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Borocci S, Grandinetti F, Sanna N, Zazza C. Noble Gas Anions: An Overview of Strategies and Bonding Motifs. Chem Asian J 2024; 19:e202400191. [PMID: 38735841 DOI: 10.1002/asia.202400191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/30/2024] [Accepted: 05/09/2024] [Indexed: 05/14/2024]
Abstract
This review article aims to provide an overview of the strategies employed to prepare noble gas anions under different environments and experimental conditions, and of the bonding motifs typically occurring in these species. Observed systems include anions fixed into synthesized salts, detected in the gas phase or in high-pressure devices. The major role of the theoretical calculations is also highlighted, not only in support of the experiments, but also as effective in predicting still unreported species. The chemistry of noble gas anions overall appears as a varied and rich paint, offering fascinating opportunities for both experimentalists and theoreticians.
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Affiliation(s)
- Stefano Borocci
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100, Viterbo, Italy
- Istituto per i Sistemi Biologici (ISB) del CNR, Sede di Roma -, Meccanismi di Reazione c/o Dipartimento di Chimica, Sapienza Università di Roma, P.le A. Moro 5, 00185, Rome, Italy
| | - Felice Grandinetti
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100, Viterbo, Italy
- Istituto per i Sistemi Biologici (ISB) del CNR, Sede di Roma -, Meccanismi di Reazione c/o Dipartimento di Chimica, Sapienza Università di Roma, P.le A. Moro 5, 00185, Rome, Italy
| | - Nico Sanna
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100, Viterbo, Italy
- Istituto per la Scienza e Tecnologia dei Plasmi (ISTP) del CNR, Via Amendola 122/D, 70126, Bari, Italy
| | - Costantino Zazza
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100, Viterbo, Italy
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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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3
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González-Lezana T, Echt O, Gatchell M, Bartolomei M, Campos-Martínez J, Scheier P. Solvation of ions in helium. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1794585] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Tomás González-Lezana
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Massimiliano Bartolomei
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - José Campos-Martínez
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
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4
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Mahmoodi-Darian M, Lundberg L, Zöttl S, Scheier P, Echt O. Electron Attachment and Electron Ionization of Formic Acid Clusters Embedded in Helium Nanodroplets. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:787-795. [PMID: 30805883 PMCID: PMC6502787 DOI: 10.1007/s13361-018-02124-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 05/18/2023]
Abstract
We report the results of an experimental study of electron ionization of large helium nanodroplets doped with formic acid (FA). Several homologous series of cluster anions are observed, including [FAn-H]-, undissociated FAn-, and these ions complexed with one or more H2O. Some major features resemble those observed upon sputtering of frozen FA films but they differ significantly from results obtained by electron attachment to bare FA clusters in the gas phase. The FAn- and (H2O)[FAn-H]- series show abrupt onsets above n = 2 and 5, respectively. A prominent resonance in the anion yield occurs at 22.5 eV due to the formation of an intermediate He-*. Also observed are homologous series of [FA-H]- or [FA2-H]- complexed with helium. The cation chemistry is dominated by the production of protonated formic acid clusters, [FAnH]+, but various other homologous cluster ion series are observed as well. Graphical Abstract.
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Affiliation(s)
| | - Linnea Lundberg
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria
| | - Samuel Zöttl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria.
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5
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Thomas DA, Mucha E, Gewinner S, Schöllkopf W, Meijer G, von Helden G. Vibrational Spectroscopy of Fluoroformate, FCO 2-, Trapped in Helium Nanodroplets. J Phys Chem Lett 2018; 9:2305-2310. [PMID: 29669208 DOI: 10.1021/acs.jpclett.8b00664] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Fluoroformate, also known as carbonofluoridate, is an intriguing molecule readily formed by the reductive derivatization of carbon dioxide. In spite of its well-known stability, a detailed structural characterization of the isolated anion has yet to be reported. Presented in this work is the vibrational spectrum of fluoroformate obtained by infrared action spectroscopy of ions trapped in helium nanodroplets, the first application of this technique to a molecular anion. The experimental method yields narrow spectral lines, providing experimental constraints on the structure that can be accurately reproduced using high-level ab initio methods. In addition, two notable Fermi resonances between a fundamental and combination band are observed. The electrostatic potential map of fluoroformate reveals substantial charge density on fluorine as well as on the oxygen atoms, suggesting multiple sites for interaction with hydrogen bond donors and electrophiles, which may in turn lead to intriguing solvation structures and reaction pathways.
