| 1. |
- Kukk, E., et al.
(författare)
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Formative period in the x-ray-induced photodissociation of organic molecules
- 2021
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Ingår i: Physical Review Research. - 2643-1564. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Absorption of x-ray photons by atomic inner shells of light-element organics and biomolecules often leads to formation of dicationic electronic states and to molecular fragmentation. We investigated the x-ray-induced dissociation landscape of a representative medium-sized organic molecule, thiophene, by femtosecond x-ray pulses from the Super Photon Ring-8 GeV (SPring-8) Angstrom Compact Free-Electron Laser (SACLA). Holes, created in the sulfur 2p orbital by photoemission, were filled by the Auger process that created dicationic molecular states within a broad range of internal energies—a starting point particular to x-ray-induced dynamics. The evolution of the ionized molecules was monitored by a pump-probe experiment using a near-infrared (800 nm) laser pulse. Ion-ion coincidence and ion momentum analysis reveals enhanced yields of ionic fragments from multibody breakup of the ring, attributed to additional ionization of the highly excited fraction of the dicationic parent molecular states. The transient nature of the enhancement and its decay with about a 160-fs time constant indicate formation of an open-ring parent geometry and the statistical survival time of the parent species before the dissociation events. By probing specific Auger final states of transient, highly excited nature by near-infrared light, we demonstrate how pump-probe signatures can be related to the key features in dynamics during the early period of the x-ray-induced damage of organic molecules and biomolecules.
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| 2. |
- Fukuzawa, H., et al.
(författare)
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Deep Inner-Shell Multiphoton Ionization by Intense X-Ray Free-Electron Laser Pulses
- 2013
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 110:17
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated multiphoton multiple ionization dynamics of xenon atoms using a new x-ray free-electron laser facility, SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan, and identified that Xen+ with n up to 26 is produced at a photon energy of 5.5 keV. The observed high charge states (n >= 24) are produced via five-photon absorption, evidencing the occurrence of multiphoton absorption involving deep inner shells. A newly developed theoretical model, which shows good agreement with the experiment, elucidates the complex pathways of sequential electronic decay cascades accessible in heavy atoms. The present study of heavy-atom ionization dynamics in high-intensity hard-x-ray pulses makes a step forward towards molecular structure determination with x-ray free-electron lasers. DOI: 10.1103/PhysRevLett.110.173005
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| 3. |
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| 4. |
- Iablonskyi, D., et al.
(författare)
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Interatomic Coulombic Decay Processes after Multiple Valence Excitations in Ne Clusters
- 2015
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 635, s. 112067-112067
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Konferensbidrag (refereegranskat)abstract
- We present a comprehensive analysis of autoionization processes in Ne clusters (similar to 5000 atoms) after multiple valence excitations by free electron laser radiation. The evolution from 2-body interatomic Coulombic decay (ICD) to 3-body ICD is demonstrated when changing from surface to bulk Frenkel exciton excitation. Super Coster-Kronig type 2-body ICD is observed at Wannier exciton which quenches the main ICD channel.
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| 5. |
- Iablonskyi, D., et al.
(författare)
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Slow Interatomic Coulombic Decay of Multiply Excited Neon Clusters
- 2016
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Ingår i: Physical Review Letters. - 0031-9007. ; 117:27
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Tidskriftsartikel (refereegranskat)abstract
- Ne clusters (∼5000 atoms) were resonantly excited (2p→3s) by intense free electron laser (FEL) radiation at FERMI. Such multiply excited clusters can decay nonradiatively via energy exchange between at least two neighboring excited atoms. Benefiting from the precise tunability and narrow bandwidth of seeded FEL radiation, specific sites of the Ne clusters were probed. We found that the relaxation of cluster surface atoms proceeds via a sequence of interatomic or intermolecular Coulombic decay (ICD) processes while ICD of bulk atoms is additionally affected by the surrounding excited medium via inelastic electron scattering. For both cases, cluster excitations relax to atomic states prior to ICD, showing that this kind of ICD is rather slow (picosecond range). Controlling the average number of excitations per cluster via the FEL intensity allows a coarse tuning of the ICD rate.
