uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Radiative and Relativistic Effects in the Decay of Highly Excited States in Helium
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
Show others and affiliations
2000 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 85, no 6, 1202-1205 p.Article in journal (Refereed) Published
Abstract [en]

A recent experimental study [J.-E. Rubensson et al., Phys. Rev. Lett. 83, 947 (1999)] measured a significant fluorescence yield of the He( 2lnl) photoexcited resonances, showing major qualitative differences from nonrelativistic predictions. We present a further theoretical study of these states, and perform R-matrix multichannel quantum defect theory calculations to extract fluorescence and ionization cross sections. These theoretical results are in excellent agreement with newer, higher-resolution measurements. Radiative and spin-orbit effects are quantified and shown to play an important role in the overall characterization of highly excited states.

Place, publisher, year, edition, pages
2000. Vol. 85, no 6, 1202-1205 p.
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-94516DOI: 10.1103/PhysRevLett.85.1202OAI: oai:DiVA.org:uu-94516DiVA: diva2:168389
Available from: 2006-05-05 Created: 2006-05-05 Last updated: 2016-04-26Bibliographically approved
In thesis
1. Double Excitations in Helium Atoms and Lithium Compounds
Open this publication in new window or tab >>Double Excitations in Helium Atoms and Lithium Compounds
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis addresses the investigation of doubly excited 2l´nl states in helium atoms and double core excitations in solid lithium compounds.

Measurements on He are made in field free environments and under the influence of electric and magnetic fields, using synchrotron based inelastic photon scattering. Cross sections for scattering to singly excited final states are directly determined and compared to theoretical results and are found to be in excellent agreement. Radiative and spin-orbit effects are quantified and are shown to play an important role in the overall characterization of highly excited He states below the N =2 threshold. A dramatic electric field dependence is also observed in the flourecence yield already for relatively weak fields. This signal increase, induced by electric as well as magnetic fields, is interpreted in terms of mixing with states of higher fluorescence branching ratios.

Double core excitations at the lithium site in solid lithium compounds are investigated using resonant inelastic x-ray scattering (RIXS). The lithium halides LiF, LiCl, LiBr and LiI are studied as well as the molecular compounds Li2O, Li2CO3 and LiBF4. States with one, as well as both, of the excited electrons localized at the site of the bare lithium nucleus are identified, and transitions which involve additional band excitations are observed. A strong influence of the chemical surrounding is found, and it is discussed in terms of the ionic character of the chemical bond.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 114 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 186
Keyword
Atomic and molecular physics, Soft X-ray emission, resonant inelastic X-ray scattering, double excitations, lithium halide, helium, Atom- och molekylfysik
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-6889 (URN)91-554-6572-2 (ISBN)
Public defence
2006-05-26, Polhelmsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15
Opponent
Supervisors
Available from: 2006-05-05 Created: 2006-05-05 Last updated: 2016-04-21Bibliographically approved
2. Applications of Soft X-Ray Spectroscopy
Open this publication in new window or tab >>Applications of Soft X-Ray Spectroscopy
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Soft X-ray emission spectroscopy is an old experimental technique that has seen a strong revival since the advent of new high brilliance soft X-ray sources in the shape of synchrotrons.  This thesis covers a range of applications where soft x-ray techniques have been applied. I have looked at fluorescence yield from doubly excited helium in field free conditions as well as in the presence of weak electric and magnetic fields. Using soft X-ray emission spectroscopy (SXES) I have explored scattering mechanisms in molecular systems. Quenching of symmetry breaking transitions by detuning of the excitation energy was observed in CO2. Bond-length dependence was seen for symmetry breaking transitions in a series of hydrocarbons. Dissociation dynamics was explored in OCS and HCl. I have also applied SXES to liquid water exploring the properties of hydrogen bonding.  Buried layers of AlAs under 100 Å GaAs(100) was studied and thickness dependence and interface effects observed. The technique was also used to study the electronic structure of yttrium and vanadium hydrides. dd-excitations and accompanying spin flip excitations was observed in Cu M resonant x-ray Raman emission from Sr2CuO2Cl2.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 61 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 860
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-159369 (URN)978-91-554-8173-5 (ISBN)
Public defence
2011-11-11, Å4001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2011-10-21 Created: 2011-09-29 Last updated: 2011-11-04Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Agåker, Marcus

Search in DiVA

By author/editor
Agåker, Marcus
By organisation
Department of PhysicsPhysics II
In the same journal
Physical Review Letters
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 598 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf