| 1. |
- Miteva, Tsveta, et al.
(författare)
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The All-Seeing Eye of Resonant Auger Electron Spectroscopy : A Study on Aqueous Solution Using Tender X-rays
- 2018
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 9:15, s. 4457-4462
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption and Auger electron spectroscopies are demonstrated to be powerful tools to unravel the electronic structure of solvated ions. In this work for the first time, we use a combination of these methods in the tender X-ray regime. This allowed us to address electronic transitions from deep core levels, to probe environmental effects, specifically in the bulk of the solution since the created energetic Auger electrons possess large mean free paths, and moreover, to obtain dynamical information about the ultrafast delocalization of the core-excited electron. In the considered exemplary aqueous KCl solution, the solvated isoelectronic K+ and Cl- ions exhibit notably different Auger electron spectra as a function of the photon energy. Differences appear due to dipole-forbidden transitions in aqueous K+ whose occurrence, according to the performed ab initio calculations, becomes possible only in the presence of solvent water molecules.
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| 2. |
- Agueny, Hicham, et al.
(författare)
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Electron capture, ionization and excitation cross sections for keV collisions between fully stripped ions and atomic hydrogen in ground and excited states
- 2019
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier BV. - 1090-2090 .- 0092-640X. ; 129-130:September–November 2019
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Tidskriftsartikel (refereegranskat)abstract
- Using a semiclassical close-coupling approach, we have calculated electron capture, excitation and ionization cross sections for collisions of fully stripped hydrogen, helium and lithium ions with atomic hydrogen in the ground state and in all excited states up to n=3. The cross sections for collision energies between 1 and 100 keV/u are given in table form. Furthermore, we provide estimates of the accuracy of the cross sections. The set of data presented in this work represent the first complete and consistent quantum study of these collision systems and will find use in the modeling and diagnosis of thermonuclear fusion plasma reactors.
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| 3. |
- Capron, Nathalie, et al.
(författare)
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Correction: Probing keto–enol tautomerism using photoelectron spectroscopy
- 2018
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 20:1, s. 695-695
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Tidskriftsartikel (refereegranskat)abstract
- Correction for ‘Probing keto–enol tautomerism using photoelectron spectroscopy’ by Nathalie Capron et al., Phys. Chem. Chem. Phys., 2015, 17, 19991–19996.
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| 4. |
- Capron, Nathalie, et al.
(författare)
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Probing keto-enol tautomerism using photoelectron spectroscopy
- 2015
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 17:30, s. 19991-19996
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically investigate the mechanism of tautomerism in the gas-phase acetylacetone molecule. The minimum energy path between the enolone and diketo forms has been computed using the Nudged-Elastic Band (NEB) method within the density-functional theory (DFT) using the projector augmented-wave method and generalized gradient approximation in Perdew-Wang (PW91) parametrization. The lowest transition state as well as several intermediate geometries between the two stable tautomers have been identified. The outer-valence ionization spectra for all determined geometries have been computed using the third-order non-Dyson algebraic diagrammatic construction technique. Furthermore, the oxygen core-shell ionization spectra for these geometries have been obtained using DFT and the Becke three-parameter Lee-Yang-Parr (B3LYP) functional. It is shown that all spectra depend strongly on the geometries demonstrating the possibility of following the proton-transfer dynamics using photoelectron spectroscopy in pump-probe experiments.
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| 5. |
- Hörnquist, Johan, 1990-
(författare)
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A unified model of reactive scattering processes : Application to the H2 reaction complex
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, reactive scattering processes involving the H2 reaction complex are studied ab initio and fully quantum mechanically. These processes have in common that they involve highly excited electronic states, which could be either bound or resonant. Non-adiabatic couplings, which can be significant both at small and large internuclear distances, need to be included to account for the interaction between the bound electronic states. In addition, the electronic resonant states interact with the ionization continuum at small internuclear distances, which may cause the collision complex to autoionize. In this work, a model is developed which incorporates these different coupling mechanisms. By introducing a quasidiabatic model at small internuclear distances, resonant states and couplings to the ionization continuum are incorporated. The quasidiabatic model is combined with a strict diabatic description, which rigorously incorporates non-adiabatic couplings among the bound electronic states. Nuclear dynamics are solved for using a close-coupling approach in a strict diabatic representation, where a non-local complex potential is included to account for loss into the ionization continuum. With this model, various reactive scattering processes can systematically be studied using the same set of potential energy curves and couplings. The model is applied in studies of H++H- mutual neutralization, H(1s)+H(ns) and H++H- associative ionization as well as dissociative recombination and resonant ion-pair formation in electron collisions with HD+. Cross sections and branching ratios are compared with results from previous experiments and theoretical studies.
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| 6. |
- Poline, Mathias, et al.
(författare)
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Final-state-resolved mutual neutralization in I+ - I− collisions
- 2022
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 106:1
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the mutual neutralization reaction of atomic iodine ions (i.e., I++I−→I+I) in a cryogenic double electrostatic ion-beam storage-ring apparatus. Our results show that the reaction forms iodine atoms either in the ground-state configuration (I(5p52P∘), ∼40%) or with one atom in an electronically excited state (I(6s2[2]), ∼60%), with no significant variation over the branching ratios in the studied collision-energy range (0.1–0.8 eV). We estimate the total charge-transfer cross section to be of the order of 10−13cm2 at 0.1 eV collision energy. Ab initio relativistic electronic structure calculations of the potential-energy curves of I2 suggest that the reaction takes place at short internuclear distances. The results are discussed in view of their importance for applications in electric thrusters.
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| 7. |
- Richter, Clemens, et al.
(författare)
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Competition between proton transfer and intermolecular Coulombic decay in water
- 2018
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Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Intermolecular Coulombic decay (ICD) is a ubiquitous relaxation channel of electronically excited states in weakly bound systems, ranging from dimers to liquids. As it is driven by electron correlation, it was assumed that it will dominate over more established energy loss mechanisms, for example fluorescence. Here, we use electron-electron coincidence spectroscopy to determine the efficiency of the ICD process after 2a(1) ionization in water clusters. We show that this efficiency is surprisingly low for small water clusters and that it gradually increases to 40-50% for clusters with hundreds of water units. Ab initio molecular dynamics simulations reveal that proton transfer between neighboring water molecules proceeds on the same timescale as ICD and leads to a configuration in which the ICD channel is closed. This conclusion is further supported by experimental results from deuterated water. Combining experiment and theory, we infer an intrinsic ICD lifetime of 12-52 fs for small water clusters.
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| 8. |
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| 9. |
- Travnikova, Oksana, et al.
(författare)
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Hard-X-Ray-Induced Multistep Ultrafast Dissociation
- 2016
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116:21
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Tidskriftsartikel (refereegranskat)abstract
- Creation of deep core holes with very short (tau <= 1 fs) lifetimes triggers a chain of relaxation events leading to extensive nuclear dynamics on a few-femtosecond time scale. Here we demonstrate a general multistep ultrafast dissociation on an example of HCl following Cl 1s -> sigma* excitation. Intermediate states with one or multiple holes in the shallower core electron shells are generated in the course of the decay cascades. The repulsive character and large gradients of the potential energy surfaces of these intermediates enable ultrafast fragmentation after the absorption of a hard x-ray photon.
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