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Neutral dissociation and non Franck-Condon effects in valence excited N and O molecules

Rius i Riu, Jaume LU (2001)
Abstract
Neutral photodissociation processes and non Franck-Condon effects in the N2 and O2 molecules

induced by excitation with synchrotron radiation photons have been studied in the 15-35 eV region.

Neutral dissociation processes have been studied by monitoring dispersed fluorescence from

excited N and O atoms. The excited atoms are created through excitations to members of the molecular

Rydberg series, which predissociate yielding excited atomic fragments. From comparison with

calculations performed using many-body perturbation theory it follows that predissociations of N2

Rydberg series are caused by a number of non-Rydberg doubly excited resonances whereas

predissociation of... (More)
Neutral photodissociation processes and non Franck-Condon effects in the N2 and O2 molecules

induced by excitation with synchrotron radiation photons have been studied in the 15-35 eV region.

Neutral dissociation processes have been studied by monitoring dispersed fluorescence from

excited N and O atoms. The excited atoms are created through excitations to members of the molecular

Rydberg series, which predissociate yielding excited atomic fragments. From comparison with

calculations performed using many-body perturbation theory it follows that predissociations of N2

Rydberg series are caused by a number of non-Rydberg doubly excited resonances whereas

predissociation of O2 Rydberg series occur after interaction with close-lying singly and doubly excited

valence states of the appropriate symmetry.

Photoelectron spectroscopy has been used to study photoionization of the N2 molecules to the

N2+ A 2Πu state and photoionization of the O2 molecules to the O2+ X 2Πg state. Dispersed fluorescence

emitted from the O2+ molecules has been measured to study the photoionization to the b 4Σ-g state of

O2+. All three photoionization channels exhibit strong non Franck-Condon effects in their experimental

vibrational branching ratios. In the case of the b 4Σ-g state of O2+, these effects seems to be originated

by the narrow 3σg σu shape resonance coupled to the 1πu πg channel. Conversely, the σu shape

resonance does not control the ionization to the O2+ X 2Πg and to the N2+ A 2Πu states. Photoionization

of the O2 πg electron is not fully explained by autoionization from known Rydberg series and valence

states, which suggest the existence of unknown process affecting this photoionization channel. On the

contrary, the Franck-Condon breakdown in the ionization to the N2+ A 2Πu state in the studied region is

attributed to autoionization from Rydberg and valence states of N2. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Thesis
publication status
published
subject
pages
45 pages
publisher
Stockholm: KTH, Physics
external identifiers
  • other:Trita-FYS, ISSN 0280-316X ; 1073
language
English
LU publication?
no
id
196f9a9c-c274-418c-ab1c-da4e64a7de32 (old id 1029802)
date added to LUP
2008-02-18 11:56:17
date last changed
2016-09-19 08:45:13
@misc{196f9a9c-c274-418c-ab1c-da4e64a7de32,
  abstract     = {Neutral photodissociation processes and non Franck-Condon effects in the N2 and O2 molecules <br/><br>
induced by excitation with synchrotron radiation photons have been studied in the 15-35 eV region. <br/><br>
Neutral dissociation processes have been studied by monitoring dispersed fluorescence from <br/><br>
excited N and O atoms. The excited atoms are created through excitations to members of the molecular <br/><br>
Rydberg series, which predissociate yielding excited atomic fragments. From comparison with <br/><br>
calculations performed using many-body perturbation theory it follows that predissociations of N2 <br/><br>
Rydberg series are caused by a number of non-Rydberg doubly excited resonances whereas <br/><br>
predissociation of O2 Rydberg series occur after interaction with close-lying singly and doubly excited <br/><br>
valence states of the appropriate symmetry. <br/><br>
Photoelectron spectroscopy has been used to study photoionization of the N2 molecules to the <br/><br>
N2+ A 2Πu state and photoionization of the O2 molecules to the O2+ X 2Πg state. Dispersed fluorescence <br/><br>
emitted from the O2+ molecules has been measured to study the photoionization to the b 4Σ-g state of <br/><br>
O2+. All three photoionization channels exhibit strong non Franck-Condon effects in their experimental <br/><br>
vibrational branching ratios. In the case of the b 4Σ-g state of O2+, these effects seems to be originated <br/><br>
by the narrow 3σg σu shape resonance coupled to the 1πu πg channel. Conversely, the σu shape <br/><br>
resonance does not control the ionization to the O2+ X 2Πg and to the N2+ A 2Πu states. Photoionization <br/><br>
of the O2 πg electron is not fully explained by autoionization from known Rydberg series and valence <br/><br>
states, which suggest the existence of unknown process affecting this photoionization channel. On the <br/><br>
contrary, the Franck-Condon breakdown in the ionization to the N2+ A 2Πu state in the studied region is <br/><br>
attributed to autoionization from Rydberg and valence states of N2.},
  author       = {Rius i Riu, Jaume},
  language     = {eng},
  note         = {Licentiate Thesis},
  pages        = {45},
  publisher    = {Stockholm: KTH, Physics},
  title        = {Neutral dissociation and non Franck-Condon effects in valence excited N and O molecules},
  year         = {2001},
}