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1. Time-resolved study of resonant interatomic Coulombic decay in helium nanodroplets

Author

LaForge, A. C., Michiels, R., Ovcharenko, Y., Ngai, A., Escartin, J. M., Berrah, N., Callegari, C., Clark, A., Coreno, M., Cucini, R., Di Fraia, M., Drabbels, M., Fasshauer, E., Finetti, P., Giannessi, L., Grazioli, C., Iablonskyi, D., Langbehn, B., Nishiyama, T., Oliver, V., Piseri, P., Plekan, O., Prince, K. C., Rupp, D., Stranges, S., Ueda, K., Sisourat, N., Eloranta, J., Pi, M., Barranco, M., Stienkemeier, F., Moeller, T., and Mudrich, M.

Subjects
Physics - Atomic and Molecular Clusters
Abstract

When weakly-bound complexes are multiply excited by intense electromagnetic radiation, energy can be exchanged between neighboring atoms through a type of resonant interatomic Coulombic decay (ICD). This decay mechanism due to multiple excitations has been predicted to be relatively slow, typically lasting tens to hundreds of picoseconds. Here, we directly measure the ICD timescale in resonantly excited helium droplets using a high resolution, tunable, extreme ultraviolet free electron laser. Over an extensive range of droplet sizes and laser intensities, we discover the decay to be surprisingly fast, with decay times as fast as 400 femtoseconds, and to only present a weak dependence on the density of the excited states. Using a combination of time dependent density functional theory and ab initio quantum chemistry calculations, we elucidate the mechanisms of this ultrafast decay process where pairs of excited helium atoms in one droplet strongly attract each other and form merging void bubbles which drastically accelerates ICD.

Published
2020
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2. Time-resolved observation of interatomic Coulombic decay induced by two-photon double excitation of Ne$_{2}$

Author

Takanashi, T., Golubev, N. V., Callegari, C., Fukuzawa, H., Motomura, K., Iablonskyi, D., Kumagai, Y., Mondal, S., Tachibana, T., Nagaya, K., Nishiyama, T., Matsunami, K., Johnsson, P., Piseri, P., Sansone, G., Dubrouil, A., Reduzzi, M., Carpeggiani, P., Vozzi, C., Devetta, M., Negro, M., Faccialà, D., Calegari, F., Trabattoni, A., Castrovilli, M. C., Ovcharenko, Y., Mudrich, M., Stienkemeier, F., Coreno, M., Alagia, M., Schütte, B., Berrah, N., Plekan, O., Finetti, P., Spezzani, C., Ferrari, E., Allaria, E., Penco, G., Serpico, C., De Ninno, G., Diviacco, B., Di Mitri, S., Giannessi, L., Jabbari, G., Prince, K. C., Cederbaum, L. S., Demekhin, Ph. V., Kuleff, A. I., and Ueda, K.

Subjects
Physics - Atomic Physics, Physics - Atomic and Molecular Clusters, Physics - Optics
Abstract

The hitherto unexplored two-photon doubly-excited states [Ne$^{*}$($2p^{-1}3s$)]$_{2}$ 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 Ne$_{2}^{+}$ ions was recorded as a function of delay between the XUV 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 \emph{ab initio} quantum mechanical calculations.

Published
2019

3. Autoionization dynamics of He nanodroplets resonantly excited by intense XUV laser pulses

Author

Ovcharenko, Y., LaForge, A., Langbehn, B., Plekan, O., Cucini, R., Finetti, P., O'Keeffe, P., Iablonskyi, D., Nishiyama, T., Ueda, K., Piseri, P., DiFraia, M., Richter, R., Coreno, M., Callegari, C., Prince, K. C., Stienkemeier, F., Moller, T., and Mudrich, M.

Subjects
Physics - Atomic and Molecular Clusters, 14J60 (Primary) 14F05, 14J26 (Secondary)
Abstract

The ionization dynamics of helium droplets in a wide size range from 220 to 10^6 He atoms irradiated with intense femtosecond extreme ultraviolet (XUV) pulses of 10^9 {\div} 10^{12} W/cm2 power density is investigated in detail by photoelectron spectroscopy. Helium droplets are resonantly excited in the photon energy range from ~ 21 eV (corresponding to the atomic 1s2s state) up to the atomic ionization potential (IP) at ~ 25 eV. A complex evolution of the electron spectra as a function of droplet size and XUV intensity is observed, ranging from atomic-like narrow peaks due to binary autoionization, to an unstructured feature characteristic of electron emission from a nanoplasma. The experimental results are analyzed and interpreted with the help of numerical simulations based on rate equations taking into account various processes such as multi-step ionization, interatomic Coulombic decay (ICD), secondary inelastic collisions, desorption of electronically excited atoms, collective autoionization (CAI) and further relaxation processes., Comment: 20 pages, 14 figures, 43 references

