1
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Electron Emission Cross Section from Methane under 250 keV Proton Impact. ATOMS 2023. [DOI: 10.3390/atoms11030049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023] Open
Abstract
We measure double differential cross sections (DDCS) of electrons emitted from CH4 molecules in collisions with 250 keV protons. The projectile ions are obtained from a 400 kV electron cyclotron resonance-based ion accelerator (ECRIA). We study the energy and angular distributions of the electron DDCS. The observed double and single differential and the total cross section are compared with the state-of-the-art continuum distorted wave eikonal initial state (CDW-EIS) model predictions. Two different approaches are used considering the different target descriptions: complete neglect of differential overlap (CNDO) and molecular orbital (MO) approximations. The MO model uses two different scaling parameters (d = 0.7 and 1.0). In the energy distribution of the DDCS, the carbon KLL Auger line is also observed at 240 eV. The single differential cross section (SDCS) and total cross section (TCS) are derived. Both the MO-based CDW-EIS models are in good agreement with the experimental results; however, the CNDO approach overestimates the data.
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2
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Zamith S, Kassem A, L'Hermite JM, Joblin C. Water Attachment onto Size-Selected Cationic Pyrene Clusters. J Phys Chem A 2022; 126:3696-3707. [PMID: 35670699 DOI: 10.1021/acs.jpca.2c02195] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report measurements of the attachment rates of water molecules onto mass-selected cationic pyrene clusters for size from n = 4 to 13 pyrene units and for different collision energies. Comparison of the attachment rates with the collision rates measured in collision-induced dissociation experiments provides access to the values of the sticking coefficient. The strong dependence of the attachment rates on size and collision energy is rationalized through a model in which we use a Langevin-type collision rate and adjust on experimental data the statistical dissociation rate of the water molecule from the cluster after attachment. This allows us to extrapolate our results to the conditions of isolation and long time scales encountered in astrophysical environments.
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Affiliation(s)
- Sébastien Zamith
- Laboratoire Collision Agrégats Réactivité (LCAR/IRSAMC), UMR5589, Université de Toulouse III - Paul Sabatier and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Ali Kassem
- Laboratoire Collision Agrégats Réactivité (LCAR/IRSAMC), UMR5589, Université de Toulouse III - Paul Sabatier and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France.,Institut de Recherche en Astrophysique et Planétologie (IRAP), UMR5277, Université de Toulouse III - Paul Sabatier, CNRS, CNES, 9 avenue du Colonel Roche, F-31028 Toulouse, France
| | - Jean-Marc L'Hermite
- Laboratoire Collision Agrégats Réactivité (LCAR/IRSAMC), UMR5589, Université de Toulouse III - Paul Sabatier and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie (IRAP), UMR5277, Université de Toulouse III - Paul Sabatier, CNRS, CNES, 9 avenue du Colonel Roche, F-31028 Toulouse, France
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3
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4
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Zamith S, L’Hermite JM, Dontot L, Zheng L, Rapacioli M, Spiegelman F, Joblin C. Threshold collision induced dissociation of pyrene cluster cations. J Chem Phys 2020; 153:054311. [PMID: 32770931 PMCID: PMC7116296 DOI: 10.1063/5.0015385] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report threshold collision induced dissociation experiments on cationic pyrene clusters, for sizes n = 2-6. Fragmentation cross sections are recorded as a function of the collision energy and analyzed with a statistical model. This model can account for the dissociation cascades and provides values for the dissociation energies. These values, of the order of 0.7 eV-1 eV, are in excellent agreement with those previously derived from thermal evaporation. They confirm the charge resonance stability enhancement predicted by theoretical calculations. In addition, remarkable agreement is obtained with theoretical predictions for the two smaller sizes n = 2 and 3. For the larger sizes, the agreement remains good, although the theoretical values obtained for the most stable structures are systematically higher by 0.2 eV. This offset could be attributed to approximations in the calculations. Still, there is an indication in the results of an incomplete description of the role of isomerization and/or direct dissociation upon collisions. Finally, by-product clusters containing dehydrogenated species are found to dissociate at energies comparable to the non-dehydrogenated ones, which shows no evidence for covalent bonds within the clusters.
