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
The role of knockout driven fragmentation in collision with isolated complex molecular systems
Stockholm University, Faculty of Science, Department of Physics.ORCID iD: 0000-0003-0471-3844
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This licentiate thesis covers results from collision induced dissociation (CID) experiments of Polycyclic Aromatic Hydrocarbons (PAHs), hydrogentated PAHs (HPAHs) and porphyrins. PAHs and HPAHs are believed to play key roles in the evolution of complex molecules in space, while porphyrins are essential for various functions in living organisms. The experiments were carried out in the Electrospray Ion Source Laboratory (EIS-LAB) at the Double ElectroStatic Ion-Ring ExpEriment (DESIREE) infrastructure, Stockholm University.  In these studies, molecular ions collide with neutral targets at center-of-mass energies from a few tens to a few hundreds of eV. In this energy regime, fragmentation is mainly driven by nuclear scattering processes (nuclear stopping) rather than by interactions with the molecular electronic clouds (electronic stopping). Thus, knockout of single heavy atoms from the molecule in prompt billiard-ball type collision processes may occur in competition with statistical fragmentation processes in which the excitation energy is redistributed across all degrees of freedom before the decay. In this thesis, we have investigated the importance of knockout driven fragmentation processes in a series of experiments with markedly different molecular structures ranging from pure sp2-hybridized to pure sp3-hybridized systems. The experiments are interpreted in view of molecular structure and molecular dynamics simulations. These studies show that knockout processes are important for any molecular system, but they are in general difficult to isolate by means of mass spectrometric techniques. We have seen clear fingerprints of single carbon-atom loss in the collision experiments for PAHs and porphyrins. In contrast, in the case of the hydrogenated PAHs the fragmentation is dominated by the statistical loss of single carbon atoms due to their lower dissociation energy. We further report the threshold displacement energy for PAH, hydrogenated PAHs and porphyrin molecules--the key intrinsic property determining the cross section for prompt atom knockout.

Place, publisher, year, edition, pages
Stockholm: Stockholm University, 2018.
Keywords [en]
Knockout processes, PAHs, HPAHs, porphyrins
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-155257OAI: oai:DiVA.org:su-155257DiVA, id: diva2:1198266
Presentation
2018-05-09, FB42, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2019-06-11 Created: 2018-04-17 Last updated: 2019-06-11Bibliographically approved

Open Access in DiVA

No full text in DiVA

Search in DiVA

By author/editor
Giacomozzi, Linda
By organisation
Department of Physics
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 12 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