1
|
De S, Abid AR, Asmussen JD, Ben Ltaief L, Sishodia K, Ulmer A, Pedersen HB, Krishnan SR, Mudrich M. Fragmentation of water clusters formed in helium nanodroplets by charge transfer and Penning ionization. J Chem Phys 2024; 160:094308. [PMID: 38445733 DOI: 10.1063/5.0194098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Accepted: 02/16/2024] [Indexed: 03/07/2024] Open
Abstract
Helium nanodroplets ("HNDs") are widely used for forming tailor-made clusters and molecular complexes in a cold, transparent, and weakly interacting matrix. The characterization of embedded species by mass spectrometry is often complicated by the fragmentation and trapping of ions in the HNDs. Here, we systematically study fragment ion mass spectra of HND-aggregated water and oxygen clusters following their ionization by charge transfer ionization ("CTI") and Penning ionization ("PEI"). While the efficiency of PEI of embedded clusters is lower than for CTI by about factor 10, both the mean sizes of detected water clusters and the relative yields of unprotonated cluster ions are significantly larger, making PEI a "soft ionization" scheme. However, the tendency of ions to remain bound to HNDs leads to a reduced detection efficiency for large HNDs containing >104 helium atoms. These results are instrumental in determining optimal conditions for mass spectrometry and photoionization spectroscopy of molecular complexes and clusters aggregated in HNDs.
Collapse
Affiliation(s)
- S De
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - A R Abid
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - J D Asmussen
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - L Ben Ltaief
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - K Sishodia
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - A Ulmer
- Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - H B Pedersen
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - S R Krishnan
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - M Mudrich
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| |
Collapse
|
2
|
Reider AM, Mayerhofer J, Martini P, Scheier P, Lushchikova OV. Mixed Cluster Ions of Magnesium and C 60. J Phys Chem A 2024; 128:848-857. [PMID: 38272839 PMCID: PMC10860146 DOI: 10.1021/acs.jpca.3c06902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 01/13/2024] [Accepted: 01/15/2024] [Indexed: 01/27/2024]
Abstract
Magnesium clusters exhibit a pronounced nonmetal-to-metal transition, and the neutral dimer is exceptionally weakly bound. In the present study, we formed pristine Mgnz+ (n = 1-100, z = 1-3) clusters and mixed (C60)mMgnz+ clusters (m = 1-7, z = 1, 2) upon electron irradiation of neutral helium nanodroplets doped with magnesium or a combination of C60 and magnesium. The mass spectra obtained for pristine magnesium cluster ions exhibit anomalies, consistent with previous reports in the literature. The anomalies observed for C60Mgn+ strongly suggest that Mg atoms tend to wet the surface of the single fullerene positioning itself above the center of a pentagonal or hexagonal face, while, for (C60)mMgnz+, the preference for Mg to position itself within the dimples formed by fullerene cages becomes apparent. Besides doubly charged cluster ions, with the smallest member Mg22+, we also observed the formation of triply charged ions Mgn3+ with n > 24. The ion efficiency curves of singly and multiply charged ions exhibit pronounced differences compared to singly charged ions at higher electron energies. These findings indicate that sequential Penning ionization is essential in the formation of doubly and triply charged ions inside doped helium nanodroplets.
Collapse
Affiliation(s)
- Anna Maria Reider
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Jan Mayerhofer
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Paul Martini
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Department
of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Paul Scheier
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Olga V. Lushchikova
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| |
Collapse
|
3
|
Alić J, Messner R, Lackner F, Ernst WE, Šekutor M. London dispersion dominating diamantane packing in helium nanodroplets. Phys Chem Chem Phys 2021; 23:21833-21839. [PMID: 34554159 PMCID: PMC8494270 DOI: 10.1039/d1cp03380h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/16/2021] [Indexed: 11/21/2022]
Abstract
Diamantane clusters formed inside superfluid helium nanodroplets were analyzed by time-of-flight mass spectrometry. Distinct cluster sizes were identified as "magic numbers" and the corresponding feasible structures for clusters consisting of up to 19 diamantane molecules were derived from meta-dynamics simulations and subsequent DFT computations. The obtained interaction energies were attributed to London dispersion attraction. Our findings demonstrate that diamantane units readily form assemblies even at low pressures and near-zero Kelvin temperatures, confirming the importance of the intermolecular dispersion effect for condensation of matter.