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Affiliation(s)
- Sébastien Zamith
- Laboratoire Collision Agrégats Réactivité (LCAR/IRSAMC), UMR5589, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Jean-Marc L’Hermite
- Laboratoire Collision Agrégats Réactivité (LCAR/IRSAMC), UMR5589, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Léo Dontot
- Laboratoire de Chimie et Physique Quantique (LCPQ/IRSAMC), UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Linjie Zheng
- Laboratoire de Chimie et Physique Quantique (LCPQ/IRSAMC), UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantique (LCPQ/IRSAMC), UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Fernand Spiegelman
- Laboratoire de Chimie et Physique Quantique (LCPQ/IRSAMC), UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie (IRAP), UMR5277, Université de Toulouse (UPS) and CNRS, 9 avenue du Colonel Roche, F-31028 Toulouse, France
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5
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Unravelling molecular interactions in uracil clusters by XPS measurements assisted by ab initio and tight-binding simulations. Sci Rep 2020; 10:13081. [PMID: 32753713 PMCID: PMC7403593 DOI: 10.1038/s41598-020-69947-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/21/2020] [Indexed: 12/13/2022] Open
Abstract
The C, N and O 1s XPS spectra of uracil clusters in the gas phase have been measured. A new bottom-up approach, which relies on computational simulations starting from the crystallographic structure of uracil, has been adopted to interpret the measured spectra. This approach sheds light on the different molecular interactions (H-bond, π-stacking, dispersion interactions) at work in the cluster and provides a good understanding of the observed XPS chemical shifts with respect to the isolated molecule in terms of intramolecular and intermolecular screening occurring after the core–hole ionization. The proposed bottom-up approach, reasonably expensive in terms of computational resources, has been validated by finite-temperature molecular dynamics simulations of clusters composed of up to fifty molecules.
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6
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Milosavljević AR, Jänkälä K, Ranković ML, Canon F, Bozek J, Nicolas C, Giuliani A. Oxygen K-shell spectroscopy of isolated progressively solvated peptide. Phys Chem Chem Phys 2020; 22:12909-12917. [DOI: 10.1039/d0cp00994f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
X-ray spectroscopy of an isolated controllably hydrated peptide: core excitation of the first solvation shell enhances peptide backbone fragmentation.
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Affiliation(s)
| | - Kari Jänkälä
- Nano and Molecular Systems Research Unit
- University of Oulu
- 90014 Oulu
- Finland
| | | | - Francis Canon
- Centre des Sciences du Goût et de l’Alimentation
- CNRS
- INRAE
- Université de Bourgogne Franche-Comté
- France
| | - John Bozek
- SOLEIL, l’Orme des Merisiers
- 91192 Gif sur Yvette Cedex
- France
| | | | - Alexandre Giuliani
- SOLEIL, l’Orme des Merisiers
- 91192 Gif sur Yvette Cedex
- France
- INRAE
- UAR1008
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7
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Coulomb Explosion of Polycyclic Aromatic Hydrocarbons Induced by Heavy Cosmic Rays: Carbon Chains Production Rates. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-4357/ab584f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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8
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Zamitha S, Ji MC, L’Hermite JM, Joblin C, Dontot L, Rapacioli M, Spiegelman F. Thermal evaporation of pyrene clusters. J Chem Phys 2019; 151:194303. [PMID: 31757155 PMCID: PMC6908449 DOI: 10.1063/1.5100264] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This work presents a study of the thermal evaporation and stability of pyrene (C16H10)n clusters. Thermal evaporation rates of positively charged mass-selected clusters are measured for sizes in the range n = 3-40 pyrene units. The experimental setup consists of a gas aggregation source, a thermalization chamber, and a time of flight mass spectrometer. A microcanonical Phase Space Theory (PST) simulation is used to determine the dissociation energies of pyrene clusters by fitting the experimental breakdown curves. Calculations using the Density Functional based Tight Binding combined with a Configuration Interaction (CI-DFTB) model and a hierarchical optimization scheme are also performed in the range n = 2-7 to determine the harmonic frequencies and a theoretical estimation of the dissociation energies. The frequencies are used in the calculations of the density of states needed in the PST simulations, assuming an extrapolation scheme for clusters larger than 7 units. Using the PST model with a minimal set of adjustable parameters, we obtain good fits of the experimental breakdown curves over the full studied size range. The approximations inherent to the PST simulation and the influence of the used parameters are carefully estimated. The derived dissociation energies show significant variations over the studied size range. Compared with neutral clusters, significantly higher values of the dissociation energies are obtained for the smaller sizes and attributed to charge resonance in line with CI-DFTB calculations.
