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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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2
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Tacconi M, Bovino S, Gianturco FA. Direct and inverse reactions of LiH+ with He(1S) from quantum calculations: mechanisms and rates. Phys Chem Chem Phys 2011; 14:637-45. [PMID: 22086258 DOI: 10.1039/c1cp22315a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The gas-phase reaction of LiH(+) (X(2)Σ) with He((1)S) atoms, yielding Li(+)He with a small endothermicity for the rotovibrational ground state of the reagents, is analysed using the quantum reactive approach that employs the Negative Imaginary Potential (NIP) scheme discussed earlier in the literature. The dependence of low-T rates on the initial vibrational state of LiH(+) is analysed and the role of low-energy Feshbach resonances is also discussed. The inverse destruction reaction of LiHe(+), a markedly exothermic process, is also investigated and the rates are computed in the same range of temperatures. The possible roles of these reactions in early universe astrophysical networks, in He droplets environments or in cold traps are briefly discussed.
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Affiliation(s)
- M Tacconi
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
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Marinetti F, Gianturco FA. Water as a solute: competitive shell formation in (He,Ne) mixed microdroplets. Phys Chem Chem Phys 2011; 13:2136-44. [PMID: 21116567 DOI: 10.1039/c0cp01342k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quantum Monte Carlo (QMC) stochastic calculations are carried out for a series of mixed rare gas clusters containing He and Ne which further include one H(2)O molecule as a single dopant. The ab initio potentials employed in the calculations, and the structural details provided by the QMC results, clearly reveal that the differences in the interaction forces which exist between the two solvent adatoms and the molecular solute are causing strongly competing environments that generate preferential shell structuring when surrounding the water molecule. The different behaviour of the two solvents, and the energetics of mixing, are analyzed in detail for small aggregates and for larger mixtures, revealing structural effects which originate from the different networking between solvent adatoms.
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Affiliation(s)
- F Marinetti
- Department of Chemistry and CNISM, University of Rome La Sapienza, Piazzale A. Moro 5, 00185 Rome, Italy
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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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Marinetti F, Yurtsever E, Gianturco FA. HCHO in a Cold, Quantum Solvent: Size and Shape of Its “Bubbles” in 4He Droplets from Stochastic Simulations. J Phys Chem A 2010; 114:9725-32. [DOI: 10.1021/jp1018857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F. Marinetti
- Department of Chemistry and CNISM, University of Rome La Sapienza, Piazzale A. Moro 5, 00185 Rome, Italy, and Department of Chemistry, Koç, University, Rumelifeneriyolu, 34450 Sariyer, Istanbul, Turkey
| | - E. Yurtsever
- Department of Chemistry and CNISM, University of Rome La Sapienza, Piazzale A. Moro 5, 00185 Rome, Italy, and Department of Chemistry, Koç, University, Rumelifeneriyolu, 34450 Sariyer, Istanbul, Turkey
| | - F. A. Gianturco
- Department of Chemistry and CNISM, University of Rome La Sapienza, Piazzale A. Moro 5, 00185 Rome, Italy, and Department of Chemistry, Koç, University, Rumelifeneriyolu, 34450 Sariyer, Istanbul, Turkey
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Ferreira da Silva F, Waldburger P, Jaksch S, Mauracher A, Denifl S, Echt O, Märk TD, Scheier P. On the size of ions solvated in helium clusters. Chemistry 2009; 15:7101-8. [PMID: 19533729 DOI: 10.1002/chem.200802554] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Helium nanodroplets are doped with SF(6), C(4)F(8), CCl(4), C(6)H(5)Br, CH(3)I, and I(2). Upon interaction with free electrons a variety of positively and negatively charged cluster ions X(+/-)He(n) are observed where X(+/-) = F(+/-), Cl(+/-), Br(+/-), I(+), I(2) (+), or CH(3)I(+). The yield of these ions versus cluster size n drops at characteristic sizes n(s) that range from n(s) = 10.2+/-0.6 for F(+) to n(s) = 22.2+/-0.2 for Br(-). n(s) values for halide anions are about 70% larger than for the corresponding cations. The steps in the ion yield suggest closure of the first solvation shell. We propose a simple classical model to estimate ionic radii from n(s). Assuming the helium density in the first solvation shell equals the helium bulk density one finds that radii of halide anions in helium are nearly twice as large as in alkali halide crystals, indicating the formation of an anion bubble due to the repulsive forces that derive from the exchange interaction. In spite of the simplicity of our model, anion radii derived from it agree within approximately 10% with values derived from the mobility of halide anions in superfluid bulk helium, and with values computed by quantum Monte Carlo methods for X(-)He(n) cluster anions.