Collapse
Affiliation(s)
- Jasna Alić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
| | - Roman Messner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Florian Lackner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Wolfgang E Ernst
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | - Marina Šekutor
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
| |
Collapse
|
4
|
Tiefenthaler L, Kollotzek S, Gatchell M, Hansen K, Scheier P, Echt O. Isotope enrichment in neon clusters grown in helium nanodroplets. J Chem Phys 2020; 153:164305. [PMID: 33138400 DOI: 10.1063/5.0028056] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Neon cluster ions Nes + grown in pre-ionized, mass-to-charge selected helium nanodroplets (HNDs) reveal a strong enrichment of the heavy isotope 22Ne that depends on cluster size s and the experimental conditions. For small sizes, the enrichment is much larger than previously reported for bare neon clusters grown in nozzle expansions and subsequently ionized. The enrichment is traced to the massive evaporation of neon atoms in a collision cell that is used to strip helium from the HNDs. We derive a relation between the enrichment of 22Ne in the cluster ion and its corresponding depletion factor F in the vapor phase. The value thus found for F is in excellent agreement with a theoretical expression that relates isotopic fractionation in two-phase equilibria of atomic gases to the Debye temperature. Furthermore, the difference in zero-point energies between the two isotopes computed from F agrees reasonably well with theoretical studies of neon cluster ions that include nuclear quantum effects in the harmonic approximation. Another fitting parameter provides an estimate for the size si of the precursor of the observed Nes +. The value is in satisfactory agreement with the size estimated by modeling the growth of Nes + and with lower and upper limits deduced from other experimental data. On the other hand, neon clusters grown in neutral HNDs that are subsequently ionized by electron bombardment exhibit no statistically significant isotope enrichment at all. The finding suggests that the extent of ionization-induced dissociation of clusters embedded in HNDs is considerably smaller than that for bare clusters.
Collapse
Affiliation(s)
- Lukas Tiefenthaler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Siegfried Kollotzek
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Klavs Hansen
- Center for Joint Quantum Studies and Department of Physics, Tianjin University, Tianjin 300072, China
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| |
Collapse
|
5
|
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
| |
Collapse
|
6
|
Ghosh A, Cederbaum LS, Gokhberg K. Electron transfer mediated decay in HeLi 2 cluster: Potential energy surfaces and decay widths. J Chem Phys 2019; 150:164309. [PMID: 31042888 DOI: 10.1063/1.5082952] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electron transfer mediated decay (ETMD) is a process responsible for double ionization of dopants in He droplets. It is initiated by producing He+ in the droplet, which is neutralized by ETMD, and has been shown to strongly enhance the dopant's double ionization cross section. The efficiency of ETMD, the spectra of emitted secondary electrons, and the character of the ionic products depend on the nuclear dynamics during the decay. To date, there has been no theoretical investigation of multimode dynamics which accompanies ETMD, which could help to understand such dynamics in a He droplet. In this article, we consider the He-Li2 cluster where an ab initio examination of multimode dynamics during the electronic decay is feasible. Moreover, this cluster can serve as a minimal model for Li2 adsorbed on the droplet's surface-a system where ETMD can be observed experimentally. In He droplets, Li2 can be formed in both the ground X1Σg + and the first excited a3Σu + states. In this article, we present ab initio potential energy surfaces of the electronic states of the He-Li2 cluster involved in ETMD, as well as the respective decay widths. We show that the structure of these surfaces and expected nuclear dynamics strongly depend on the electronic state of Li2. Thus, the overall decay rate and the appearance of the observable electron spectra will be dictated by the electronic structure of the dopant.
