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Electron Recombination with Small Molecular Ions
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

In this thesis I have theoretically studied electron recombination processes with small molecular ions.

In these kind of processes resonant states are involved. To calculate the potential energy for these states as a function of internuclear distance, structure calculations and scattering calculations have to be performed.

So far I have been studying the ion-pair formation with in electron recombination with H3+. The cross section for this process has been calculated using different kind of models, both a time dependent quantum mechanical and a semiclassical.

I have also studied the direct process of dissociative recombination of HF+. To calculate the total cross section for this process, we have performed wave packet propagation on thirty resonant states and summed up the individual cross sections for these states.

The cross sections for both these processes have a similar appearance to those measured experimentally in the ion storage ring CRYRING in Stockholm.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , iv, 33 p.
Series
Trita-BIO-Report, ISSN 1654-2312
Keyword [en]
dissociative recombination, ion-pair formation, resonant states, wave packet, molecular dynamics, electron scattering
National Category
Theoretical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-4375ISBN: 978-91-7178-681-4 (print)OAI: oai:DiVA.org:kth-4375DiVA: diva2:12015
Presentation
2007-05-31, FD41, Huvudbyggnaden, Roslagstullsbacken 21, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101103Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-11-03Bibliographically approved
List of papers
1. Ion-pair formation in electron recombination with H3+
Open this publication in new window or tab >>Ion-pair formation in electron recombination with H3+
2006 (English)In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, Vol. 364, no 1848, 2999-3005 p.Article in journal (Refereed) Published
Abstract [en]

The process of resonant ion-pair formation following electron collisions with H-3(+) is studied. The relevant diabatic potential energy surfaces and the electronic couplings between these surfaces are calculated. The reaction is then described using a time-dependent approach with wave packets propagating on the coupled potentials. In order to describe the reaction, it is found necessary to include at least two dimensions in the model. The effects of the Rydberg states on the cross-section for this process are discussed.

Keyword
ion-pair state, wave packet dynamics, H-3(+)
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-7101 (URN)10.1098/rsta.2006.1884 (DOI)000241921300012 ()2-s2.0-33751438760 (Scopus ID)
Note
QC 20101103Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-11-03Bibliographically approved
2. Electron collisions with H3+: ion-pair formation
Open this publication in new window or tab >>Electron collisions with H3+: ion-pair formation
2007 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 76, no 4Article in journal (Refereed) Published
Abstract [en]

The formation of the ion pair H-2(+)+ H- in electron recombination with H-3(+) is studied. The diabatic potentials and electronic couplings are extracted from ab initio electron scattering calculations as well as quantum chemistry calculations. In order to describe this reaction we include six coupled electronic states and propagate wave packets in two dimensions using the multiconfiguration time-dependent Hartree method. Also, the cross section for ion-pair formation in electron recombination with D-3(+) is calculated. The cross section for this isotopomer is found to be about a factor of 3 smaller than the cross section for H-3(+).

Keyword
dissociative recombination, states, h-3+, isotopomers, flux
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-7102 (URN)10.1103/PhysRevA.76.042703 (DOI)000250619700097 ()2-s2.0-34948818801 (Scopus ID)
Note
Uppdaterad från manuskript till artikel: 20101103. QC 20101103Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-11-03Bibliographically approved
3. Dissociative recombination of HF+
Open this publication in new window or tab >>Dissociative recombination of HF+
2008 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 78, no 2Article in journal (Refereed) Published
Abstract [en]

The direct mechanism of dissociative recombination of HF+ is studied using both time-dependent and time-independent methods, where the dynamics on 30 resonant states is explored. The relevant electronic states are calculated ab initio, by combining electron scattering calculations with multireference configuration interaction structure calculations. For collision energies between 0.04 and 10 eV, we obtain qualitative agreement with experiment. At 1.9 eV there is a sharp threshold in both the experimental and theoretical cross sections that can be explained by the opening of new asymptotic limits. The measured cross section below 0.04 eV is not reproduced due to the neglect of the electronic couplings between the neutral states. We examine the validity of the local approximation for treating autoionization from the resonant states included in this study.

Keyword
wave-packet, electronic-spectrum, hydrogen-fluoride, pair formation, molecule, photodissociation, transmission, formulation, reflection, dynamics
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-7103 (URN)10.1103/PhysRevA.78.022508 (DOI)000259263400081 ()
Note
Uppdaterad från manuskript till artikel: 20101103. QC 20101103Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-11-03Bibliographically approved

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