Published
2019

4. Observation and Control of Laser-Enabled Auger Decay

Author

Iablonskyi, D., Ueda, K., Ishikawa, Kenichi L., Kheifets, A. S., Carpeggiani, P., Reduzzi, M., Ahmadi, H., Comby, A., Sansone, G., Csizmadia, T., Kuehn, S., Ovcharenko, E., Mazza, T., Meyer, M., Fischer, A., Callegari, C., Plekan, O., Finetti, P., Allaria, E., Ferrari, E., Roussel, E., Gauthier, D., Giannessi, L., and Prince, K. C.

Subjects
Physics - Atomic Physics
Abstract

Single photon laser enabled Auger decay (spLEAD) has been redicted theoretically [Phys. Rev. Lett. 111, 083004 (2013)] and here we report its first experimental observation in neon. Using coherent, bichromatic free-electron laser pulses, we have detected the process and coherently controlled the angular distribution of the emitted electrons by varying the phase difference between the two laser fields. Since spLEAD is highly sensitive to electron correlation, this is a promising method for probing both correlation and ultrafast hole migration in more complex systems., Comment: 5 pages, 3 figures

Published
2017
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5. Coherent control with a short-wavelength Free Electron Laser

Author

Prince, K. C., Allaria, E., Callegari, C., Cucini, R., De Ninno, G., Di Mitri, S., Diviacco, B., Ferrari, E., Finetti, P., Gauthier, D., Giannessi, L., Mahne, N., Penco, G., Plekan, O., Raimondi, L., Rebernik, P., Roussel, E., Svetina, C., Trovò, M., Zangrando, M., Negro, M., Carpeggiani, P., Reduzzi, M., Sansone, G., Grum-Grzhimailo, A. N., Gryzlova, E. V., Strakhova, S. I., Bartschat, K., Douguet, N., Venzke, J., Iablonskyi, D., Kumagai, Y., Takanashi, T., Ueda, K., Fischer, A., Coreno, M., Stienkemeier, F., Ovcharenko, Y., Mazza, T., and Meyer, M.

Subjects
Physics - Optics
Abstract

XUV and X-ray Free Electron Lasers (FELs) produce short wavelength pulses with high intensity, ultrashort duration, well-defined polarization and transverse coherence, and have been utilised for many experiments previously possible at long wavelengths only: multiphoton ionization, pumping an atomic laser, and four-wave mixing spectroscopy. However one important optical technique, coherent control, has not yet been demonstrated, because Self- Amplified Spontaneous Emission FELs have limited longitudinal coherence. Single-colour pulses from the FERMI seeded FEL are longitudinally coherent, and two-colour emission is predicted to be coherent. Here we demonstrate the phase correlation of two colours, and manipulate it to control an experiment. Light of wavelengths 63.0 and 31.5 nm ionized neon, and the asymmetry of the photoelectron angular distribution was controlled by adjusting the phase, with temporal resolution 3 attoseconds. This opens the door to new shortwavelength coherent control experiments with ultrahigh time resolution and chemical sensitivity.

Published
2017
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6. Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs

Author

Alonso-Mori, R, Asa, K, Bergmann, U, Brewster, AS, Chatterjee, R, Cooper, JK, Frei, HM, Fuller, FD, Goggins, E, Gul, S, Fukuzawa, H, Iablonskyi, D, Ibrahim, M, Katayama, T, Kroll, T, Kumagai, Y, McClure, BA, Messinger, J, Motomura, K, Nagaya, K, Nishiyama, T, Saracini, C, Sato, Y, Sauter, NK, Sokaras, D, Takanashi, T, Togashi, T, Ueda, K, Weare, WW, Weng, T-C, Yabashi, M, Yachandra, VK, Young, ID, Zouni, A, Kern, JF, and Yano, J

Subjects
Inorganic Chemistry, Chemical Sciences, Physical Chemistry, Catalysis, Crystallography, X-Ray, Electrons, Lasers, X-Rays, Chemical Physics, Chemical sciences
Abstract

The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.

