Inner-shell photoionization and core-hole decay of Xe and XeF$_2$
| Autor: | Stephen H. Southworth, Ralf Wehlitz, Lan Cheng, Antonio Picón, C. Stefan Lehmann, John F. Stanton |
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| Rok vydání: | 2015 |
| Předmět: |
Physics
Atomic Physics (physics.atom-ph) Polyatomic ion General Physics and Astronomy Resonance FOS: Physical sciences Photoionization Electron 7. Clean energy Ion Physics - Atomic Physics Delocalized electron Ionization Physics::Atomic and Molecular Clusters Physics - Atomic and Molecular Clusters Physical and Theoretical Chemistry Atomic physics Atomic and Molecular Clusters (physics.atm-clus) HOMO/LUMO |
| DOI: | 10.48550/arxiv.1507.01493 |
| Popis: | Photoionization cross sections and partial ion yields of Xe and XeF$_2$ from Xe 3d$_{5/2}$, Xe 3d$_{3/2}$, and F 1s subshells in the 660--740 eV range are compared to explore effects of the F ligands. The Xe 3d - $\epsilon$f continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF$_2$ cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. The subshell ionization thresholds, the LUMO resonance energies and their oscillator strengths are calculated by relativistic coupled-cluster methods. Several charge states and fragment ions are produced from the atom and molecule due to alternative decay pathways from the inner-shell holes. Total and partial ion yields vary in response to the shape resonances and LUMO resonances. Previous calculations and measurements of atomic Xe 3d core-hole decay channels and our calculated results for XeF$_2$ guide interpretations of the molecular ion products. The partial ion yields of XeF$_2$ are dominated by Xe 3d core-hole decays, but distinct ion products are measured at the F 1s - LUMO resonance. Xe 3d core-hole decays from XeF$_2$ produce lower charge states in comparison with atomic Xe, and energetic F ions are produced by Coulomb explosions of the molecular ions. The measurements support a model of molecular core-hole decay that begins with a localized hole, stepwise Auger electron emission spreads charge across neighboring atoms, and the system fragments energetically. |
| Databáze: | OpenAIRE |
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