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Affiliation(s)
- Sébastien Zamitha
- Laboratoire Collisions Agrégats Réactivité (LCAR/IRSAMC) UMR5589, Université de Toulouse and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Ming-Chao Ji
- Institut de Recherche en Astrophysique et Planétologie (IRAP) UMR5277, Université de Toulouse, CNRS, CNES, 9 avenue du Colonel Roche, F-31028 Toulouse, France
| | - Jean-Marc L’Hermite
- Laboratoire Collisions Agrégats Réactivité (LCAR/IRSAMC) UMR5589, Université de Toulouse and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Christine Joblin
- Institut de Recherche en Astrophysique et Planétologie (IRAP) UMR5277, Université de Toulouse, CNRS, CNES, 9 avenue du Colonel Roche, F-31028 Toulouse, France
| | - Léo Dontot
- Institut de Recherche en Astrophysique et Planétologie (IRAP) UMR5277, Université de Toulouse, CNRS, CNES, 9 avenue du Colonel Roche, F-31028 Toulouse, France
- Laboratoire de Chimie et Physique Quantiques (LCPQ/IRSAMC) UMR5626, Université de Toulouse and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantiques (LCPQ/IRSAMC) UMR5626, Université de Toulouse and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Fernand Spiegelman
- Laboratoire de Chimie et Physique Quantiques (LCPQ/IRSAMC) UMR5626, Université de Toulouse and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
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9
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Dontot L, Spiegelman F, Rapacioli M. Structures and Energetics of Neutral and Cationic Pyrene Clusters. J Phys Chem A 2019; 123:9531-9543. [PMID: 31589446 PMCID: PMC6917508 DOI: 10.1021/acs.jpca.9b07007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The low energy structures of neutral and cationic pyrene clusters containing up to seven molecules are searched through a global exploration scheme combining parallel tempering Monte Carlo algorithm and local quenches. The potential energies are computed at the density functional based tight binding level for neutrals and configuration interaction density functional based tight binding for cations in order to treat properly the charge resonance. New simplified versions of these schemes are also presented and used during the global exploration. Neutral clusters are shown to be made of compact assemblies of sub-blocs containing up to three units whereas cations present a charged dimer or trimer core surrounded by neutral units. The structural features of the clusters are analyzed and correlated for the cation with the charge distribution. The stability of clusters is also discussed in terms of cohesive and evaporation energies. Adiabatic and vertical ionization potentials are also discussed.
