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Dissociation dynamics of highly excited molecules: Theory and Experiment

Oghbaie, Shabnam LU (2017)
Abstract
This thesis presents studies on dissociation of two model molecules: Butadiene and Cyclopropane. Tunable synchrotron radiation was used to ionize or excite the molecules in the gas phase, and the momentum correlation of the resulting fragment ions were measured using a 3D momenta coincident ion spectroscopy. The experimental results were interpreted with the aid of ab-initio quantum calculation. This allows us to gain insight into the fundamental processes behind the molecular dissociation, that how correlated electronic and nuclear dynamics drive molecular dissociation.
Tunable XUV-radiation was used to doubly ionize molecules to different states.
By Comparing experimental and theoretical values for appearance energy and kinetic... (More)
This thesis presents studies on dissociation of two model molecules: Butadiene and Cyclopropane. Tunable synchrotron radiation was used to ionize or excite the molecules in the gas phase, and the momentum correlation of the resulting fragment ions were measured using a 3D momenta coincident ion spectroscopy. The experimental results were interpreted with the aid of ab-initio quantum calculation. This allows us to gain insight into the fundamental processes behind the molecular dissociation, that how correlated electronic and nuclear dynamics drive molecular dissociation.
Tunable XUV-radiation was used to doubly ionize molecules to different states.
By Comparing experimental and theoretical values for appearance energy and kinetic energy released of the dissociation channels, electronic gateway state of each dissociation channels were identified. By analysing the momentum vector of ion pairs as a function of photon energy and internal energy sharing in the dissociative double ionization channels, mechanisms of double ionization (direct or indirect) processes were investigated. The studies shed light on the electron-electron and electron-nuclear correlation effects in the molecules.
Tunable X-rays were used to selectively excite a localized core electron to different valence orbitals, and the subsequent autoionization and dissociation processes were studied by analysing the correlated momentum of ionic fragments. In butadiene, the dependence of molecular dissociation on the initial site of core-hole was studied for the chemically shifted terminal and central carbon core-electrons excitation.
In cyclopropane the dependence of molecular dissociation on the changing of the molecular bonding character was studied for different core-to-valence excitation.
The studies indicated the importance of the ultra-fast nuclear dynamics initiated
within a few femtosecond core-hole lifetime changing the picture of electron-electron correlation in autoionization processes and leading to specific dissociation channels. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Simon, Marc, Laboratoire de Chimie Physique – Matière et Rayonnement (LCPMR), Université Pierre et Marie CURIE, Paris, France
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Molecular dissociation, core-electron excitation, double ionization, femtoseconds molecular dynamics, Isomerization, symmetry breaking, momentum imaging, site-selective dissociation, butadiene, cyclopropane, nuclear dynamics, Auger decay
pages
120 pages
publisher
Lund University, Faculty of Science, Department of Physics, Division of Synchrotron Radiation Research
defense location
Rydberg lecture hall, Department of Physics, Sölvegatan 14A, Lund
defense date
2017-05-19 13:15
ISBN
978-91-7753-263-7
978-91-7753-262-0
language
English
LU publication?
yes
id
f5d90cd0-24cc-4e91-9638-145ee6567423
date added to LUP
2017-04-10 13:33:58
date last changed
2017-04-27 18:35:03
@phdthesis{f5d90cd0-24cc-4e91-9638-145ee6567423,
  abstract     = {This thesis presents studies on dissociation of two model molecules: Butadiene and Cyclopropane. Tunable synchrotron radiation was used to ionize or excite the molecules in the gas phase, and the momentum correlation of the resulting fragment ions were measured using a 3D momenta coincident ion spectroscopy. The experimental results were interpreted with the aid of ab-initio quantum calculation. This allows us to gain insight into the fundamental processes behind the molecular dissociation, that how correlated electronic and nuclear dynamics drive molecular dissociation.<br/>Tunable XUV-radiation was used to doubly ionize molecules to different states.<br/>By Comparing experimental and theoretical values for appearance energy and kinetic energy released of the dissociation channels, electronic gateway state of each dissociation channels were identified. By analysing the momentum vector of ion pairs as a function of photon energy and internal energy sharing in the dissociative double ionization channels, mechanisms of double ionization (direct or indirect) processes were investigated. The studies shed light on the electron-electron and electron-nuclear correlation effects in the molecules.<br/>Tunable X-rays were used to selectively excite a localized core electron to different valence orbitals, and the subsequent autoionization and dissociation processes were studied by analysing the correlated momentum of ionic fragments. In butadiene, the dependence of molecular dissociation on the initial site of core-hole was studied for the chemically shifted terminal and central carbon core-electrons excitation.<br/>In cyclopropane the dependence of molecular dissociation on the changing of the molecular bonding character was studied for different core-to-valence excitation.<br/>The studies indicated the importance of the ultra-fast nuclear dynamics initiated<br/>within a few femtosecond core-hole lifetime changing the picture of electron-electron correlation in autoionization processes and leading to specific dissociation channels.},
  author       = {Oghbaie, Shabnam},
  isbn         = {978-91-7753-263-7},
  keyword      = {Molecular dissociation,core-electron excitation,double ionization,femtoseconds molecular dynamics,Isomerization,symmetry breaking,momentum imaging,site-selective dissociation,butadiene,cyclopropane,nuclear dynamics,Auger decay},
  language     = {eng},
  pages        = {120},
  publisher    = {Lund University, Faculty of Science, Department of Physics, Division of Synchrotron Radiation Research},
  school       = {Lund University},
  title        = {Dissociation dynamics of highly excited molecules: Theory and Experiment},
  year         = {2017},
}