Collapse
Affiliation(s)
- Aryya Ghosh
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| | - Lorenz S Cederbaum
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| | - Kirill Gokhberg
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| |
Collapse
|
7
|
Kranabetter L, Martini P, Gitzl N, Kuhn M, Saleem F, Rasul B, Mahmoodi Darian M, Jabbour Al Maalouf E, Sukuba I, Kaiser A, Goulart M, Böhme DK, Scheier P. Uptake and accommodation of water clusters by adamantane clusters in helium droplets: interplay between magic number clusters. Phys Chem Chem Phys 2018; 20:21573-21579. [PMID: 30095137 PMCID: PMC6113683 DOI: 10.1039/c8cp02207k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 07/14/2018] [Indexed: 11/30/2022]
Abstract
We report an experimental study of water clusters as guests in interactions with clusters of adamantane (Ad) as hosts that occur in doped helium droplets at extremely low temperatures. Separate experiments with pure water as dopant showed ready formation of a distribution of water clusters (H2O)mH+ that peaks at m = 11 and extends beyond m = 100 with local maxima at m = 4, 11, 21, 28 and 30 with (H2O)21H+ being the most anomalous and showing the greatest stability with respect to clusters immediately adjacent in water content. When adamantane is also added as a dopant, extensive hydration is seen in the formation of water/adamantane clusters, (H2O)mAdn+; magic number clusters (H2O)21Adn+ are seen for all the adamantane clusters. Other magic numbers for water clusters attached to adamantane, (H2O)mAdn+, are as for pristine protonated water, with m = 28 and m = 30. The icosahedral shell closure of pure adamantane at n = 13 and 19 appears to be preserved with (H2O)21 replacing one adamantane. (H2O)21Ad12+ and (H2O)21Ad18+ stand out in intensity and demonstrate the interplay of magic number water clusters with magic number adamantane clusters, observed perhaps for the first time in gas-phase cluster chemistry. There was no clear evidence for the formation of clathrate hydrates in which adamantane is trapped within structured water.
Collapse
Affiliation(s)
- Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Paul Martini
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Norbert Gitzl
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Martin Kuhn
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Fatima Saleem
- Department of Physics
, University of Sargodha
,
40100 Sargodha
, Pakistan
| | - Bilal Rasul
- Department of Physics
, University of Sargodha
,
40100 Sargodha
, Pakistan
| | | | - Elias Jabbour Al Maalouf
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Ivan Sukuba
- Department of Nuclear Physics and Biophysics
, Comenius University
,
SK-84248 Bratislava
, Slovakia
| | - Alexander Kaiser
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Marcelo Goulart
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| | - Diethard K. Böhme
- Department of Chemistry
, York University
,
Toronto
, ON M3J 1P3
, Canada
.
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik
, Universität Innsbruck
,
Technikerstr. 25
, A-6020 Innsbruck
, Austria
.
| |
Collapse
|
8
|
Goulart M, Zappa F, Ellis AM, Bartl P, Ralser S, Scheier P. Electron ionization of helium droplets containing C60 and alcohol clusters. Phys Chem Chem Phys 2017; 19:24197-24201. [DOI: 10.1039/c7cp02994b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Alcoholic chemical reactions at similar conditions as the interstellar medium can be heavily hampered by the presence of C60.
Collapse
Affiliation(s)
- M. Goulart
- Institut für Ionenphysik und Angewandte Physik
- Innsbruck
- Austria
- Departamento de Física
- UFJF
| | - F. Zappa
- Departamento de Física
- UFJF
- Juiz de Fora
- Brazil
| | - A. M. Ellis
- Department of Chemistry
- University of Leicester
- UK
| | - P. Bartl
- Institut für Ionenphysik und Angewandte Physik
- Innsbruck
- Austria
| | - S. Ralser
- Institut für Ionenphysik und Angewandte Physik
- Innsbruck
- Austria
| | - P. Scheier
- Institut für Ionenphysik und Angewandte Physik
- Innsbruck
- Austria
| |
Collapse
|
9
|
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-.
Collapse
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
| |
Collapse
|
10
|
|
11
|
|
12
|
Daxner M, Denifl S, Scheier P, Echt O. Doubly charged CO 2 clusters formed by ionization of doped helium nanodroplets. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2014; 365-366:200-205. [PMID: 25844051 PMCID: PMC4375666 DOI: 10.1016/j.ijms.2014.01.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/05/2014] [Accepted: 01/22/2014] [Indexed: 06/04/2023]
Abstract
Helium nanodroplets are doped with carbon dioxide and ionized by electrons. Doubly charged cluster ions are, for the first time, identified based on their characteristic patterns of isotopologues. Thanks to the high mass resolution, large dynamic range, and a novel method to eliminate contributions from singly charged ions from the mass spectra, we are able to observe doubly charged cluster ions that are smaller than the ones reported in the past. The likely mechanism by which doubly charged ions are formed in doped helium droplets is discussed.
