Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Formation of H2 from internally heated polycyclic aromatic hydrocarbons: Excitation energy dependence
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Show others and affiliations
2015 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, no 14, 144305Article in journal (Refereed) Published
Abstract [en]

We have investigated the effectiveness of molecular hydrogen (H-2) 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 H-2 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 H-2 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 H-2-formation rates.

Place, publisher, year, edition, pages
2015. Vol. 142, no 14, 144305
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-117139DOI: 10.1063/1.4917021ISI: 000352969600023OAI: oai:DiVA.org:su-117139DiVA: diva2:810834
Available from: 2015-05-08 Created: 2015-05-08 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Ions colliding with molecules and molecular clusters: fragmentation and growth processes
Open this publication in new window or tab >>Ions colliding with molecules and molecular clusters: fragmentation and growth processes
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this work we will discuss fragmentation and molecular growth processes in collisions of Polycyclic Aromatic Hydrocarbon (PAH) molecules, fullerenes, or their clusters with atoms or atomic ions. Simple collision models as well as molecular structure calculations are used to aid the interpretations of the present and other experimental results. Fragmentation features at center-of-mass collision energies around 10 keV are dominated by interactions between the fast ion/atom and the electron cloud in the molecules/clusters (electronic stopping processes). This electronic excitation energy is rapidly distributed on the vibrational degrees of freedom of the molecule or of the molecules in a cluster and may result in fragmentation. Here, the fragmentation is statistical and favors the lowest-energy dissociation channels which are losses of intact molecules from clusters, H- and C2H2-losses from isolated PAHs, and C2-loss from fullerene monomers. We will also discuss the possibility of formation of molecular H2 direct from native PAHs which reach high enough energies when interacting with ions, electrons, or photons.

For the experiments at lower center of mass collision energies (~100 eV) a single atom may be knocked out in close atom-atom interaction. Such non-statistical fragmentation are due to nuclear stopping processes and gives highly reactive fragments which may form covalent bonds with other molecules in a cluster on very short time scales (picoseconds). This process may be important when considering the formation of new species. For collision between 12 keV Ar2+ and clusters of pyrene (C16H10) molecules, new molecules, e.g. C17H10+, C30H18+, C31H19+, etc are detected. We also observe molecular fusion processes for He and Ar ions colliding with clusters of C60 molecules. These and related molecular fusion processes may play a key role for understanding molecular growth processes under certain astrophysical conditions.

Place, publisher, year, edition, pages
Stockholm University, 2015. 38 p.
Keyword
PAH, H2, C60, fragmentation
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-117114 (URN)978-91-7649-063-1 (ISBN)
Public defence
2015-06-11, FD5, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2015-05-20 Created: 2015-05-07 Last updated: 2015-05-22Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Chen, TaoGatchell, MichaelStockett, Mark H.Schmidt, Henning T.Cederquist, HenningZettergren, Henning
By organisation
Department of Physics
In the same journal
Journal of Chemical Physics
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 28 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf