| 1. |
- Seitz, Fabian, et al.
(author)
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Ions colliding with clusters of fullerenes-Decay pathways and covalent bond formations
- 2013
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 139:3
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Journal article (peer-reviewed)abstract
- We report experimental results for the ionization and fragmentation of weakly bound van der Waals clusters of n C-60 molecules following collisions with Ar2+, He2+, and Xe20+ at laboratory kinetic energies of 13 keV, 22.5 keV, and 300 keV, respectively. Intact singly charged C-60 monomers are the dominant reaction products in all three cases and this is accounted for by means of Monte Carlo calculations of energy transfer processes and a simple Arrhenius-type [C-60](n)(+) -> C-60(+) + (n - 1)C-60 evaporation model. Excitation energies in the range of only similar to 0.7 eV per C-60 molecule in a [C-60](13)(+) cluster are sufficient for complete evaporation and such low energies correspond to ion trajectories far outside the clusters. Still we observe singly and even doubly charged intact cluster ions which stem from even more distant collisions. For penetrating collisions the clusters become multiply charged and some of the individual molecules may be promptly fragmented in direct knock-out processes leading to efficient formations of new covalent systems. For Ar2+ and He2+ collisions, we observe very efficient C-119(+) and C-118(+) formation and molecular dynamics simulations suggest that they are covalent dumb-bell systems due to bonding between C-59(+) or C-58(+) and C-60 during cluster fragmentation. In the Ar2+ case, it is possible to form even smaller C-120-2m(+) molecules (m = 2-7), while no molecular fusion reactions are observed for the present Xe20+ collisions.
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| 2. |
- Zettergren, Henning, et al.
(author)
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Bond formation in C-59(+)-C-60 collisions
- 2014
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In: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP).
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Conference paper (peer-reviewed)abstract
- In this work, we show that keV-ions are able to remove single carbon atoms from individual fullerenes in clusters of C-60 molecules. This very efficiently leads to the formation of exotic q dumbbell molecules through secondary C-59(+) - C-60 collisions within the fragmenting cluster. Such molecular fusion processes are inherently different from those induced by photons where only products with even numbers of carbon atoms are observed. Thus, ion collisions ignite unique and hitherto overlooked secondary reactions in small aggregates of matter. This relates to the question on how complex molecules may form in e.g. space.
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| 3. |
- Zettergren, Henning, et al.
(author)
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Formation of dumb-bell C118 and C119 inside clusters of C60 -molecules
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Journal article (peer-reviewed)abstract
- We report highly selective covalent bond-modifications in collisions between keV alpha particles and van der Waals clusters of C60-fullerenes. Surprisingly, C119+ and C118+ are the dominant molecular fusion products. We use Molecular Dynamics simulations to show that C59+ and C58+ ions - effectively produced in prompt knock-out processes with He2+ - react rapidly with C60 to form dumb-bell C119+ and C118+ . 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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| 4. |
- Zettergren, Henning, et al.
(author)
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Formations of Dumbbell C-118 and C-119 inside Clusters of C-60 Molecules by Collision with alpha Particles
- 2013
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:18
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Journal article (peer-reviewed)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 He2+-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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| 5. |
- Zettergren, Henning, et al.
(author)
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Roadmap on dynamics of molecules and clusters in the gas phase
- 2021
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In: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 75:5
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Journal article (peer-reviewed)abstract
- This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty order of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity from the smallest (diatomic) molecules to clusters and nanoparticles. Combining some of these techniques opens up new avenues to unravel hitherto unexplored reaction pathways and mechanisms, and to establish their significance in, e.g. radiotherapy and radiation damage on the nanoscale, astrophysics, astrochemistry and atmospheric science.
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| 6. |
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| 7. |
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| 8. |
- Gatchell, Michael, et al.
(author)
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Non-statistical fragmentation of PAHs and fullerenes in collisions with atoms
- 2014
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In: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806 .- 1873-2798. ; 365, s. 260-265
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Journal article (peer-reviewed)abstract
- Non-statistical fragmentation processes may be important when Polycyclic Aromatic Hydrocarbon molecules (PAHs), fullerenes, or other large complex molecules collide with atoms and atomic ions. For collisions with hydrogen or helium this occurs for center-of-mass energies between a few tens to a few hundreds of electron volts and typically results in losses of single atoms. In such processes one forms much more reactive fragments than in statistical fragmentation, which instead are dominated by losses of C2- or C2H2-molecules (H-atoms) from fullerenes and PAHs, respectively. An enhanced reactivity has recently been demonstrated for van der Waals clusters of C60 molecules where prompt knockouts of single C-atoms from one of the fullerenes yield highly reactive C59+ fragments, which easily form covalent bonds with a C60 molecule inside the clusters
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| 9. |
- Giacomozzi, Linda, et al.
(author)
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Decay pathways for protonated and deprotonated adenine molecules
- 2019
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 151:4
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Journal article (peer-reviewed)abstract
- We have measured fragment mass spectra and total destruction cross sections for protonated and deprotonated adenine following collisions with He at center-of-mass energies in the 20-240 eV range. Classical and ab initio molecular dynamics simulations are used to provide detailed information on the fragmentation pathways and suggest a range of alternative routes compared to those reported in earlier studies. These new pathways involve, for instance, losses of HNC molecules from protonated adenine and losses of NH2 or C3H2N2 from deprotonated adenine. The present results may be important to advance the understanding of how biomolecules may be formed and processed in various astrophysical environments.
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| 10. |
- Ha, Dang Trinh, et al.
(author)
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Fragmentation Dynamics of Doubly Charged Methionine Phase
- 2014
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In: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 118:8, s. 1374-1383
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Journal article (peer-reviewed)abstract
- The dependence of the fragmentation of doubly charged gas-phase methionine (C5H11NO2S) on the electronic-state character of the parent ion is studied experimentally by energy-resolved electron ion-ion coincidence spectroscopy. The parent dication electronic states are populated by Auger transitions following site-specific sulfur 2p core ionization. Two fragmentation channels are observed to be strongly dependent on the electronic states with vacancies in weakly bound molecular orbitals. All-electron calculations are applied to assign doubly charged final states of sulfur 2p core ionized methionine. In addition, the Car-Parrinello method is applied to model fragmentation dynamics of doubly charged methionine molecules with various initial temperatures to understand the typical characteristics of the molecular dissociation and partly to support the interpretation of experimental data.
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