| 1. |
- Marchenko, T., et al.
(author)
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Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime
- 2017
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In: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 119:13
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Journal article (peer-reviewed)abstract
- A combination of resonant inelastic x-ray scattering and resonant Auger spectroscopy provides complementary information on the dynamic response of resonantly excited molecules. This is exemplified for CH3I, for which we reconstruct the potential energy surface of the dissociative I 3d(-2) double-core-hole state and determine its lifetime. The proposed method holds a strong potential for monitoring the hard x-ray induced electron and nuclear dynamic response of core-excited molecules containing heavy elements, where ab initio calculations of potential energy surfaces and lifetimes remain challenging.
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| 2. |
- Squibb, Richard J., et al.
(author)
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Acetylacetone photodynamics at a seeded free-electron laser
- 2018
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- Thefirst steps in photochemical processes, such as photosynthesis or animal vision, involvechanges in electronic and geometric structure on extremely short time scales. Time-resolvedphotoelectron spectroscopy is a natural way to measure such changes, but has been hinderedhitherto by limitations of available pulsed light sources in the vacuum-ultraviolet and soft X-ray spectral region, which have insufficient resolution in time and energy simultaneously. Theunique combination of intensity, energy resolution, and femtosecond pulse duration of theFERMI-seeded free-electron laser can now provide exceptionally detailed information onphotoexcitation–deexcitation and fragmentation in pump-probe experiments on the 50-femtosecond time scale. For the prototypical system acetylacetone we report here electronspectra measured as a function of time delay with enough spectral and time resolution tofollow several photoexcited species through well-characterized individual steps, interpretedusing state-of-the-art static and dynamics calculations. These results open the way forinvestigations of photochemical processes in unprecedented detail.
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| 3. |
- Feifel, Raimund, et al.
(author)
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Cationic double K-hole pre-edge states of CS2 and SF6
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Journal article (peer-reviewed)abstract
- Recent advances in X-ray instrumentation have made it possible to measure the spectra of an essentially unexplored class of electronic states associated with double inner-shell vacancies. Using the technique of single electron spectroscopy, spectra of states in CS2 and SF6 with a double hole in the K-shell and one electron exited to a normally unoccupied orbital have been obtained. The spectra are interpreted with the aid of a high-level theoretical model giving excellent agreement with the experiment. The results shed new light on the important distinction between direct and conjugate shake-up in a molecular context. In particular, systematic similarities and di erences between pre-edge states near single core holes investigated in X-ray absorption spectra and the corresponding states near double core holes studied here are brought out.
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| 4. |
- Goldsztejn, G., et al.
(author)
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Double-Core-Hole States in Neon: Lifetime, Post-Collision Interaction, and Spectral Assignment
- 2016
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 117:13
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Journal article (peer-reviewed)abstract
- Using synchrotron radiation and high-resolution electron spectroscopy, we have directly observed and identified specific photoelectrons from K-2V states in neon corresponding to simultaneous 1s ionization and 1s -> valence excitation. The natural lifetime broadening of the K-2V states and the relative intensities of different types of shakeup channels have been determined experimentally and compared to ab initio calculations. Moreover, the high-energy Auger spectrum resulting from the decay of Ne2+K-2 and Ne+K-2V states as well as from participator Auger decay from Ne+K-1L-1V states, has been measured and assigned in detail utilizing the characteristic differences in lifetime broadenings of these core hole states. Furthermore, post collision interaction broadening of Auger peaks is clearly observed only in the hypersatellite spectrum from K-2 states, due to the energy sharing between the two 1s photoelectrons which favors the emission of one slow and one fast electron.
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| 5. |
- Goldsztejn, G., 2017, et al.
(author)
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Experimental and theoretical study of the double-core-hole hypersatellite Auger spectrum of Ne
- 2017
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In: Physical Review A. - : AMER PHYSICAL SOC. - 2469-9926 .- 2469-9934. ; 96
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Journal article (peer-reviewed)abstract
- We present the hypersatellite Auger spectrum of neon which contains the decay transitions of the K−2, K−2V, K−2L−1, K−2L−1V, and K−1L−1V states. The Auger decays of these types of core-hole states show different line shapes and linewidths which can be distinguished due to the high experimental resolution available for the present experiments. The individual Auger transitions are assigned based on various approaches. Complementary calculations are performed to assign the K−2L−1 → K−1L−3 and the K−2L−1V → K−1L−3V Auger transitions. Based on the obtained results we were able to derive the ratio for the double to single ionization yield.