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Affiliation(s)
- Daniel A Thomas
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Eike Mucha
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Sandy Gewinner
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Wieland Schöllkopf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
| | - Gert von Helden
- Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6 , 14195 Berlin , Germany
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Harnisch M, Weinberger N, Denifl S, Scheier P, Echt O. Helium Droplets Doped with Sulfur and C 60. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:10919-10924. [PMID: 26045732 PMCID: PMC4450369 DOI: 10.1021/jp510870x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/23/2014] [Indexed: 05/29/2023]
Abstract
Clusters of sulfur are grown by passing superfluid helium nanodroplets through a pickup cell filled with sulfur vapor. In some experiments the droplets are codoped with C60. The doped droplets are collided with energetic electrons and the abundance distributions of positively and negatively charged cluster ions are recorded. We report, specifically, distributions of S m+, S m-, and C60S m- containing up to 41 sulfur atoms. We also observe complexes of sulfur cluster anions with helium; distributions are presented for He n S m- with n ≤ 31 and m ≤ 3. The similarity between anionic and cationic C60S m± spectra is in striking contrast to the large differences between spectra of S m+ and S m-.
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Affiliation(s)
- Martina Harnisch
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Nikolaus Weinberger
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Department
of Physics, University of New Hampshire, Durham, New Hampshire 03824, United States
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7
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Borocci S, Cecchi P, Giordani M, Grandinetti F. Complexes of the noble gases with H3O+: a theoretical investigation on Ng(H3O+) (Ng = He-Xe). EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:171-181. [PMID: 26307697 DOI: 10.1255/ejms.1354] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The geometries, harmonic vibrational frequencies, and binding energies (Bes) of the Ng(H(3)O(+)) complexes (Ng = He-Xe) were investigated at the coupled cluster level of theory, and their bonding situation was assayed by various methods of bonding analysis. The effects of Ng on H(3)O(+) progressively increase from He to Xe, and only He can be regarded as an essentially "innocent" ligand. The binding energies also increase in the same periodic order, and are by far dominated by the "noncovalent" ion-induced dipole interaction arising from the H(3)O(+)-induced polarization of Ng. For Ne, Ar, Kr, and Xe, this term has a larger contribution from the p orbital lying on the bond axis, and two smaller contributions from the p orbitals perpendicular to the bond axis. For the heaviest Ar(H(3)O(+)), Kr(H(3)O(+)), and Xe(H(3)O(+)), BE also has a "covalent" component, which is ascribed to the relatively-appreciable charge transfer from Ng to H(3)O(+).
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Affiliation(s)
- Stefano Borocci
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100 Viterbo, Italy. Istituto per le Metodologie Chimiche del CNR, Via Salaria, Km 29.500, 00015, Monterotondo, RM, Italy.
| | - Patrizio Cecchi
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100 Viterbo, Italy.
| | - Maria Giordani
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100 Viterbo, Italy. Istituto per le Metodologie Chimiche del CNR, Via Salaria, Km 29.500, 00015, Monterotondo, RM, Italy.
| | - Felice Grandinetti
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali (DIBAF), Università della Tuscia, L.go dell'Università, s.n.c., 01100 Viterbo, Italy. Istituto per le Metodologie Chimiche del CNR, Via Salaria, Km 29.500, 00015, Monterotondo, RM, Italy.
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8
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González Flórez AI, Ahn DS, Gewinner S, Schöllkopf W, von Helden G. IR spectroscopy of protonated leu-enkephalin and its 18-crown-6 complex embedded in helium droplets. Phys Chem Chem Phys 2015; 17:21902-11. [DOI: 10.1039/c5cp02172c] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ultracold IR spectra of protonated leu-enkephalin and its 18-crown-6 complex embedded in superfluid helium droplets have been recorded using a free-electron laser as radiation source.