Collapse
Affiliation(s)
- Matthias Daxner
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, NH 03824, USA
| |
Collapse
|
13
|
Kočišek J, Lengyel J, Fárník M, Slavíček P. Energy and charge transfer in ionized argon coated water clusters. J Chem Phys 2013; 139:214308. [PMID: 24320381 DOI: 10.1063/1.4834715] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J Kočišek
- J. Heyrovský Institute of Physical Chemistry v.v.i., Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague, Czech Republic
| | | | | | | |
Collapse
|
14
|
Mauracher A, Kaiser A, Probst M, Zöttl S, Daxner M, Postler J, Goulart M, Zappa F, Bohme D, Scheier P. Decorating (C 60) n+, n = 1-3, with CO 2 at low temperatures: Sterically enhanced physisorption. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2013; 354-355:271-274. [PMID: 25844047 PMCID: PMC4376293 DOI: 10.1016/j.ijms.2013.06.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 06/21/2013] [Accepted: 06/25/2013] [Indexed: 06/04/2023]
Abstract
Multiple attachment of CO2 to the monomer, dimer and trimer cations of C60 has been observed in the mass spectra of He nanodroplets sequentially doped with C60 and CO2 and exposed to electron ionization at 50 eV. Remarkable anomalies were seen in the ion yield for CO2 coverage for (C60)2+(CO2)8 and (C60)3+(CO2)1,2. These provide insight into the influence of steric properties on the nature of physisorption. The enhanced stabilities of (C60)2+(CO2)8 and (C60)3+(CO2)1,2 are attributed to physisorption inside the "groove" of the dimer and the two "dimples" in the trimer cations of C60. Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects.
Collapse
Affiliation(s)
- A. Mauracher
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - A. Kaiser
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - M. Probst
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - S. Zöttl
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - M. Daxner
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - J. Postler
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - M.M. Goulart
- Departamento de Física, ICE, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, MG 36036-330, Brazil
- CAPES Foundation, Ministry of Education of Brazil, Brasília, DF 70040-020, Brazil
| | - F. Zappa
- Departamento de Física, ICE, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, MG 36036-330, Brazil
| | - D.K. Bohme
- Department of Chemistry, York University, Toronto, Ontario M3 J 1P3, Canada
| | - P. Scheier
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| |
Collapse
|
15
|
Kaiser A, Leidlmair C, Bartl P, Zöttl S, Denifl S, Mauracher A, Probst M, Scheier P, Echt O. Adsorption of hydrogen on neutral and charged fullerene: experiment and theory. J Chem Phys 2013; 138:074311. [PMID: 23445013 DOI: 10.1063/1.4790403] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Helium droplets are doped with fullerenes (either C60 or C70) and hydrogen (H2 or D2) and investigated by high-resolution mass spectrometry. In addition to pure helium and hydrogen cluster ions, hydrogen-fullerene complexes are observed upon electron ionization. The composition of the main ion series is (H2)(n)HC(m)(+) where m = 60 or 70. Another series of even-numbered ions, (H2)(n)C(m)(+), is slightly weaker in stark contrast to pure hydrogen cluster ions for which the even-numbered series (H2)(n)(+) is barely detectable. The ion series (H2)(n)HC(m)(+) and (H2)(n)C(m)(+) exhibit abrupt drops in ion abundance at n = 32 for C60 and 37 for C70, indicating formation of an energetically favorable commensurate phase, with each face of the fullerene ion being covered by one adsorbate molecule. However, the first solvation layer is not complete until a total of 49 H2 are adsorbed on C60(+); the corresponding value for C70(+) is 51. Surprisingly, these values do not exhibit a hydrogen-deuterium isotope effect even though the isotope effect for H2/D2 adsorbates on graphite exceeds 6%. We also observe doubly charged fullerene-deuterium clusters; they, too, exhibit abrupt drops in ion abundance at n = 32 and 37 for C60 and C70, respectively. The findings imply that the charge is localized on the fullerene, stabilizing the system against charge separation. Density functional calculations for C60-hydrogen complexes with up to five hydrogen atoms provide insight into the experimental findings and the structure of the ions. The binding energy of physisorbed H2 is 57 meV for H2C60(+) and (H2)2C60(+), and slightly above 70 meV for H2HC60(+) and (H2)2HC60(+). The lone hydrogen in the odd-numbered complexes is covalently bound atop a carbon atom but a large barrier of 1.69 eV impedes chemisorption of the H2 molecules. Calculations for neutral and doubly charged complexes are presented as well.
