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Chartkunchand KC, Stockett MH, Anderson EK, Eklund G, Kristiansson MK, Kamińska M, de Ruette N, Blom M, Björkhage M, Källberg A, Löfgren P, Reinhed P, Rosén S, Simonsson A, Zettergren H, Schmidt HT, Cederquist H. Dianion diagnostics in DESIREE: High-sensitivity detection of C n2- from a sputter ion source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:033112. [PMID: 29604753 DOI: 10.1063/1.5010077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A sputter ion source with a solid graphite target has been used to produce dianions with a focus on carbon cluster dianions, Cn2-, with n = 7-24. Singly and doubly charged anions from the source were accelerated together to kinetic energies of 10 keV per atomic unit of charge and injected into one of the cryogenic (13 K) ion-beam storage rings of the Double ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous decay of internally hot Cn2- dianions injected into the ring yielded Cn- anions with kinetic energies of 20 keV, which were counted with a microchannel plate detector. Mass spectra produced by scanning the magnetic field of a 90° analyzing magnet on the ion injection line reflect the production of internally hot C72- - C242- dianions with lifetimes in the range of tens of microseconds to milliseconds. In spite of the high sensitivity of this method, no conclusive evidence of C62- was found while there was a clear C72- signal with the expected isotopic distribution. This is consistent with earlier experimental studies and with theoretical predictions. An upper limit is deduced for a C62- signal that is two orders-of-magnitude smaller than that for C72-. In addition, CnO2- and CnCu2- dianions were detected.
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Affiliation(s)
- K C Chartkunchand
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - E K Anderson
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - G Eklund
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M K Kristiansson
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M Kamińska
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - N de Ruette
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M Blom
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - M Björkhage
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - A Källberg
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - P Löfgren
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - P Reinhed
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - S Rosén
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - A Simonsson
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - H T Schmidt
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
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Affiliation(s)
- Xue-Bin Wang
- Department of Physics, Washington State University, Richland, Washington 99354, and Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352;
| | - Lai-Sheng Wang
- Department of Physics, Washington State University, Richland, Washington 99354, and Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352;
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Franzreb K, Sommerfeld T, Williams P. Small gas-phase dianions of Zn3O42−, Zn4O52−, CuZn2O42−, Si2GeO62−, Ti2O52−and Ti3O72−. Phys Chem Chem Phys 2007; 9:846-52. [PMID: 17287878 DOI: 10.1039/b615088h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We have searched for new species of small oxygen-containing gas-phase dianions produced in a secondary ion mass spectrometer by Cs+ ion bombardment of solid samples with simultaneous exposure of their surfaces to O2 gas. The targets were a pure zinc metal foil, a copper-contaminated zinc-based coin, two silicon-germanium samples (Si(1-x)Ge(x)(with x= 6.5% or 27%)) and a piece of titanium metal. The novel dianions Zn3O(4)(2-), Zn4O(5)(2-), CuZn2O(4)(2-), Si2GeO(6)(2-), Ti2O(5)(2-) and Ti3O(7)(2-) have been observed at half-integer m/z values in the negative ion mass spectra. The heptamer dianions Zn3O(4)(2-) and Ti2O(5)(2-) have been unambiguously identified by their isotopic abundances. Their flight times through the mass spectrometer are approximately 20 micros and approximately 17 micros, respectively. The geometrical structures of the two heptamer dianions Ti2O(5)(2-), and Zn3O(4)(2-) are investigated using ab initio methods, and the identified isomers are compared to those of the novel Ge2O(5)(2-) and the known Si2O(5)(2-) and Be3O(4)(2-) dianions.
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Affiliation(s)
- Klaus Franzreb
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA
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Chen MD, Li XB, Yang J, Zhang QE, Au CT. A Density Functional Study on Beryllium-Doped Carbon Dianion Clusters CnBe2- (n = 4−14). J Phys Chem A 2006; 110:4502-8. [PMID: 16571056 DOI: 10.1021/jp054830g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Making use of the software of molecular graphics, we designed numerous models of C(n)()Be(2-) (n = 4-14). We carried out geometry optimization and calculation on vibration frequency by means of the B3LYP density functional method. After comparison of structure stability, we found that the ground-state isomers of C(n)()Be(2-) (n = 4-14) are linear with the beryllium atom located inside the C(n)() chain. When a side carbon chain is with an even number of carbon atoms, it is polyacetylene-like, whereas when a side chain is with an odd number of carbon atoms, it is cumulene-like. The C(n)Be(2-) (n = 4-14) clusters with an even number of carbon atoms are more stable than that with an odd number of carbon atoms, matching the peak pattern observed in accelerator mass spectrometry (AMS) and Coulomb Explosion Imaging (CEI) investigations of C(n)()Be(2-) (n = 4-14). The trend of such odd/even alternation is explained based on concepts of bonding characteristics, electronic configuration, electron detachment, and incremental binding energy.