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Affiliation(s)
| | - Doo-Sik Ahn
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | - Sandy Gewinner
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
| | | | - Gert von Helden
- Fritz-Haber-Institut der Max-Planck-Gesellschaft
- 14195 Berlin
- Germany
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9
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Calvo F. Coating Polycyclic Aromatic Hydrocarbon Cations with Helium Clusters: Snowballs and Slush. J Phys Chem A 2014; 119:5959-70. [DOI: 10.1021/jp510799h] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Florent Calvo
- University of Grenoble Alpes, LIPHY, F-38000 Grenoble, France and
- CNRS, LIPHY, F-38000 Grenoble, France
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10
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Issaoui N, Abdessalem K, Ghalla H, Yaghmour SJ, Calvo F, Oujia B. Theoretical investigation of the relative stability of Na+Hen (n = 2–24) clusters: Many-body versus delocalization effects. J Chem Phys 2014; 141:174316. [DOI: 10.1063/1.4900873] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Bartl P, Leidlmair C, Denifl S, Scheier P, Echt O. On the size and structure of helium snowballs formed around charged atoms and clusters of noble gases. J Phys Chem A 2014; 118:8050-9. [PMID: 24128371 PMCID: PMC4166691 DOI: 10.1021/jp406540p] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/04/2013] [Indexed: 11/30/2022]
Abstract
Helium nanodroplets doped with argon, krypton, or xenon are ionized by electrons and analyzed in a mass spectrometer. HenNgx(+) ions containing up to seven noble gas (Ng) atoms and dozens of helium atoms are identified; the high resolution of the mass spectrometer combined with advanced data analysis make it possible to unscramble contributions from isotopologues that have the same nominal mass but different numbers of helium or Ng atoms, such as the magic He20(84)Kr2(+) and the isobaric, nonmagic He41(84)Kr(+). Anomalies in these ion abundances reveal particularly stable ions; several intriguing patterns emerge. Perhaps most astounding are the results for HenAr(+), which show evidence for three distinct, solid-like solvation shells containing 12, 20, and 12 helium atoms. This observation runs counter to the common notion that only the first solvation shell is solid-like but agrees with calculations by Galli et al. for HenNa(+) [J. Phys. Chem. A 2011, 115, 7300] that reveal three shells of icosahedral symmetry. HenArx(+) (2 ≤ x ≤ 7) ions appear to be especially stable if they contain a total of n + x = 19 atoms. A sequence of anomalies in the abundance distribution of HenKrx(+) suggests that rings of six helium atoms are inserted into the solvation shell each time a krypton atom is added to the ionic core, from Kr(+) to Kr3(+). Previously reported strong anomalies at He12Kr2(+) and He12Kr3(+) [Kim , J. H.; et al. J. Chem. Phys. 2006, 124, 214301] are attributed to a contamination. Only minor local anomalies appear in the distributions of HenXex(+) (x ≤ 3). The distributions of HenKr(+) and HenXe(+) show strikingly similar, broad features that are absent from the distribution of HenAr(+); differences are tentatively ascribed to the very different fragmentation dynamics of these ions.
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Affiliation(s)
- Peter Bartl
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Christian Leidlmair
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, United States
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12
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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
![]()
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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13
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Bartl P, Denifl S, Scheier P, Echt O. On the stability of cationic complexes of neon with helium--solving an experimental discrepancy. Phys Chem Chem Phys 2013; 15:16599-604. [PMID: 23958826 DOI: 10.1039/c3cp52550c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Helium nanodroplets are doped with neon and ionized by electrons. The size-dependence of the ion abundance of HenNex(+), identified in high-resolution mass spectra, is deduced for complexes containing up to seven neon atoms and dozens of helium atoms. Particularly stable ions are inferred from anomalies in the abundance distributions. Two pronounced anomalies at n = 11 and 13 in the HenNe(+) series confirm drift-tube data reported by Kojima et al. [T. M. Kojima et al., Z. Phys. D, 1992, 22, 645]. The discrepancy with previously published spectra of neon-doped helium droplets, which did not reveal any abundance anomalies [T. Ruchti et al., J. Chem. Phys., 1998, 109, 10679-10687; C. A. Brindle et al., J. Chem. Phys., 2005, 123, 064312], is most likely due to limited mass resolution, which precluded unambiguous analysis of contributions from different ions with identical nominal mass. However, calculated dissociation energies of HenNe(+) reported so far do not correlate with the present data, possibly because of challenges in correctly treating the linear, asymmetric [He-Ne-He](+) ionic core in HenNe(+). Anomalies identified in the distributions of HenNex(+) for x > 1, including prominent ones at He12Ne2(+) and He14Ne2(+), may help to better understand solvation of Ne(+) and Nex(+) in helium.
