Gas phase molecular relaxation probed by synchrotron radiation experiments
Author
Summary, in English
This thesis presents experimental studies of gas phase molecular relaxation after excitation
with synchrotron photons in the 15-35 eV and in the 70-350 eV regions.
In the 15-35 eV region, molecular relaxation by neutral dissociation processes and non
Franck-Condon effects in N2 and O2 molecules have been studied by means of dispersed fluorescence
and photoelectron spectroscopy experimental techniques, respectively. From the dispersed
fluorescence data, excitation functions for the measured atomic fluorescence spectra have been
obtained. From the recorded photoelectron spectra vibrational branching ratios have been produced.
The results obtained reveal that Rydberg series and singly and doubly excited valence states of the
appropriate symmetry energetically accessible in the studied region and interactions between them
account for most of the observed effects in these two type of experiments.
In the 70-350 eV range, molecular relaxation processes resulting in fragmentation of CD4 and
SF6 after absorption of synchrotron light have been studied by energy resolved electron ion
coincidence technique using a multicoincidence experimental station developed by our group during
the last five years for such type of experiments. The coincidence measurements yielded mass spectra
from which information about the kinematics of the detected fragments has been deduced by means of
Monte Carlo simulations of the experimental peak shapes. The obtained results show completely
different dissociation patterns depending on the molecular electronic states studied. These patterns
reflect the bonding properties of the excited orbitals and they permit the description and in some cases
the identification of the different molecular relaxation pathways observed. The achievements
presented in this thesis exemplify the potential of the multicoincidence station used in the reported
experiments.
with synchrotron photons in the 15-35 eV and in the 70-350 eV regions.
In the 15-35 eV region, molecular relaxation by neutral dissociation processes and non
Franck-Condon effects in N2 and O2 molecules have been studied by means of dispersed fluorescence
and photoelectron spectroscopy experimental techniques, respectively. From the dispersed
fluorescence data, excitation functions for the measured atomic fluorescence spectra have been
obtained. From the recorded photoelectron spectra vibrational branching ratios have been produced.
The results obtained reveal that Rydberg series and singly and doubly excited valence states of the
appropriate symmetry energetically accessible in the studied region and interactions between them
account for most of the observed effects in these two type of experiments.
In the 70-350 eV range, molecular relaxation processes resulting in fragmentation of CD4 and
SF6 after absorption of synchrotron light have been studied by energy resolved electron ion
coincidence technique using a multicoincidence experimental station developed by our group during
the last five years for such type of experiments. The coincidence measurements yielded mass spectra
from which information about the kinematics of the detected fragments has been deduced by means of
Monte Carlo simulations of the experimental peak shapes. The obtained results show completely
different dissociation patterns depending on the molecular electronic states studied. These patterns
reflect the bonding properties of the excited orbitals and they permit the description and in some cases
the identification of the different molecular relaxation pathways observed. The achievements
presented in this thesis exemplify the potential of the multicoincidence station used in the reported
experiments.
Publishing year
2002
Language
English
Full text
Document type
Dissertation
Topic
- Electrical Engineering, Electronic Engineering, Information Engineering
Status
Published
Supervisor
- Peter Erman
ISBN/ISSN/Other
- ISRN KTH/FYS/-02:32-SE
- TRITA-FYS-2002:32
Defence date
11 October 2002
Defence time
10:00
Defence place
Stockholm
Opponent
- George King (Professor)