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Affiliation(s)
- M D Chen
- State Key Laboratory of Physical Chemistry of Solid Surface, Department of Chemistry, Center for Theoretical Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
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Dreuw A. Electronic and structural properties of Ben-1On2- (n=3–6) , MgBe2O42- and CuBe2O42-. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.11.107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Feuerbacher S, Cederbaum LS. A small and stable covalently bound trianion. J Chem Phys 2006; 124:044320. [PMID: 16460175 DOI: 10.1063/1.2162894] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Stable doubly charged anions have become well known over the past decade, but the knowledge about higher-charged molecules is still sparse. Especially the minimum size of a covalently bound trianion which is still stable is an open question. Here, we present the smallest trianion of this kind known up to now, namely, B(C(2)CO(2))(3) (3-). After establishing its geometrical parameters, we investigate its stability with respect to electron autodetachment and fragmentation of the molecular framework. Our results lend strong support to the notion that this trianion indeed represents a stable compound which should be observable in the gas phase.
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Affiliation(s)
- Sven Feuerbacher
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany.
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Franzreb K, Williams P. Small gas-phase dianions produced by sputtering and gas flooding. J Chem Phys 2005; 123:224312. [PMID: 16375481 DOI: 10.1063/1.2136154] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We have extended our previous experiment [Schauer et al., Phys. Rev. Lett. 65, 625 (1990)] where we had produced small gas-phase dianion clusters of C(n) (2-)(n > or =7) by means of sputtering a graphite surface by Cs(+) ion bombardment. Our detection sensitivity for small C(n) (2-) could now be increased by a factor of about 50 for odd n. Nevertheless, a search for the elusive pentamer dianion of C(5) (2-) was not successful. As an upper limit, the sputtered flux of C(5) (2-) must be at least a factor of 5000 lower than that of C(7) (2-), provided that the lifetime of C(5) (2-) is sufficiently long to allow its detection by mass spectrometry. When oxygen gas (flooding with either O(2) or with N(2)O) was supplied to the Cs(+)-bombarded graphite surface, small dianions of OC(n) (2-)(5< or =n < or =14) and O(2)C(7) (2-) were observed in addition to C(n) (2-)(n > or =7). Similarly, Cs(+) sputtering of graphite with simultaneous SF(6) gas flooding produced SC(n) (2-)(6< or =n< or =18). Mixed nitrogen-carbon or fluorine-carbon dianion clusters could not be observed by these means. Attempts to detect mixed metal-fluoride dianions for SF(6) gas flooding of various Cs(+)-bombarded metal surfaces were successful for the case of Zr, where metastable ZrF(6) (2-) was observed. Cs(+) bombardment of a silicon carbide (SiC) wafer produced SiC(n) (2-) (n=6,8,10). When oxygen gas was supplied to the Cs(+)-bombarded SiC surface, small dianions of SiOC(n) (2-) (n=4,6,8) and of SiO(2)C(n) (2-) (n=4,6) as well as a heavier unidentified dianion (at mz=98.5) were observed. For toluene (C(7)H(8)) vapor flooding of a Cs(+)-bombarded graphite surface, several hydrocarbon dianion clusters of C(n)H(m) (2-)(n> or =7) were produced in addition to C(n) (2-)(n> or =7), while smaller C(n)H(m) (2-) with n< or =6 could not be observed. BeC(n) (2-) (n=4,6,8,10), Be(2)C(6) (2-), as well as BeC(8)H(m) (2-) (with m=2 and/or m=1) were observed for toluene vapor flooding of a Cs(+)-bombarded beryllium metal foil. The metastable pentamer (9)Be(12)C(4) (2-) at mz=28.5 was the smallest and lightest dianion molecule that we could detect. The small dianion clusters of SC(n) (2-), OC(n) (2-), BeC(n) (2-), and SiO(m)C(n) (2-) (m=0,1,2) have different abundance patterns. A resemblance exists between the abundance patterns of BeC(n) (2-) and SiC(n) (2-), even though calculated molecular structures of BeC(6) (2-) and SiC(6) (2-) are different. The abundance pattern of SC(n) (2-) is fairly similar to that of C(n) (2-).