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Affiliation(s)
- Léo Dontot
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Fernand Spiegelman
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantiques LCPQ/IRSAMC, UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
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10
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West BJ, Lesniak L, Mayer PM. Why Do Large Ionized Polycyclic Aromatic Hydrocarbons Not Lose C2H2? J Phys Chem A 2019; 123:3569-3574. [DOI: 10.1021/acs.jpca.9b01879] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Brandi J. West
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada K1N 6N5
| | - Lukas Lesniak
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada K1N 6N5
| | - Paul M. Mayer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada K1N 6N5
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11
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Mahmoodi-Darian M, Raggl S, Renzler M, Goulart M, Huber SE, Mauracher A, Scheier P, Echt O. Doubly charged coronene clusters-Much smaller than previously observed. J Chem Phys 2018; 148:174303. [PMID: 29739220 DOI: 10.1063/1.5028393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The smallest doubly charged coronene cluster ions reported so far, Cor152+, were produced by charge exchange between bare coronene clusters and He2+ [H. A. B. Johansson et al., Phys. Rev. A 84, 043201 (2011)]. These dications are at least five times larger than the estimated Rayleigh limit, i.e., the size at which the activation barrier for charge separation vanishes. Such a large discrepancy is unheard of for doubly charged atomic or molecular clusters. Here we report the mass spectrometric observation of doubly charged coronene trimers, produced by electron ionization of helium nanodroplets doped with coronene. The observation implies that Cor32+ features a non-zero fission barrier too large to overcome under the present experimental conditions. The height of the barriers for the dimer and trimer has been estimated by means of density functional theory calculations. A sizeable barrier for the trimer has been revealed in agreement with the experimental findings.
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Affiliation(s)
| | - Stefan Raggl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Michael Renzler
- 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
| | - Stefan E Huber
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andreas Mauracher
- 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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12
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Joblin C, Dontot L, Garcia GA, Spiegelman F, Rapacioli M, Nahon L, Parneix P, Pino T, Bréchignac P. Size Effect in the Ionization Energy of PAH Clusters. J Phys Chem Lett 2017; 8:3697-3702. [PMID: 28742357 PMCID: PMC5545758 DOI: 10.1021/acs.jpclett.7b01546] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 07/25/2017] [Indexed: 05/12/2023]
Abstract
We report the first experimental measurement of the near-threshold photoionization spectra of polycyclic aromatic hydrocarbon clusters made of pyrene C16H10 and coronene C24H12, obtained using imaging photoelectron-photoion coincidence spectrometry with a VUV synchrotron beamline. The experimental results of the ionization energy are compared to calculated ones obtained from simulations using dedicated electronic structure treatment for large ionized molecular clusters. Experiment and theory consistently find a decrease of the ionization energy with cluster size. The inclusion of temperature effects in the simulations leads to a lowering of this energy and to quantitative agreement with the experiment. In the case of pyrene, both theory and experiment show a discontinuity in the IE trend for the hexamer. This work demonstrates the ability of the models to describe the electronic structure of PAH clusters and suggests that these species are ionized in astronomical environments where they are thought to be present.
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Affiliation(s)
- C. Joblin
- IRAP, Université de
Toulouse, CNRS, UPS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| | - L. Dontot
- IRAP, Université de
Toulouse, CNRS, UPS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| | - G. A. Garcia
- Synchrotron
SOLEIL, L’Orme
des Merisiers, 91192 Gif sur Yvette Cedex, France
| | - F. Spiegelman
- Laboratoire
de Chimie et Physique Quantiques LCPQ/IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, 31062 Toulouse, France
| | - M. Rapacioli
- Laboratoire
de Chimie et Physique Quantiques LCPQ/IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, 31062 Toulouse, France
| | - L. Nahon
- Synchrotron
SOLEIL, L’Orme
des Merisiers, 91192 Gif sur Yvette Cedex, France
| | - P. Parneix
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ Paris
Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - T. Pino
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ Paris
Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - P. Bréchignac
- Institut
des Sciences Moléculaires d’Orsay, CNRS, Univ Paris
Sud, Université Paris-Saclay, F-91405 Orsay, France
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13
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Differential electron emission from polycyclic aromatic hydrocarbon molecules under fast ion impact. Sci Rep 2017; 7:5560. [PMID: 28717160 PMCID: PMC5514085 DOI: 10.1038/s41598-017-05149-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/24/2017] [Indexed: 11/17/2022] Open
Abstract
Interaction between polycyclic aromatic hydrocarbon (PAH) molecule and energetic ion is a subject of interest in different areas of modern physics. Here, we present measurements of energy and angular distributions of absolute double differential electron emission cross section for coronene (C24H12) and fluorene (C13H10) molecules under fast bare oxygen ion impact. For coronene, the angular distributions of the low energy electrons are quite different from that of simpler targets like Ne or CH4, which is not the case for fluorene. The behaviour of the higher electron energy distributions for both the targets are similar to that for simple targets. In case of coronene, a clear signature of plasmon resonance is observed in the analysis of forward-backward angular asymmetry of low energy electron emission. For fluorene, such signature is not identified probably due to lower oscillator strength of plasmon compared to the coronene. The theoretical calculation based on the first-order Born approximation with correct boundary conditions (CB1), in general, reproduced the experimental observations qualitatively, for both the molecules, except in the low energy region for coronene, which again indicates the role of collective excitation. Single differential and total cross sections are also deduced. An overall comparative study is presented.
