrical constraints already predict the complete solvation of the anionic impurity by six helium atoms, giving rise to a bipyramidal structure. In turn, for the anisotropic weak interaction He-He₂*⁻, where the anionic dimer is considered as a rigid rotor, the obtained structures show the tendency of the helium atoms to pack themselves together and largely far away from the dopant, thereby confirming the heliophobic character of He₂*⁻.
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Affiliation(s)
- Pablo Villarreal
- Instituto de Fı́sica Fundamental, IFF-CSIC , Serrano 123, 28006 Madrid, Spain
| | | | | | - Rita Prosmiti
- Instituto de Fı́sica Fundamental, IFF-CSIC , Serrano 123, 28006 Madrid, Spain
| | | | - Franco A Gianturco
- Institute of Ion Physics, The University of Innsbruck , Technikerstrasse 25, 6020 Innsbruck, Austria.,Scuola Normale Superiore ,Piazza dei Cavalieri 7, 56126 Pisa, Italy
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8
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Renzler M, Daxner M, Weinberger N, Denifl S, Scheier P, Echt O. On subthreshold ionization of helium droplets, ejection of He(+), and the role of anions. Phys Chem Chem Phys 2015; 16:22466-70. [PMID: 25230760 DOI: 10.1039/c4cp03236e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanism of ionization of helium droplets has been investigated in numerous reports but one observation has not found a satisfactory explanation: How are He(+) ions formed and ejected from undoped droplets at electron energies below the ionization threshold of the free atom? Does this path exist at all? A measurement of the ion yields of He(+) and He2(+) as a function of electron energy, electron emission current, and droplet size reveals that metastable He*(-) anions play a crucial role in the formation of free He(+) at subthreshold energies. The proposed model is testable.
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Affiliation(s)
- Michael Renzler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.
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9
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Rodríguez-Cantano R, González-Lezana T, Villarreal P, Gianturco FA. A configurational study of helium clusters doped with He∗− and He2∗−. J Chem Phys 2015; 142:104303. [DOI: 10.1063/1.4913958] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
| | | | - Pablo Villarreal
- Instituto de Física Fundamental, CSIC, Serrano 123, 28006 Madrid, Spain
| | - Franco A. Gianturco
- Institute of Ion Physics, The University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austriaand Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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10
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Mauracher A, Daxner M, Postler J, Huber S, Denifl S, Scheier P, Toennies JP. Detection of Negative Charge Carriers in Superfluid Helium Droplets: The Metastable Anions He *- and He 2*-. J Phys Chem Lett 2014; 5:2444-2449. [PMID: 25068008 PMCID: PMC4106244 DOI: 10.1021/jz500917z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/20/2014] [Indexed: 05/13/2023]
Abstract
Helium droplets provide the possibility to study phenomena at the very low temperatures at which quantum mechanical effects are more pronounced and fewer quantum states have significant occupation probabilities. Understanding the migration of either positive or negative charges in liquid helium is essential to comprehend charge-induced processes in molecular systems embedded in helium droplets. Here, we report the resonant formation of excited metastable atomic and molecular helium anions in superfluid helium droplets upon electron impact. Although the molecular anion is heliophobic and migrates toward the surface of the helium droplet, the excited metastable atomic helium anion is bound within the helium droplet and exhibits high mobility. The atomic anion is shown to be responsible for the formation of molecular dopant anions upon charge transfer and thus, we clarify the nature of the previously unidentified fast exotic negative charge carrier found in bulk liquid helium.
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Affiliation(s)
- Andreas Mauracher
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Matthias Daxner
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Johannes Postler
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Stefan
E. Huber
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
- P. Scheier. E-mail: . Phone: +43 512 507 52260. Fax: +43 512 507
2922
| | - J. Peter Toennies
- Max
Planck Institut für Dynamik und Selbstorganisation, Am Fassberg 17, D-37077 Göttingen, Germany
- J. P. Toennies.
E-mail: . Phone: +49 551 5176
600.
Fax: +49 551 5176 575
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11
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Postler J, Vizcaino V, Denifl S, Zappa F, Ralser S, Daxner M, Illenberger E, Scheier P. Electron attachment to CO2 embedded in superfluid He droplets. J Phys Chem A 2014; 118:6553-9. [PMID: 24818738 PMCID: PMC4141896 DOI: 10.1021/jp503179d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
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Electron attachment to CO2 embedded in superfluid He
droplets leads to ionic complexes of the form (CO2)n– and (CO2)nO– and, at much lower intensities,
He containing ions of the form Hem(CO2)nO–. At low
energies (<5 eV), predominantly the non-decomposed complexes (CO2)n– are formed
via two resonance contributions, similar to electron attachment to
pristine CO2 clusters. The significantly different shapes
and relative resonance positions, however, indicate particular quenching
and mediation processes in CO2@He. A series of further
resonances in the energy range up to 67 eV can be assigned to electronic
excitation of He and capture of the inelastically scattered electron
generating (CO2)n– and two additional processes where an intermediately formed He*
leads to the nonstoichiometric anions (CO2)nO–.
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Affiliation(s)
- Johannes Postler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck , Technikerstrasse 25, A-6020 Innsbruck, Austria
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