| 1. |
- Makinen, A., et al.
(författare)
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Relative photoionization cross section of Cr atoms in the valence region
- 2012
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 85:5, s. 053411-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report a measurement of a single photoionization cross section of atomic Cr as a function of photon energy between 10 and 35 eV. The result is compared to a semiempirical model employing orbital-based ionization cross-section calculations from the literature. While the wide energy splitting of the singly ionized valence states explains the behavior of the ionization cross section in the lower-energy end, reasons for the mismatch between the calculations and the experiment in the higher-energy end are discussed.
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| 2. |
- Niskanen, Johannes, et al.
(författare)
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Experimental and theoretical study of core-valence double photoionization of OCS
- 2010
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 82:4, s. 043436-
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Tidskriftsartikel (refereegranskat)abstract
- O 1s, C 1s, and S 2p core-valence double ionization electron spectra of the OCS molecule have been obtained experimentally by a time-of-flight photoelectron-photoelectron coincidence spectroscopy technique. In order to analyze and assign the spectral features observed, we present a protocol for computing core-valence ionization energies of such systems. The protocol is based on a restricted active space multiconfigurational self-consistent field (MCSCF) methodology with a freeze-relax procedure to guarantee a correct core-valence state root index without variational collapse. Corrections for extended dynamical correlation and core-core correlation, respectively, are made by multiconfigurational perturbation theory and by uncontracted basis set Moller-Plesset theory. Envisioning applications to larger molecules, a spin-restricted open-shell density functional method is also applied for the lowest core-valence energies. Furthermore, cross sections through a scheme for computing multiatom Auger transitions generating core-valence holes are presented. We find that the procedure outlined is capable of deriving the energy onset of core-valence ionization within a fraction of an eV and that assignments can be made of the most salient spectral features.
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| 3. |
- Niskanen, Johannes, et al.
(författare)
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Photoelectron angular distribution and linear magnetic dichroism in the 4p photoemission from Rb atoms
- 2010
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 81:1, s. 013406-
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Tidskriftsartikel (refereegranskat)abstract
- The angular distribution of photoelectrons and linear magnetic dichroism in the angular distribution for the 4p photoemission from Rb atoms in the ground state, oriented by laser pumping, were measured in the photon energy range from 50 to 100 eV. The experimental results are compared with the multiconfiguration Dirac-Fock (MCDF) calculations. We show that the zero-crossing of the dichroism as a function of energy is connected with the Cooper minimum in the cross section. This fact can be used for an accurate determination of the position of the Cooper minimum.
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| 4. |
- Niskanen, Johannes, et al.
(författare)
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Valence photoionization of the LiCl monomer and dimer
- 2010
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 81:4, s. 043401-
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a study of valence photoionization of the LiCl monomer and dimer. The behavior of the photoionization partial cross section for molecular valence orbitals was measured as a function of photon energy between 15 and 35 eV. A square-integrable-function method was used to model the ionization partial cross section in both the LiCl monomer and dimer.
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| 5. |
- Schulz, J., et al.
(författare)
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5p photoemission from laser excited cesium atoms
- 2006
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 73:6
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Tidskriftsartikel (refereegranskat)abstract
- Fine-structure resolved 5p photoemission spectra of Cs in the ground state and after laser excitation into the [Xe]6p P-2(1/2) and 6p(2)P(3/2) states have been studied. The 5p(5)6p final states have been reached by the 5p(6)6s -> 5p(5)6p conjugate shakeup process from ground-state atoms as well as by direct photoemission from laser-excited atoms. The laser-excited spectra can be well described with calculations based on the jK-coupling model. Calculations based on a multiconfiguration Dirac-Fock approach have been performed to investigate the deviations created by intermediate coupling from the pure jK-coupling scheme.
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| 6. |
- Schulz, Joachim, et al.
(författare)
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Characterization of weakly excited final states by shakedown spectroscopy of laser-excited potassium
- 2006
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 74:1, s. 012705-
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Tidskriftsartikel (refereegranskat)abstract
- 3p shakedown spectra of laser excited potassium atoms as well as direct 3p photoemission of ground state potassium have been studied. These two excitation schemes lead to the same final states and thereby provide a good basis for a detailed study of the 3p(5)(4s3d)(1) configurations of singly ionized potassium and the photoemission processes leading to these configurations. The comparison of direct photoemission from the ground state and conjugate shakedown spectra from 4p(1/2) laser excited potassium made it possible to experimentally determine the character of final states that are only weakly excited in the direct photoemission but have a much higher relative intensity in the shakedown spectrum. Based on considerations of angular momentum and parity conservation the excitation scheme of the final states can be understood.
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| 7. |
- Urpelainen, S., et al.
(författare)
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Valence photoionization and the following fragmentation pathways in Sb-4 clusters
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 80:4, s. 043201-
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Tidskriftsartikel (refereegranskat)abstract
- The valence photoelectron spectrum of Sb-4 clusters and the following fragmentation patterns have been studied using synchrotron radiation and electron-ion coincidence technique. An experimental photoelectron spectrum of the 5t(2) ionization of Sb-4 is presented. Theoretical molecular calculations, together with the existing data on the noble gas xenon, were used to describe the experimental results. The bonding properties of the molecular orbitals involved are used to qualitatively describe the dissociation process.
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| 8. |
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| 9. |
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| 10. |
- AUSMEES, A, et al.
(författare)
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OBSERVATION OF ANOMALOUS BEHAVIOR OF THE XE 4D PHOTOELECTRON SATELLITES
- 1995
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Ingår i: PHYSICAL REVIEW A. - : AMER INST PHYSICS. - 1050-2947. ; 52:4, s. 2943-2947
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Xe 4d photoelectron satellites have been studied in the photon energy region 90-200 eV. The substantially improved energy resolution has enabled us to determine a wealth of satellites. A comparison of the satellite spectra at the intermediate excitati
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