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14
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Colliding the hydrocarbon building blocks of astrochemical polycyclic aromatic hydrocarbons with 8 keV He+ and H2+ ions: Luminescence from methane, acetylene, benzene and naphthalene. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2016.11.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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PHOTO-STABILITY OF SUPER-HYDROGENATED PAHs DETERMINED BY ACTION SPECTROSCOPY EXPERIMENTS. ACTA ACUST UNITED AC 2016. [DOI: 10.3847/0004-637x/832/1/24] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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16
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Stockett MH, Gatchell M, Chen T, de Ruette N, Giacomozzi L, Wolf M, Schmidt HT, Zettergren H, Cederquist H. Threshold energies for single-carbon knockout from polycyclic aromatic hydrocarbons. J Phys Chem Lett 2015; 6:4504-4509. [PMID: 26523738 DOI: 10.1021/acs.jpclett.5b02080] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have measured absolute cross sections for ultrafast (femtosecond) single-carbon knockout from polycyclic aromatic hydrocarbon (PAH) cations as functions of He–PAH center-of-mass collision energy in the 10–200 eV range. Classical molecular dynamics (MD) simulations cover this range and extend up to 105 eV. The shapes of the knockout cross sections are well-described by a simple analytical expression yielding experimental and MD threshold energies of EthExp = 32.5 ± 0.4 eV and EthMD = 41.0 ± 0.3 eV, respectively. These are the first measurements of knockout threshold energies for molecules isolated in vacuo. We further deduce semiempirical (SE) and MD displacement energies, i.e., the energy transfers to the PAH molecules at the threshold energies for knockout, of TdispSE = 23.3 ± 0.3 eV and TdispMD = 27.0 ± 0.3 eV. The semiempirical results compare favorably with measured displacement energies for graphene (Tdisp = 23.6 eV).
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Affiliation(s)
- M H Stockett
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark
| | - M Gatchell
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - T Chen
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - N de Ruette
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - L Giacomozzi
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - M Wolf
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - H T Schmidt
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University , Stockholm SE-106 91, Sweden
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17
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Chen T, Gatchell M, Stockett MH, Delaunay R, Domaracka A, Micelotta ER, Tielens AGGM, Rousseau P, Adoui L, Huber BA, Schmidt HT, Cederquist H, Zettergren H. Formation of H2 from internally heated polycyclic aromatic hydrocarbons: excitation energy dependence. J Chem Phys 2015; 142:144305. [PMID: 25877576 DOI: 10.1063/1.4917021] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have investigated the effectiveness of molecular hydrogen (H2) formation from Polycyclic Aromatic Hydrocarbons (PAHs) which are internally heated by collisions with keV ions. The present and earlier experimental results are analyzed in view of molecular structure calculations and a simple collision model. We estimate that H2 formation becomes important for internal PAH temperatures exceeding about 2200 K, regardless of the PAH size and the excitation agent. This suggests that keV ions may effectively induce such reactions, while they are unlikely due to, e.g., absorption of single photons with energies below the Lyman limit. The present analysis also suggests that H2 emission is correlated with multi-fragmentation processes, which means that the [PAH-2H](+) peak intensities in the mass spectra may not be used for estimating H2-formation rates.