Collapse
Affiliation(s)
- A Kaiser
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Echt O, Kaiser A, Zöttl S, Mauracher A, Denifl S, Scheier P. Adsorption of Polar and Nonpolar Molecules on Isolated Cationic C 60 , C 70 , and Their Aggregates. Chempluschem 2013; 78:910-920. [PMID: 31986748 DOI: 10.1002/cplu.201300198] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/26/2013] [Indexed: 11/10/2022]
Abstract
Physisorption on graphite, graphene, nanotubes, and other graphitic structures has been the subject of numerous studies, partly driven by interest in the nature of order in two-dimensional systems, their phase transitions, and the use of graphitic scaffolds for reversible storage of hydrogen at high volumetric density and low mass. In contrast, physisorption on individual fullerenes or small aggregates of fullerenes has remained largely unexplored, last but not least, because of technical challenges. A summary of recent progress in identifying specific adsorption sites on positively charged C60 , C70 , and their aggregates is given in this Minireview. Adsorption energies and storage capacities for helium, hydrogen, methane, oxygen, nitrogen, water, and ammonia are determined. Mass spectrometric data reveal the formation of a commensurate phase in which all hollow sites of C60 or C70 are occupied. This phase is identified for all nonpolar molecules, including oxygen, which does not form a commensurate phase on planar graphite. The polar molecules, on the other hand, do not wet fullerenes and they do not form this commensurate phase. A hierarchy of other distinct adsorption sites are identified for nonpolar molecules, namely, groove sites for fullerene dimers and beyond, and dimple sites for fullerene trimers and beyond. Furthermore, evidence is presented for the preferential adsorption of hydrogen and methane in registered sites on fullerene dimers. The interpretation of experimental data that merely count the number of preferred adsorption sites is aided by molecular dynamics simulations, which utilize interaction potentials derived from ab initio calculations to determine adsorption energies.
Collapse
Affiliation(s)
- Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria).,Department of Physics, University of New Hampshire, Durham, NH 03824 (USA)
| | - Alexander Kaiser
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria)
| | - Samuel Zöttl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria)
| | - Andreas Mauracher
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria)
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria)
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria)
| |
Collapse
|
17
|
Kaiser A, Zöttl S, Bartl P, Leidlmair C, Mauracher A, Probst M, Denifl S, Echt O, Scheier P. Methane adsorption on aggregates of fullerenes: site-selective storage capacities and adsorption energies. CHEMSUSCHEM 2013; 6:1235-44. [PMID: 23744834 PMCID: PMC3799018 DOI: 10.1002/cssc.201300133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Indexed: 05/13/2023]
Abstract
Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118-281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane-methane and fullerene-methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes.
