| 1. |
- Kivimäki, Antti, et al.
(författare)
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An energy resolved electron-ion coincidence study near the S 2p thresholds of the SF6 molecule
- 2003
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 36:4, s. 781-791
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Tidskriftsartikel (refereegranskat)abstract
- The fragmentation dynamics of the SF6 molecule following the excitations of S 2p electrons into unoccupied molecular orbitals has been studied using the energy-resolved electron-ion coincidence technique. Fragmentation patterns were found to depend on the particular excitation and on the electronic state of the molecular ion. The spectator resonant Auger decay at the 2p --> 6a(1g) resonance induces changes in the ion distributions as compared to direct photoionization. Furthermore, coincidence spectra related to the same Auger structure display different ion abundances at the 2t(2g) and 4e(g) shape resonances. Differences were also found in the Auger decay spectra. These findings give further support for the previously suggested many-electron character of the 4e(g) shape resonance.
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| 2. |
- Rius i Riu, Jaume, 1973-
(författare)
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Gas phase molecular relaxation probed by synchrotron radiation experiments
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents experimental studies of gas phasemolecular relaxation after excitation with synchrotron photonsin the 15-35 eV and in the 70-350 eV regions.In the 15-35 eV region, molecular relaxation by neutraldissociation processes and nonFranck-Condon effects in N2 and O2 molecules have beenstudied by means of dispersed fluorescence and photoelectronspectroscopy experimental techniques, respectively. From thedispersed fluorescence data, excitation functions for themeasured atomic fluorescence spectra have been obtained. Fromthe recorded photoelectron spectra vibrational branching ratioshave been produced. The results obtained reveal that Rydbergseries and singly and doubly excited valence states of theappropriate symmetry energetically accessible in the studiedregion and interactions between themaccount for most of theobserved effects in these two type of experiments.In the 70-350 eV range, molecular relaxation processesresulting in fragmentation of CD4 and SF6 after absorption ofsynchrotron light have been studied by energy resolved electronion coincidence technique using a multicoincidence experimentalstation developed by our group during the last five years forsuch type of experiments. The coincidence measurements yieldedmass spectra from which information about the kinematics of thedetected fragments has been deduced by means of Monte Carlosimulations of the experimental peak shapes. The obtainedresults show completely different dissociation patternsdepending on the molecular electronic states studied. Thesepatterns reflect the bonding properties of the excited orbitalsand they permit the description and in some cases theidentification of the different molecular relaxation pathwaysobserved. The achievements presented in this thesis exemplifythe potential of the multicoincidence station used in thereported experiments.
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| 3. |
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| 4. |
- Stankiewicz, Marek, et al.
(författare)
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Experimental station for gas phase fluorescence spectroscopy
- 2004
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 75:7, s. 2402-2408
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Tidskriftsartikel (refereegranskat)abstract
- The details of an experimental setup for gas phase atomic and molecular fluorescence measurements using synchrotron radiation are described in this article. The most significant part of the apparatus is an optical arrangement, which allows for simultaneous measurements of dispersed as well as total fluorescence intensity using an effusive gas jet and an inbuilt gas cell assembled in a convenient plug and measure configuration. The first measurements concerning fluorescence of the N-2 molecule around the N 1s edge obtained with this setup are presented.
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| 5. |
- Stankiewicz, M., et al.
(författare)
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Relaxation dynamics of SF6 studied by energy-resolved electron ion coincidence technique
- 2004
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 137-40, s. 369-375
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Tidskriftsartikel (refereegranskat)abstract
- The mass spectra from the SF6 molecule acquired by energy-resolved electron ion coincidence (EREICO) technique using (1t(1g) + [5t(1u),1t(2u)]), (3e(g) + 1t(2g)), 4t(1u), and 5a(1g) electrons after both valence and S 2p(-1) 6a(1g) core excitation reveal a strong selectivity in the dissociation from these states. From the comparison of the obtained spectra, the influence of the core-excited state in the relaxation pathway of the molecule is studied. The S 2p --> 6a(1g) core excitation does not affect the relaxation dynamics after participator Auger decay to the (1t(1g) + [5t(1u),1t(2u)])(-1) and (4t(1u))(-l) states, but it alters the relaxation dynamics after participator Auger decay to the (3e(g) + 1t(2g))(-1) and (5a(1g))(-1) states with respect to the decay processes after direct excitation of the same orbitals. These observations point to core excitation induced dissociation in the SF6 molecule.
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