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Affiliation(s)
- T Chen
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - M Gatchell
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - R Delaunay
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - A Domaracka
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - E R Micelotta
- Université Paris Sud, Institut d'Astrophysique Spatiale, UMR 8617, 91405 Orsay, France
| | - A G G M Tielens
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
| | - P Rousseau
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - L Adoui
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - B A Huber
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen cedex 05, France
| | - H T Schmidt
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
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18
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Chen T, Gatchell M, Stockett MH, Alexander JD, Zhang Y, Rousseau P, Domaracka A, Maclot S, Delaunay R, Adoui L, Huber BA, Schlathölter T, Schmidt HT, Cederquist H, Zettergren H. Absolute fragmentation cross sections in atom-molecule collisions: scaling laws for non-statistical fragmentation of polycyclic aromatic hydrocarbon molecules. J Chem Phys 2015; 140:224306. [PMID: 24929387 DOI: 10.1063/1.4881603] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We present scaling laws for absolute cross sections for non-statistical fragmentation in collisions between Polycyclic Aromatic Hydrocarbons (PAH/PAH(+)) and hydrogen or helium atoms with kinetic energies ranging from 50 eV to 10 keV. Further, we calculate the total fragmentation cross sections (including statistical fragmentation) for 110 eV PAH/PAH(+) + He collisions, and show that they compare well with experimental results. We demonstrate that non-statistical fragmentation becomes dominant for large PAHs and that it yields highly reactive fragments forming strong covalent bonds with atoms (H and N) and molecules (C6H5). Thus nonstatistical fragmentation may be an effective initial step in the formation of, e.g., Polycyclic Aromatic Nitrogen Heterocycles (PANHs). This relates to recent discussions on the evolution of PAHNs in space and the reactivities of defect graphene structures.
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Affiliation(s)
- T Chen
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - M Gatchell
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - M H Stockett
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - J D Alexander
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - Y Zhang
- Department of Mathematics, Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
| | - P Rousseau
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 05, France
| | - A Domaracka
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 05, France
| | - S Maclot
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 05, France
| | - R Delaunay
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 05, France
| | - L Adoui
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 05, France
| | - B A Huber
- CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Basse-Normandie, bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 05, France
| | - T Schlathölter
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - H T Schmidt
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - H Cederquist
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
| | - H Zettergren
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden
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19
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Stockett MH, Gatchell M, Alexander JD, Bērziņš U, Chen T, Farid K, Johansson A, Kulyk K, Rousseau P, Støchkel K, Adoui L, Hvelplund P, Huber BA, Schmidt HT, Zettergren H, Cederquist H. Fragmentation of anthracene C14H10, acridine C13H9N and phenazine C12H8N2ions in collisions with atoms. Phys Chem Chem Phys 2014; 16:21980-7. [DOI: 10.1039/c4cp03293d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Reitsma G, Boschman L, Deuzeman MJ, González-Magaña O, Hoekstra S, Cazaux S, Hoekstra R, Schlathölter T. Deexcitation dynamics of superhydrogenated polycyclic aromatic hydrocarbon cations after soft-x-ray absorption. PHYSICAL REVIEW LETTERS 2014; 113:053002. [PMID: 25126915 DOI: 10.1103/physrevlett.113.053002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Indexed: 06/03/2023]
Abstract
We have investigated the response of superhydrogenated gas-phase coronene cations upon soft x-ray absorption. Carbon (1s)⟶π^{⋆} transitions were resonantly excited at hν=285 eV. The resulting core hole is then filled in an Auger decay process, with the excess energy being released in the form of an Auger electron. Predominantly highly excited dications are thus formed, which cool down by hydrogen emission. In superhydrogenated systems, the additional H atoms act as a buffer, quenching loss of native H atoms and molecular fragmentation. Dissociation and transition state energies for several H loss channels were computed by means of density functional theory. Using these energies as input into an Arrhenius-type cascade model, very good agreement with the experimental data is found. The results have important implications for the survival of polyaromatic hydrocarbons in the interstellar medium and reflect key aspects of graphene hydrogenation.