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Affiliation(s)
- Peter Bartl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.
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14
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Bartl P, Tanzer K, Mitterdorfer C, Karolczak S, Illenberger E, Denifl S, Scheier P. Electron ionization of different large perfluoroethers embedded in ultracold helium droplets: effective freezing of short-lived decomposition intermediates. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:298-304. [PMID: 23239377 DOI: 10.1002/rcm.6459] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/16/2012] [Accepted: 10/30/2012] [Indexed: 05/22/2023]
Abstract
RATIONALE Electron ionization of three perfluoroethers (PFEs), C(6)F(14)O(3), C(8)F(18)O(4), and C(10)F(20)O(5), is studied in the gas phase and when the molecules are embedded in ultracold helium (He) droplets. The molecules investigated are model compounds for perfluoropolyethers used as lubricants in technical applications. The present study gives insight into possible radiolysis pathways upon radiation exposure. METHODS The experiments utilized a crossed electron/droplet beam apparatus consisting of a He droplet source and pick-up chamber combined with a commercial time-of-flight mass spectrometer. The doped droplets were ionized by electron ionization at 70 eV. RESULTS The He environment strongly affects the ionization patterns in the way that both the molecular ion M(+) and high-mass fragment ions formed by the loss of light neutral species such as F([M-F](+)), or CF(3)OCF(2) ([M-CF(3)OCF(2)](+)), etc., became strong signals in the mass spectrum. These signals were not or only barely visible in the gas-phase experiment and were identified as short lived (< µs) dissociation intermediates which in the gas phase immediately decomposed into lower-mass fragment ions. CONCLUSIONS Ionic fragmentation intermediates are frozen and subsequently stabilized in the He environment. Helium droplets can hence be viewed as a cryogenic laboratory transforming short-lived decomposition intermediates into stable fragment ions appearing as strong signals in the mass spectrum.
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Affiliation(s)
- P Bartl
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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15
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Bartl P, Leidlmair C, Denifl S, Scheier P, Echt O. Cationic complexes of hydrogen with helium. Chemphyschem 2013; 14:227-32. [PMID: 23090688 PMCID: PMC3555426 DOI: 10.1002/cphc.201200664] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Indexed: 11/08/2022]
Abstract
High-resolution mass spectra of helium nanodroplets doped with hydrogen or deuterium reveal that copious amounts of helium can be bound to H(+), H(2)(+), H(3)(+), and larger hydrogen-cluster ions. All conceivable He(n)H(x)(+) stoichiometries are identified if their mass is below the limit of ≈120 u set by the resolution of the spectrometer. Anomalies in the ion yields of He(n)H(x)(+) for x=1, 2, or 3, and n≤30 reveal particularly stable cluster ions. Our results for He(n)H(1)(+) are consistent with conclusions drawn from previous experimental and theoretical studies which were limited to smaller cluster ions. The He(n)H(3)(+) series exhibits a pronounced anomaly at n=12 which was outside the reliable range of earlier experiments. Contrary to findings reported for other diatomic dopant molecules, the monomer ion (i.e. H(2)(+)) retains helium with much greater efficiency than hydrogen-cluster ions.
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Affiliation(s)
- Peter Bartl
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechnikerstraße 25, A-6020 Innsbruck (Austria)
| | - Christian Leidlmair
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechnikerstraße 25, A-6020 Innsbruck (Austria)
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechnikerstraße 25, A-6020 Innsbruck (Austria)
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechnikerstraße 25, A-6020 Innsbruck (Austria)
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechnikerstraße 25, A-6020 Innsbruck (Austria)
- Department of Physics, University of New HampshireDurham, NH 03824 (USA)
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16
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An der Lan L, Bartl P, Leidlmair C, Jochum R, Denifl S, Echt O, Scheier P. Solvation of Na+, K+, and their dimers in helium. Chemistry 2012; 18:4411-8. [PMID: 22374575 PMCID: PMC3350777 DOI: 10.1002/chem.201103432] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Indexed: 11/10/2022]
Abstract
Helium atoms bind strongly to alkali cations which, when embedded in liquid helium, form so-called snowballs. Calculations suggest that helium atoms in the first solvation layer of these snowballs form rigid structures and that their number (n) is well defined, especially for the lighter alkalis. However, experiments have so far failed to accurately determine values of n. We present high-resolution mass spectra of Na+Hen, K+Hen, Na2+Hen and K2+Hen, formed by electron ionization of doped helium droplets; the data allow for a critical comparison with several theoretical studies. For sodium and potassium monomers the spectra indicate that the value of n is slightly smaller than calculated. Na2+Hen displays two distinct anomalies at n=2 and n=6, in agreement with theory; dissociation energies derived from experiment closely track theoretical values. K2+Hen distributions are fairly featureless, which also agrees with predictions.