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Affiliation(s)
- Klaus Franzreb
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA
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Löffler D, Weber JM, Kappes MM. Photodetachment spectroscopy of PtBr42−: Probing the Coulomb barrier of a doubly charged anion. J Chem Phys 2005; 123:224308. [PMID: 16375477 DOI: 10.1063/1.2135769] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We probe the repulsive Coulomb barrier of the doubly charged anion PtBr(4) (2-) by photodetachment spectroscopy. The results are discussed in terms of models for the photoemission process, the excitation spectrum of PtBr(4) (2-), and calculations of the energy-dependent tunneling probability for various model potentials.
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Affiliation(s)
- D Löffler
- Institut für Physikalische Chemie, Universität Karlsruhe, D-76128 Karlsruhe, Germany
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Feuerbacher S, Cederbaum LS. Stable and Long-Lived Trianions in the Gas Phase. J Phys Chem A 2005; 109:11401-6. [PMID: 16354027 DOI: 10.1021/jp053305e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stable doubly charged anions have become well known over the past decade, but the knowledge about higher charged molecules is still sparse. In this article, we discuss the current status of trianions. The different species, both from experimental and theoretical work, are classified according to their bonding characteristics, that is, ionic, metallic, or covalent. Both stability with respect to electron autodetachment and with respect to dissociation is covered. New results on the currently smallest stable covalently bound trianion are also shown. Last, we outline future perspectives in the field of multiply charged anions.
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Affiliation(s)
- Sven Feuerbacher
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
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Liu B, Hvelplund P, Brøndsted Nielsen S. Multiply-charged negative clusters of adenosine-5'-monophosphate in the gas phase. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2005; 16:1840-5. [PMID: 16185890 DOI: 10.1016/j.jasms.2005.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 07/15/2005] [Accepted: 07/15/2005] [Indexed: 05/04/2023]
Abstract
Multiply-charged noncovalent cluster anions of adenosine-5'-monophosphate (AMP) were formed by electrospray ionization (ESI). Ions in higher charge states were observed when the ions were accumulated in an ion trap with helium buffer gas before detection. We determined the smallest size (n(a)) or appearance size as a function of charge state (q), i.e., n(a) = 4 for q = 2, n(a) = 8 for q = 3, and n(a) = 13 for q = 4. The relation between n(a) and q can be described by a charged droplet model. When the size is larger than n(a) for a given q, the fragmentation pathway of an anion cluster is dominated by loss of neutral fragments. In contrast, when the size approaches the appearance size, only charged fragments are formed.
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Affiliation(s)
- Bo Liu
- Department of Physics and Astronomy, University of Aarhus, Aarhus, Denmark.
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Ehrler OT, Furche F, Weber JM, Kappes MM. Photoelectron spectroscopy of fullerene dianions C762−, C782−, and C842−. J Chem Phys 2005; 122:094321. [PMID: 15836142 DOI: 10.1063/1.1859272] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report laser photoelectron spectra of the doubly negatively charged fullerenes C(76) (2-), C(78) (2-), and C(84) (2-) at 2.33, 3.49, and 4.66 eV photon energy. From these spectra, second electron affinities and vertical detachment energies, as well as estimates for the repulsive Coulomb barriers are obtained. These results are discussed in the context of electrostatic models. They reveal that fullerenes are similar to conducting spheres, with electronic properties scaling with their size. The experimental spectra are compared with the accessible excited states of the respective singly charged product ions calculated in the framework of time dependent density functional theory.
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Affiliation(s)
- Oli T Ehrler
- Institut für Physikalische Chemie, Universität Karlsruhe, Kaiserstrasse 12, D-76128 Karlsruhe, Germany
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Feuerbacher S, Cederbaum LS. Influence of delocalization on the stability of dianions: study of a systematic series of dianions with growing electronic localization. J Am Chem Soc 2003; 125:9531-7. [PMID: 12889984 DOI: 10.1021/ja035878f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic stability of a dianion is influenced by the degree of delocalization of its electrons, but it is generally not possible to separate this influence from other effects. Here, we investigate by theoretical means the sequence of dianions consisting of phen-1,4-ylenbis(ethynide) and seven of its derivatives obtained by hydrogenating the benzene core in several steps. These dianions are structurally similar and mainly differ by the degree of delocalization of their electrons. We present geometries and electron detachment energies computed at a correlated level of theory. The results point to a classification of the eight dianions in three distinct groups of electronic stability. We are able to explain this grouping by a simple resonance structure picture, which demonstrates why the dianions with more delocalized electrons are less stable.
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Affiliation(s)
- Sven Feuerbacher
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany.
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