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Affiliation(s)
- Filipe Ferreira da Silva
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität, Technikerstrasse 25, 6020 Innsbruck, Austria
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Coccia E, Marinetti F, Bodo E, Gianturco FA. Chemical solutions in a quantum solvent: anionic electrolytes in 4He nanodroplets. Chemphyschem 2008; 9:1323-30. [PMID: 18461589 DOI: 10.1002/cphc.200800132] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Variational and diffusion Monte Carlo (VMC and DMC) calculations are presented for anionic electrolytes solvated in (4)He. The electrolytes have the general structure X(-)(He)(N), with X=F, Cl, Br and I, and N varying up to 40 (41 for I(-)). The overall interaction potential is obtained from accurate ab initio data for the two-body components and then using the sum-of-potentials approximation. Our computational scheme is a robust procedure, giving us accurate trial wavefunctions that can be used to perform high-quality DMC calculations. The results indicate very marked delocalization and permanence of the liquid-like quantum features of the solvent adatoms surrounding the anionic impurities. This finding stands in contrast to the more structured, solid-like behavior of the quantum solutions with alkali metal cations embedded in He nanodroplets. While other negatively charged species such as H(-) have shown an overall repulsive interaction with He, the present calculations clearly indicate that the halogen anions remain solvated within liquid-like solvent "bubbles" of species-dependent size.
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Affiliation(s)
- Emanuele Coccia
- Department of Chemistry and CNISM, University of Rome La Sapienza, Piazzale A. Moro, 00185 Rome, Italy.
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9
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Baccarelli I, Gianturco FA, Gonzalez-Lezana T, Delgado-Barrio G, Miret-Artés S, Villarreal P. Rovibrational Structures in Floppy Triatomics: Distributed Gaussian Functions Treatment for the Ne2H- System. J Phys Chem A 2006; 110:5487-94. [PMID: 16623480 DOI: 10.1021/jp0563890] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The full sequence of the bound states for a very floppy triatomic complex, Ne2H- in its ground electronic state, are initially computed for the rotationless situation and employing a variational approach that expands the total nuclear wave function over a large set of symmetry-adapted, distributed Gaussian functions and employs accurate atom-atom potential energy data. The results are tested for numerical convergence, compared with the behavior of both its diatomic fragments, Ne2 and NeH-, and further compared with the results for the Ne3 case. The computational analysis is extended to the production of the rotational constants for the very nonclassical ground state vibrational configuration by making use of the previous findings. The method is shown to provide us with several illuminating details on the nanoscopic internal dynamics of this very weakly bound quantum aggregate.
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Affiliation(s)
- Isabella Baccarelli
- Consorzio interuniversitario per le Applicazioni di Supercalcolo Per Universita' e Ricerca (CASPUR), Via dei Tizii 6B, 00185 Roma, Italy
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Bodo E, Yurtsever E, Yurtsever M, Gianturco FA. Ionic dimers in He droplets: Interaction potentials for Li2+–He,Na2+–He, and K2+–He and stability of the smaller clusters. J Chem Phys 2006; 124:74320. [PMID: 16497049 DOI: 10.1063/1.2172610] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We present post Hartree-Fock calculations of the potential energy surfaces (PESs) for the ground electronic states of the three alkali dimer ions Li(2) (+),Na(2) (+), and K(2) (+) interacting with neutral helium. The calculations were carried out for the frozen molecular equilibrium geometries and for an extensive range of the remaining two Jacobi coordinates, R and theta, for which a total of about 1000 points is generated for each surface. The corresponding raw data were then fitted numerically to produce analytic expressions for the three PESs, which were in turn employed to evaluate the bound states of the three trimers for their J=0 configurations: The final spatial features of such bound states are also discussed in detail. The possible behavior of additional systems with more helium atoms surrounding the ionic dopants is gleaned from further calculations on the structural stability of aggregates with up to six He atoms. The validity of a sum-of-potential approximation to yield realistic total energies of the smaller cluster is briefly discussed vis-a-vis the results from many-body calculations.