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| 6. |
- Motomura, K., et al.
(författare)
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Sequential multiphoton multiple ionization of atomic argon and xenon irradiated by X-ray free-electron laser pulses from SACLA
- 2013
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 46:16
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated multiphoton multiple ionization of argon and xenon atoms at 5 keV using a new x-ray free electron laser (XFEL) facility, the SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan. The experimental results are compared with the new theoretical results presented here. The absolute fluence of the XFEL pulse has been determined with the help of the calculations utilizing two-photon processes in the argon atom. The high charge states up to +22 observed for Xe in comparison with the calculations point to the occurrence of sequential L-shell multiphoton absorption and of resonance-enabled x-ray multiple ionization.
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| 7. |
- Rouzee, A., et al.
(författare)
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Angle-resolved photoelectron spectroscopy of sequential three-photon triple ionization of neon at 90.5 eV photon energy
- 2011
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 83:3
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Tidskriftsartikel (refereegranskat)abstract
- Multiple photoionization of neon atoms by a strong 13.7 nm (90.5 eV) laser pulse has been studied at the FLASH free electron laser in Hamburg. A velocity map imaging spectrometer was used to record angle-resolved photoelectron spectra on a single-shot basis. Analysis of the evolution of the spectra with the FEL pulse energy in combination with extensive theoretical calculations allows the ionization pathways that contribute to be assigned, revealing the occurrence of sequential three-photon triple ionization.
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| 8. |
- Takanashi, T, et al.
(författare)
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Time-Resolved Measurement of Interatomic Coulombic Decay Induced by Two-Photon Double Excitation of Ne2
- 2017
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Ingår i: Physical Review Letters. - 0031-9007. ; 118:3
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Tidskriftsartikel (refereegranskat)abstract
- The hitherto unexplored two-photon doubly excited states [Ne∗(2p-13s)]2 were experimentally identified using the seeded, fully coherent, intense extreme ultraviolet free-electron laser FERMI. These states undergo ultrafast interatomic Coulombic decay (ICD), which predominantly produces singly ionized dimers. In order to obtain the rate of ICD, the resulting yield of Ne2+ ions was recorded as a function of delay between the extreme ultraviolet pump and UV probe laser pulses. The extracted lifetimes of the long-lived doubly excited states, 390(-130/+450) fs, and of the short-lived ones, less than 150 fs, are in good agreement with ab initio quantum mechanical calculations.
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| 9. |
- Fukuzawa, H., et al.
(författare)
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Electron spectroscopy of rare-gas clusters irradiated by x-ray free-electron laser pulses from SACLA
- 2016
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Ingår i: Journal of Physics B-Atomic Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 49:3
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Tidskriftsartikel (refereegranskat)abstract
- We have measured electron energy spectra and asymmetry parameters of Ar clusters and Xe clusters illuminated by intense x-rays at 5 and 5.5 keV. A velocity map imaging spectrometer was developed for this purpose and employed at an x-ray free-electron laser facility, SACLA in Japan. The cluster size dependence and the peak fluence dependence of the electron spectra and asymmetry parameters are discussed.
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| 10. |
- Gryzlova, E. V., et al.
(författare)
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Doubly resonant three-photon double ionization of Ar atoms induced by an EUV free-electron laser
- 2011
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 84:6
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Tidskriftsartikel (refereegranskat)abstract
- A mechanism for three-photon double ionization of atoms by extreme-ultraviolet free-electron laser pulses is revealed, where in a sequential process the second ionization step, proceeding via resonant two-photon ionization of ions, is strongly enhanced by the excitation of ionic autoionizing states. In contrast to the conventional model, the mechanism explains the observed relative intensities of photoelectron peaks and their angular dependence in three-photon double ionization of argon.
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