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Affiliation(s)
- G Reitsma
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - L Boschman
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands and Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen, The Netherlands
| | - M J Deuzeman
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - O González-Magaña
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - S Hoekstra
- Van Swinderen Institute, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - S Cazaux
- Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700AV Groningen, The Netherlands
| | - R Hoekstra
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - T Schlathölter
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
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21
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Paris C, Alcamí M, Martín F, Díaz-Tendero S. Multiple ionization and hydrogen loss from neutral and positively-charged coronene. J Chem Phys 2014; 140:204307. [DOI: 10.1063/1.4875805] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Seitz F, Zettergren H, Rousseau P, Wang Y, Chen T, Gatchell M, Alexander JD, Stockett MH, Rangama J, Chesnel JY, Capron M, Poully JC, Domaracka A, Méry A, Maclot S, Vizcaino V, Schmidt HT, Adoui L, Alcamí M, Tielens AGGM, Martín F, Huber BA, Cederquist H. Ions colliding with clusters of fullerenes—Decay pathways and covalent bond formations. J Chem Phys 2013; 139:034309. [DOI: 10.1063/1.4812790] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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23
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Zettergren H, Rousseau P, Wang Y, Seitz F, Chen T, Gatchell M, Alexander JD, Stockett MH, Rangama J, Chesnel JY, Capron M, Poully JC, Domaracka A, Méry A, Maclot S, Schmidt HT, Adoui L, Alcamí M, Tielens AGGM, Martín F, Huber BA, Cederquist H. Formations of dumbbell C118 and C119 inside clusters of C60 molecules by collision with α particles. PHYSICAL REVIEW LETTERS 2013; 110:185501. [PMID: 23683214 DOI: 10.1103/physrevlett.110.185501] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Indexed: 05/26/2023]
Abstract
We report highly selective covalent bond modifications in collisions between keV alpha particles and van der Waals clusters of C(60) fullerenes. Surprisingly, C(119)(+) and C(118)(+) are the dominant molecular fusion products. We use molecular dynamics simulations to show that C(59)(+) and C(58)(+) ions--effectively produced in prompt knockout processes with He(2+)--react rapidly with C(60) to form dumbbell C(119)(+) and C(118)(+). Ion impact on molecular clusters in general is expected to lead to efficient secondary reactions of interest for astrophysics. These reactions are different from those induced by photons.
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Affiliation(s)
- H Zettergren
- Department of Physics, Stockholm University, S-106 91 Stockholm, Sweden.
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Forsberg BO, Alexander JD, Chen T, Pettersson AT, Gatchell M, Cederquist H, Zettergren H. Ions interacting with planar aromatic molecules: Modeling electron transfer reactions. J Chem Phys 2013; 138:054306. [DOI: 10.1063/1.4790164] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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25
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Johansson HAB, Zettergren H, Holm AIS, Haag N, Nielsen SB, Wyer JA, Kirketerp MBS, Støchkel K, Hvelplund P, Schmidt HT, Cederquist H. Unimolecular dissociation of anthracene and acridine cations: The importance of isomerization barriers for the C2H2 loss and HCN loss channels. J Chem Phys 2011; 135:084304. [DOI: 10.1063/1.3626792] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Seitz F, Holm AIS, Zettergren H, Johansson HAB, Rosén S, Schmidt HT, Ławicki A, Rangama J, Rousseau P, Capron M, Maisonny R, Domaracka A, Adoui L, Méry A, Manil B, Huber BA, Cederquist H. Polycyclic aromatic hydrocarbon-isomer fragmentation pathways: Case study for pyrene and fluoranthene molecules and clusters. J Chem Phys 2011; 135:064302. [DOI: 10.1063/1.3622589] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Holm AIS, Johansson HAB, Cederquist H, Zettergren H. Dissociation and multiple ionization energies for five polycyclic aromatic hydrocarbon molecules. J Chem Phys 2011; 134:044301. [DOI: 10.1063/1.3541252] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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