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Affiliation(s)
- E Bodo
- Department of Chemistry, University of Rome La Sapienza, Rome, Italy
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Bodo E, Gianturco FA, Yurtsever E, Yurtsever M. Neutral and ionic dopants in helium clusters: interaction forces for the and complexes. Mol Phys 2005. [DOI: 10.1080/00268970500190963] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Di Paola C, Sebastianelli F, Bodo E, I. Baccarelli, and, Gianturco FA, Yurtsever M. Microsolvation of Li+ in Small He Clusters. Li+Hen Species from Classical and Quantum Calculations. J Chem Theory Comput 2005; 1:1045-54. [DOI: 10.1021/ct050072m] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- C. Di Paola
- Department of Chemistry, University of Rome “La Sapienza” and INFM, Piazzale A. Moro 5, 00185 Rome, Italy
| | - F. Sebastianelli
- Department of Chemistry, University of Rome “La Sapienza” and INFM, Piazzale A. Moro 5, 00185 Rome, Italy
| | - E. Bodo
- Department of Chemistry, University of Rome “La Sapienza” and INFM, Piazzale A. Moro 5, 00185 Rome, Italy
| | - I. Baccarelli, and
- Department of Chemistry, University of Rome “La Sapienza” and INFM, Piazzale A. Moro 5, 00185 Rome, Italy
| | - F. A. Gianturco
- Department of Chemistry, University of Rome “La Sapienza” and INFM, Piazzale A. Moro 5, 00185 Rome, Italy
| | - M. Yurtsever
- Chemistry Department, Istanbul Technical University, 80626 Maslak, Istanbul, Turkey
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Mella M, Calderoni G, Cargnoni F. Predicting atomic dopant solvation in helium clusters: The MgHen case. J Chem Phys 2005; 123:054328. [PMID: 16108660 DOI: 10.1063/1.1982787] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a quantum Monte Carlo study of the solvation and spectroscopic properties of the Mg-doped helium clusters MgHe(n) with n=2-50. Three high-level [MP4, CCSD(T), and CCSDT] MgHe interaction potentials have been used to study the sensitivity of the dopant location on the shape of the pair interaction. Despite the similar MgHe well depth, the pair distribution functions obtained in the diffusion Monte Carlo simulations markedly differ for the three pair potentials, therefore indicating different solubility properties for Mg in He(n). Moreover, we found interesting size effects for the behavior of the Mg impurity. As a sensitive probe of the solvation properties, the Mg excitation spectra have been simulated for various cluster sizes and compared with the available experimental results. The interaction between the excited 1P Mg atom and the He moiety has been approximated using the diatomics-in-molecules method and the two excited 1pi and 1sigma MgHe potentials. The shape of the simulated MgHe50 spectra shows a substantial dependency on the location of the Mg impurity, and hence on the MgHe pair interaction employed. To unravel the dependency of the solvation behavior on the shape of the computed potentials, exact density-functional theory has been adapted to the case of doped He(n) and various energy distributions have been computed. The results indicate the shape of the repulsive part of the MgHe potential as an important cause of the different behaviors.
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Affiliation(s)
- Massimo Mella
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, United Kingdom.
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Scifoni E, Bodo E, Gianturco FA. Ionic reactions in He nanodroplets: the [LiHHe]+ complex and its possible energy pathways into products from ab initio calculations. J Chem Phys 2005; 122:224312. [PMID: 15974673 DOI: 10.1063/1.1926270] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ab initio calculations at the multiconfiguration self-consistent field level followed by a multireference configuration interaction were carried out along the two possible collinear approaches of the [LiHHe]+ system, while a three-dimensional calculation of the structures of that complex with LiH+ kept at its equilibrium geometry was also completed at the same level of accuracy. The interaction forces of the lowest two electronic states indicate possible reactive behavior, with the first excited potential-energy surface clearly showing a barrierless path to HeH+ product formation. The details of the reactive pathways and their possible bearing on reaction processes, which could occur at the low temperature of a He nanodroplet holding LiH+ as an impurity, are analyzed and discussed.
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Affiliation(s)
- E Scifoni
- Department of Chemistry and Instituto Nazionale di Fisica della Materia, University of Rome La Sapienza, Piazzale A. Moro 5, 00185 Rome, Italy
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Baccarelli I, Gianturco FA, González-Lezana T, Delgado-Barrio G, Miret-Artés S, Villarreal P. A complete configurational study for the bound states of Ne trimers. J Chem Phys 2005; 122:84313. [PMID: 15836045 DOI: 10.1063/1.1850096] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The structural properties and the energetics of the ground and the excited bound states of Ne(3) for zero total angular momentum are examined using different modelings for the two-body interactions. We employ a method consisting of a variational approach with a distributed Gaussian functions (DGF) basis set expansion. We discuss at length the advantages and possible limitations of such an approach, comparing it to other methods which have been applied in the literature to the same system. The DGF method turns out to be very accurate in giving us the bound states energetics and also provides in a natural way a convincing pictorial description of all the states, including those with dominant linear configurations. Additional bound states are found for the Ne(3) system with respect to those indicated in previous works and we suggest a "stabilization" procedure that can be used to assess the truly bound nature of a state. Some considerations on the relative reliability of the examined two-body interactions are also reported.
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Affiliation(s)
- I Baccarelli
- Department of Chemistry and INFM, University of Rome La Sapienza, Rome, Italy
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Sebastianelli F, Baccarelli I, Di Paola C, Gianturco FA. Replacement equivalence of H- and argon in small (Ar)nH- clusters from optimized structure calculations. J Chem Phys 2004; 121:2094-104. [PMID: 15260763 DOI: 10.1063/1.1772367] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The structural properties of some of the smaller ionic clusters of argon atoms containing the atomic impurity H-, ArnH- with n from 2 up to 7, are examined using different modeling for the interactions within each cluster and by employing different theoretical treatments, both classical and quantum, for the energetics. The same calculations are also carried out for the corresponding neutral homogeneous clusters Ar(n+1). The results of the calculations, the physical reliability of the interactions modeling, and the similarities and the difference between the anionic and the neutral complexes are discussed in some detail. The emerging picture shows that, due to specific features of the employed atom-atom potentials, the ArnH- and Ar(n+1) clusters present very similar structures, where the H- dopant substitutes for one of the outer Ar atoms but does not undergo as yet solvation within such small clusters.
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Affiliation(s)
- F Sebastianelli
- Department of Chemistry, University of Rome La Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
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