Change search
ReferencesLink to record
Permanent link

Direct link
Knockout driven reactions in complex molecules and their clusters
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
(English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455Article in journal (Refereed) Submitted
Abstract [en]

Energetic ions lose some of their kinetic energies when interacting with electrons or nuclei in matter. Here, we discuss combined experimental and theoretical studies on such impulse driven reactions in Polycyclic Aromatic Hydrocarbons (PAHs), fullerenes, and pure or mixed clusters of these molecules. These studies show that the nature of excitation is important for how complex molecular systems respond to ion/atom impact. Rutherford-like nuclear scattering processes may lead to prompt atom knockout and formation of highly reactive fragments, while heating of the molecular electron clouds in general lead to formation of more stable and less reactive fragments. In this topical review, we focus on recent studies of knockout driven reactions, and present new calculations of the angular dependent threshold (displacement) energies for such processes in PAHs. The so formed fragments may efficiently form covalent bonds with neighboring molecules in clusters. These unique molecular growth processes may be important in astrophysical environments such as low velocity shock waves. 

National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-129578OAI: oai:DiVA.org:su-129578DiVA: diva2:923334
Available from: 2016-04-26 Created: 2016-04-26 Last updated: 2016-04-26Bibliographically approved
In thesis
1. Molecular Hole Punching: Impulse Driven Reactions in Molecules and Molecular Clusters
Open this publication in new window or tab >>Molecular Hole Punching: Impulse Driven Reactions in Molecules and Molecular Clusters
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

When molecules are excited by photons or energetic particles, they will cool through the emission of photons, electrons, or by fragmenting. Such processes are often thermal as they occur after the excitation energy has been redistributed across all degrees-of-freedom in the system. Collisions with atoms or ions may also lead to ultrafast fragmentation in Rutherford-like scattering processes, where one or several atoms can literally be knocked out of the molecule by the incoming projectile before the energy can be completely redistributed. The resulting fragmentation pathways can in such knockout processes be very different from those in thermal processes.

This thesis covers extensive studies of collisions between ions/atoms and isolated Polycyclic Aromatic Hydrocarbon (PAH) molecules, isolated fullerene molecules, or clusters of these. The high stabilities and distinct fragmentation channels make these types of molecules excellent test cases for characterizing knockout-driven fragmentation and the reactions that these processes can lead to. I will present experimental measurements for a wide range of energies and compare them with my own molecular dynamics simulations and quantum chemical calculations. In this thesis, I present an in-depth study of the role of knockout in the energetic processing of molecules and clusters. The competition between knockout and thermally driven fragmentation is discussed in detail.

Knockout-driven fragmentation is shown to result in exotic fragments that are far more reactive than the intact parent molecules or fragments from thermal processes. When such reactive species are formed within molecular clusters efficient molecular growth can take place on sub-picosecond timescales. The cluster environments are crucial here because they protect the newly formed molecules by absorbing excess energy. This is a possible pathway for the growth of large PAHs, fullerenes, and similar carbonaceous complexes found in, for instance, the interstellar medium.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2016. 74 p.
Keyword
PAHs, Fullernes, Reactions, Clusters, Interstellar Medium, Fragmentation, Non-Statistical Fragmentation, Collisions, Experiments, Molecular Dynamics, Density Functional Theory
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-129523 (URN)978-91-7649-436-3 (ISBN)
Public defence
2016-06-10, FB42, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 1: Submitted.

Available from: 2016-05-18 Created: 2016-04-25 Last updated: 2016-05-19Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Gatchell, MichaelZettergren, Henning
By organisation
Department of Physics
In the same journal
Journal of Physics B: Atomic, Molecular and Optical Physics
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 21 hits
ReferencesLink to record
Permanent link

Direct link