Collapse
Affiliation(s)
- Alexander Kaiser
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Samuel Zöttl
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Peter Bartl
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Christian Leidlmair
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Andreas Mauracher
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Michael Probst
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
- Department of Physics, University of New HampshireDurham, NH 03824 (USA)
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität InnsbruckTechniker Str. 25, 6020 Innsbruck (Austria)
| |
Collapse
|
18
|
Shepperson B, Liu J, Ellis AM, Yang S. Communication: Electron impact ionization of binary H2O∕X clusters in helium nanodroplets: an ab initio perspective. J Chem Phys 2012. [PMID: 23205973 DOI: 10.1063/1.4769810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In a recent experiment (H(2)O)(n)∕X(m) binary clusters (where X = Ar, N(2), CO, CO(2), and several other molecules) were formed in superfluid helium nanodroplets and investigated by electron impact mass spectrometry [Liu et al., Phys. Chem. Chem. Phys. 13, 13920 (2011)]. The addition of dopant X was found to affect the branching ratio between H(3)O(+)(H(2)O)(n) and (H(2)O)(+)(n+2) formation. Specifically, the addition of CO increased the proportion of protonated water cluster ions, whereas dopants such as Ar, N(2), and CO(2), had the opposite effect. In this work ab initio calculations have been performed on [X(H(2)O)(2)](+) ions, where X = Ar, N(2), CO, and CO(2), to try and explain this distinct behavior. CO is found to be unique in that it forms a HOCO-H(3)O(+) unit in the most stable cationic complexes where the binding between HO and CO is stronger than that between H(3)O(+) and OH. Thus, on purely energetic grounds, loss of HOCO rather than CO should be the preferred fragmentation process. No comparable chemistry occurs when X = Ar, N(2), or CO(2) and so the co-dopant requires less energy to depart than OH. The calculations therefore account for the experimental observations and provide evidence that HOCO formation is induced in helium droplets containing (H(2)O)(n) clusters and co-doped with CO when subject to electron impact ionization.
Collapse
Affiliation(s)
- Benjamin Shepperson
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
| | | | | | | |
Collapse
|
19
|
Golan A, Ahmed M. Ionization of Water Clusters Mediated by Exciton Energy Transfer from Argon Clusters. J Phys Chem Lett 2012; 3:458-462. [PMID: 26286046 DOI: 10.1021/jz2016654] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The exciton energy deposited in an argon cluster (Arn, ⟨n = 20⟩) using VUV radiation is transferred to softly ionize doped water clusters ((H2O)n, n = 1-9), leading to the formation of nonfragmented clusters. Following the initial excitation, electronic energy is channeled to ionize the doped water cluster while evaporating the Ar shell, allowing identification of fragmented and complete water cluster ions. Examination of the photoionization efficiency curve shows that cluster evaporation from excitons located above 12.6 eV is not enough to cool the energized water cluster ion and leads to their dissociation to (H2O)n-2H(+) (protonated) clusters.
Collapse
Affiliation(s)
- Amir Golan
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| |
Collapse
|
20
|
Schöbel H, Leidlmair C, Bartl P, Aleem A, Hager M, Echt O, Märk TD, Scheier P. Ion-molecule reactions of ammonia clusters with C60 aggregates embedded in helium droplets. Phys Chem Chem Phys 2010; 13:1092-8. [PMID: 21072422 DOI: 10.1039/c0cp01268h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Helium nanodroplets are co-doped with C(60) and ammonia. Mass spectra obtained by electron ionization reveal cations containing ammonia clusters complexed with up to four C(60) units. The high mass resolution of Δm/m≈ 1/6000 makes it possible to separate the contributions of protonated, unprotonated and dehydrogenated ammonia. C(60) aggregates suppress the proton-transfer reaction which usually favors the appearance of protonated ammonia cluster ions. Unprotonated C(x)(NH(3))(n)(+) ions (x = 60, 120, 180) exceed the abundance of the corresponding protonated ions if n < 5; for larger values of n the abundances of C(60)(NH(3))(n)(+) and C(60)(NH)(n-1)NH(4)(+) become about equal. Dehydrogenated C(60)NH(2)(+) ions are relatively abundant; their formation is attributed to a transient doubly charged C(60)-ammonia complex which forms either by an Auger process or by Penning ionization following charge transfer between the primary He(+) ion and C(60). The abundance of C(x)NH(3)(+) and C(x)NH(4)(+) ions (x = 120 or 180) is one to two orders of magnitude weaker than the abundance of ions containing one or two additional ammonia molecules. However, a model involving evaporation of NH(3) or NH(4) from the presumably weakly bound C(x)NH(3)(+) and C(x)NH(4)(+) ions is at odds with the lack of enhancement in the abundance of C(120)(+) and C(180)(+). Mass spectra of C(60) dimers complexed with water complement a previous study of C(60)(H(2)O)(n)(+) recorded at much lower mass resolution.
Collapse
Affiliation(s)
- Harald Schöbel
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold Franzens Universität, Technikerstr. 25, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | |
Collapse
|