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Affiliation(s)
- Lukas An der Lan
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
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17
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Ferreira da Silva F, Ptasińska S, Denifl S, Gschliesser D, Postler J, Matias C, Märk TD, Limão-Vieira P, Scheier P. Electron interaction with nitromethane embedded in helium droplets: attachment and ionization measurements. J Chem Phys 2012; 135:174504. [PMID: 22070303 DOI: 10.1063/1.3656680] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Results of a detailed study on electron interactions with nitromethane (CH(3)NO(2)) embedded in helium nanodroplets are reported. Anionic and cationic products formed are analysed by mass spectrometry. When the doped helium droplets are irradiated with low-energy electrons of about 2 eV kinetic energy, exclusively parent cluster anions (CH(3)NO(2))(n)(-) are formed. At 8.5 eV, three anion cluster series are observed, i.e., (CH(3)NO(2))(n)(-), [(CH(3)NO(2))(n)-H](-), and (CH(3)NO(2))(n)NO(2)(-), the latter being the most abundant. The results obtained for anions are compared with previous electron attachment studies with bare nitromethane and nitromethane condensed on a surface. The cation chemistry (induced by electron ionization of the helium matrix at 70 eV and subsequent charge transfer from He(+) to the dopant cluster) is dominated by production of methylated and protonated nitromethane clusters, (CH(3)NO(2))(n)CH(3)(+) and (CH(3)NO(2))(n)H(+).
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Affiliation(s)
- F Ferreira da Silva
- Institut für Ionenphysik und Angewandte Physik and Centre of Molecular Biosciences Innsbruck, Universität Innsbruck, Innsbruck, Austria
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18
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Leidlmair C, Wang Y, Bartl P, Schöbel H, Denifl S, Probst M, Alcamí M, Martín F, Zettergren H, Hansen K, Echt O, Scheier P. Structures, energetics, and dynamics of helium adsorbed on isolated fullerene ions. PHYSICAL REVIEW LETTERS 2012; 108:076101. [PMID: 22401228 DOI: 10.1103/physrevlett.108.076101] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Indexed: 05/27/2023]
Abstract
Helium adsorbed on C(60)(+) and C(70)(+) exhibits phenomena akin to helium on graphite. Mass spectra suggest that commensurate layers form when all carbon hexagons and pentagons are occupied by one He each, but that the solvation shell does not close until 60 He atoms are adsorbed on C(60)(+), or 62 on C(70)(+). Molecular dynamics simulations of C(60)He(n)(+) at 4 K show that the commensurate phase is solid. Helium added to C(60)He(32)(+) will displace some atoms from pentagonal sites, leading to coexistence of a registered layer of immobile atoms interlaced with a nonregistered layer of mobile atoms.
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Affiliation(s)
- Christian Leidlmair
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
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19
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Galli DE, Ceperley DM, Reatto L. Path integral Monte Carlo study of 4He clusters doped with alkali and alkali-earth ions. J Phys Chem A 2011; 115:7300-9. [PMID: 21568337 DOI: 10.1021/jp200617a] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Path integral Monte Carlo calculations of (4)He nanodroplets doped with alkali (Na(+), K(+) and Cs(+)) and alkali-earth (Be(+) and Mg(+)) ions are presented. We study the system at T = 1 K and between 14 and 128 (4)He atoms. For all studied systems, we find that the ion is well localized at the center of the droplet with the formation of a "snowball" of well-defined shells of localized (4)He atoms forming solid-like order in at least the first surrounding shell. The number of surrounding helium shells (two or three) and the number of atoms per shell and the degree of localization of the helium atoms are sensitive to the type of ion. The number of (4)He atoms in the first shell varies from 12 for Na(+) to 18 for Mg(+) and depends weakly on the size of the droplet. The study of the density profile and of the angular correlations shows that the local solid-like order is more pronounced for the alkali ions with Na(+) giving a very stable icosahedral order extending up to three shells.