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| 6. |
- Kushawaha, R. K., et al.
(author)
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Auger resonant-Raman decay after Xe L-edge photoexcitation
- 2015
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 92:1
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Journal article (peer-reviewed)abstract
- We have investigated resonant Auger decay of xenon following photoexcitation of each of the three L edges under resonant-Raman conditions, which allowed us to characterize several higher Rydberg transitions. Relative intensities for spectator final states reached after L-1-, L-2-, and L-3-edge excitations are studied in detail. Thanks to state-of-the-art experimental arrangements, our results not only reproduce the previously calculated 3d(-2)5d and nd (n > 5) state cross sections after L-3 excitation, but also allow extracting the 3d(-2)6d spectator state energy position and revealing its resonant behavior, blurred by the insufficient experimental resolution in previous data sets. The 3d(-2)6p and 3d(-2)7p states reached after L-1 excitation as well as the 3d(-2)5d and 3d(-2)6d states reached after L-2 excitation are also investigated and their relative intensities are reported and compared to ab initio Dirac-Hartree-Fock configuration-interaction calculations. We found the signature of electronic-state-lifetime interference effects between several coherently excited intermediate states, due to large lifetime broadening. Electron recapture processes are also identified above all three photoionization thresholds.
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| 7. |
- Puettner, R., et al.
(author)
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Detailed assignment of normal and resonant Auger spectra of Xe near the L edges
- 2017
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 96:2
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Journal article (peer-reviewed)abstract
- We present a comprehensive experimental and theoretical investigation on the LMM, LMN, and LNN normal Auger spectra of xenon, which reveal excellent agreement with theory when core-hole lifetimes of the two-hole final states are taken into account. Generally, the spectra turned out to be highly complex due to a strong overlap of the Auger transitions subsequent to 2s(1/2)(-1), 2p(1/2)(-1), and 2p(3/2)(-1) ionization. This overlap is due to the splitting of the three initial L core holes and the different final M and N core holes being on the same order of magnitude of several hundred eV. The Auger transitions are assigned in detail based on the theoretical results. Most of the MM, MN, and NN final states are described well based on jj coupling. In addition, we present a detailed assignment of the resonant LM45M45 Auger transition subsequent to the 2s -> 6p, 7p and 2p -> 5d, 6d excitations.
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| 8. |
- Puettner, R., et al.
(author)
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Double core-hole states in SiX4 (X = F, Cl, Br, and CH3) molecules derived by photoelectron and KLL Auger spectroscopy
- 2015
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In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
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Journal article (peer-reviewed)abstract
- In recent years double core-hole states are intensively studied since their chemical shifts provide detailed information about initial-state and relaxation effects in a molecule. We derived the Si 1 s(-1), 2s(-1) and 2p(-1) binding energies as well as the Si 2s(-2), 2(p-1)2p(-1), and 2p(-2) double-core hole binding energies of different SiX4 systems in order to derive the chemical shifts. Based on these results we created Wagner plots, which give insight in the initial state and the relaxation effects in the different molecules.
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| 9. |
- Travnikova, O., et al.
(author)
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Subfemtosecond Control of Molecular Fragmentation by Hard X-Ray Photons
- 2017
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In: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 118:21
-
Journal article (peer-reviewed)abstract
- Tuning hard x-ray excitation energy along Cl 1s -> sigma* resonance in gaseous HCl allows manipulating molecular fragmentation in the course of the induced multistep ultrafast dissociation. The observations are supported by theoretical modeling, which shows a strong interplay between the topology of the potential energy curves, involved in the Auger cascades, and the so-called core-hole clock, which determines the time spent by the system in the very first step. The asymmetric profile of the fragmentation ratios reflects different dynamics of nuclear wave packets dependent on the photon energy.
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| 10. |
- Ueda, Kiyoshi, et al.
(author)
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Roadmap on photonic, electronic and atomic collision physics : I. Light-matter interaction
- 2019
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In: Journal of Physics B. - : IOP PUBLISHING LTD. - 0953-4075 .- 1361-6455. ; 52:17
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Journal article (peer-reviewed)abstract
- We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light-matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field.
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