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Affiliation(s)
- D E Galli
- Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy.
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20
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Grandinetti F. Review: gas-phase ion chemistry of the noble gases: recent advances and future perspectives. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2011; 17:423-463. [PMID: 22173538 DOI: 10.1255/ejms.1151] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This review article surveys recent experimental and theoretical advances in the gas-phase ion chemistry of the noble gases. Covered issues include the interaction of the noble gases with metal and non-metal cations, the conceivable existence of covalent noble-gas anions, the occurrence of ion-molecule reactions involving singly-charged xenon cations, and the occurrence of bond-forming reactions involving doubly-charged cations. Research themes are also highlighted, that are expected to attract further interest in the future.
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Affiliation(s)
- Felice Grandinetti
- Dipartimento per la Innovazione nei sistemi Biologici, Agroalimentari e Forestali, Università della Tuscia, L.go dell'Università, s.n.c., 01100 Viterbo, Italy.
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21
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Schöbel H, Bartl P, Leidlmair C, Daxner M, Zöttl S, Denifl S, Märk TD, Scheier P, Spångberg D, Mauracher A, Bohme DK. Sequential penning ionization: harvesting energy with ions. PHYSICAL REVIEW LETTERS 2010; 105:243402. [PMID: 21231525 DOI: 10.1103/physrevlett.105.243402] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Indexed: 05/30/2023]
Abstract
We report the observation of the ejection of electrons caused by collisions of excited atoms with ions, rather than neutrals, leading to the production of doubly charged ions. Doping superfluid He droplets with methyl iodide and exposing them to electrons enhances the formation of doubly charged iodine atoms at the threshold for the production of two metastable He atoms. These observations point toward a novel ionization process where doubly charged ions are produced by sequential Penning ionization. In some cases, depending on the neutral target, the process also leads to a subsequent Coulomb explosion of the dopant.
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Affiliation(s)
- Harald Schöbel
- Institute for Ion Physics and Applied Physics, University of Innsbruck, 6020 Innsbruck, Austria
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22
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Smolarek S, Brauer NB, Buma WJ, Drabbels M. IR Spectroscopy of Molecular Ions by Nonthermal Ion Ejection from Helium Nanodroplets. J Am Chem Soc 2010; 132:14086-91. [DOI: 10.1021/ja1034655] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Szymon Smolarek
- University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands, and Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nils B. Brauer
- University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands, and Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Wybren J. Buma
- University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands, and Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marcel Drabbels
- University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands, and Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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23
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Wright TG, Breckenridge WH. Radii of atomic ions determined from diatomic ion-He bond lengths. J Phys Chem A 2010; 114:3182-9. [PMID: 20055395 DOI: 10.1021/jp9091927] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We propose a new definition of the effective radius of an atomic ion: the bond distance (R(e)) of the ion/He diatomic complex minus the van der Waals radius of the helium atom. Our rationale is that He is the most chemically inert and least polarizable atom, so that its interaction with the outer portions of the electron cloud causes the smallest perturbation of it. We show that such radii, which we denote R(XHe), make good qualitative sense. We also compare our R(XHe) values to more traditional ionic radii from solid crystal X-ray measurements, as well as estimates of such radii from "ionic" gas-phase MF, MOM, MF(+), and MO molecules, where M is a metal atom. Such comparisons lead to interesting conclusions about bonding in ionic crystals and in simple gas-phase oxide and fluoride molecules. The definition is shown to be reasonable for -1, +1, and even for many of the larger +2 atomic ions. Another advantage of the R(XHe) definition is that it is also consistently valid for ground states and excited states of both neutral atoms and atomic ions, even for open-shell np and nd cases where the electron clouds of the ions are not spherically symmetric and R(XHe) thus depends on the "approach" direction of the He atom. Finally, we note that when there is a contribution from covalent bonding with the He atom, and/or in cases where the ion is small and has a very high charge, so that there is distortion even of the He 1s electrons, R(XHe) is not expected to be representative of the size of the ion. We then suggest that in these cases small, and sometimes unphysical, values of R(XHe) are diagnostic of the fact that simple "physical" interactions have been supplemented by a "chemical" component.
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Affiliation(s)
- Timothy G Wright
- School of Chemistry, University of Nottingham, University Park, United Kingdom NG7 2RD.
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24
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Ferreira da Silva F, Bartl P, Denifl S, Märk TD, Ellis AM, Scheier P. Formation of the Magic L-Serine Octamer in Helium Nanodroplets. Chemphyschem 2010; 11:90-2. [DOI: 10.1002/cphc.200900826] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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25
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Silva FFD, Denifl S, Märk TD, Doltsinis NL, Ellis AM, Scheier P. Electron Attachment to Formamide Clusters in Helium Nanodroplets. J Phys Chem A 2010; 114:1633-8. [DOI: 10.1021/jp909890h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- F. Ferreira da Silva
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria, Department of Physics, King’s College London, The Strand, London WC2R 2LS, United Kingdom, and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - S. Denifl
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria, Department of Physics, King’s College London, The Strand, London WC2R 2LS, United Kingdom, and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - T. D. Märk
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria, Department of Physics, King’s College London, The Strand, London WC2R 2LS, United Kingdom, and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - N. L. Doltsinis
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria, Department of Physics, King’s College London, The Strand, London WC2R 2LS, United Kingdom, and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - A. M. Ellis
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria, Department of Physics, King’s College London, The Strand, London WC2R 2LS, United Kingdom, and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - P. Scheier
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria, Department of Physics, King’s College London, The Strand, London WC2R 2LS, United Kingdom, and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
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26
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Slavícek P, Lewerenz M. Snowballs, quantum solvation and coordination: lead ions inside small helium droplets. Phys Chem Chem Phys 2009; 12:1152-61. [PMID: 20094680 DOI: 10.1039/b918186e] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ab initio calculations are used to construct an analytical many-body potential for Pb(2+)He(n) and Pb(+)He(n) clusters which accounts for non pairwise additive interactions. The potential surface reproduces the global minima for cluster sizes ranging from n = 1 to n = 16 obtained from explicit ab initio calculations and found in a previous search for ultrahigh coordination numbers. Ground state energies and structures obtained by accurate diffusion quantum Monte Carlo calculations are used to investigate if quantum effects qualitatively affect the formation of coordination shells. For Pb(2+) doped clusters a first solvation shell is closed at n = 12 and gradually softened by additional helium atoms which start to form a distinct second shell only at n = 16. Spin-orbit coupling profoundly influences the structure of Pb(+)He(n) clusters and causes a gradual structural evolution without pronounced solvation shells.
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Affiliation(s)
- Petr Slavícek
- Department of Physical Chemistry, Institute of Chemical Technology Prague, Technická 6, 166 28 Prague 6, Czech Republic
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27
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Ferreira da Silva F, Jaksch S, Martins G, Dang HM, Dampc M, Denifl S, Märk TD, Limão-Vieira P, Liu J, Yang S, Ellis AM, Scheier P. Electron attachment and electron ionization of acetic acid clusters embedded in helium nanodroplets. Phys Chem Chem Phys 2009; 11:11631-7. [PMID: 20024436 DOI: 10.1039/b918210a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of incident electrons on acetic acid clusters is explored for the first time. The acetic acid clusters are formed inside liquid helium nanodroplets and both cationic and anionic products ejected into the gas phase are detected by mass spectrometry. The cation chemistry (induced by electron ionization at 100 eV) is dominated by production of protonated acetic acid (Ac) clusters, Ac(n)H(+), although some fragmentation is also observed. In the case of anion production (at 2.8 eV electron energy) there is a clear distinction between the monomer and the clusters. For the monomer the dominant product is the dehydrogenated species, [Ac-H](-), whereas for the clusters both the parent anion, Ac(n)(-), and the dehydrogenated species, [Ac(n)-H](-), have similar abundances. A particularly intriguing contrast between the monomer and cluster anions is that helium atoms are seen attached to the latter whereas no evidence of helium atom attachment is found for the monomer. This surprising observation is attributed to the formation of acyclic (head-to-tail) acetic acid clusters in helium nanodroplets, which have more favourable electronic properties for binding helium atoms. The acyclic clusters represent a local minimum on the potential energy surface and in the case of the dimer this is distinct from the cyclic isomer (the global minimum) identified in gas phase experiments.
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Affiliation(s)
- F Ferreira da Silva
- Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
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