Published
2016

7. Double-Electromagnetically Induced Transparency in a Y-type atomic system

Author

Safari, L., Iablonskyi, D., and Fratini, F.

Subjects
Physics - Atomic Physics
Abstract

We study the absorption and dispersion properties of a weak tunable probe field in a four-level Y-type atomic system driven by two strong laser (coupling) fields within the framework of density matrix formalism. It is found that the probe absorption profile displays double-electromagnetically induced transparency (double-EIT) and it is shown how to control it by changing the Rabi frequencies as well as the atom field detuning of the coupling fields., Comment: 8 pages

Published
2013
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8. Influence of an atomic resonance on the coherent control of the photoionization process

Author

Gryzlova, E. V., Carpeggiani, P., Popova, M. M., Kiselev, M. D., Douguet, N., Reduzzi, M., Negro, M., Comby, A., Ahmadi, H., Wanie, V., Castrovilli, M. C., Fischer, A., Eng-Johnsson, P., Meyer, M., Bartschat, K., Burkov, S. M., Csizmadia, T., Dumergue, M., Kuhn, S., Harshitha, N. G., Fule, M., Aeenehvand, F., Stienkemeier, F., Iablonskyi, D., Ueda, K., Finetti, P., Zangrando, M., Mahne, N., Ishikawa, K. L., Plekan, O., Prince, K. C., Allaria, E., Giannessi, L., Callegari, C., Grum-Grzhimailo, A. N., and Sansone, G.

Subjects
01.03. Fizikai tudományok, General Physics and Astronomy
Published
2022

9. Diffraction imaging of light induced dynamics in xenon-doped helium nanodroplets

Author

Langbehn, B, primary, Ovcharenko, Y, additional, Clark, A, additional, Coreno, M, additional, Cucini, R, additional, Demidovich, A, additional, Drabbels, M, additional, Finetti, P, additional, Di Fraia, M, additional, Giannessi, L, additional, Grazioli, C, additional, Iablonskyi, D, additional, LaForge, A C, additional, Nishiyama, T, additional, Oliver Álvarez de Lara, V, additional, Peltz, C, additional, Piseri, P, additional, Plekan, O, additional, Sander, K, additional, Ueda, K, additional, Fennel, T, additional, Prince, K C, additional, Stienkemeier, F, additional, Callegari, C, additional, Möller, T, additional, and Rupp, D, additional

Published
2022
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11. Suppression of thermal nanoplasma emission in clusters strongly ionized by hard x-rays

Author

Kumagai, Y. (Yoshiaki), Jurek, Z. (Zoltan), Xu, W. (Weiqing), Saxena, V. (Vikrant), Fukuzawa, H. (Hironobu), Motomura, K. (Koji), Iablonskyi, D. (Denys), Nagaya, K. (Kiyonobu), Wada, S.-i. (Shin-ichi), Ito, Y. (Yuta), Takanashi, T. (Tsukasa), Yamada, S. (Shuhei), Sakakibara, Y. (Yuta), Hiraki, T. N. (Toshiyuki Nishiyama), Umemoto, T. (Takayuki), Patanen, M. (Minna), Bozek, J. D. (John D), Dancus, I. (Ioan), Cernaianu, M. (Mihail), Miron, C. (Catalin), Bauer, T. (Tobias), Mucke, M. (Melanie), Kukk, E. (Edwin), Owada, S. (Shigeki), Togashi, T. (Tadashi), Tono, K. (Kensuke), Yabashi, M. (Makina), Son, S.-K. (Sang-Kil), Ziaja, B. (Beata), Santra, R. (Robin), Ueda, K. (Kiyoshi), Kumagai, Y. (Yoshiaki), Jurek, Z. (Zoltan), Xu, W. (Weiqing), Saxena, V. (Vikrant), Fukuzawa, H. (Hironobu), Motomura, K. (Koji), Iablonskyi, D. (Denys), Nagaya, K. (Kiyonobu), Wada, S.-i. (Shin-ichi), Ito, Y. (Yuta), Takanashi, T. (Tsukasa), Yamada, S. (Shuhei), Sakakibara, Y. (Yuta), Hiraki, T. N. (Toshiyuki Nishiyama), Umemoto, T. (Takayuki), Patanen, M. (Minna), Bozek, J. D. (John D), Dancus, I. (Ioan), Cernaianu, M. (Mihail), Miron, C. (Catalin), Bauer, T. (Tobias), Mucke, M. (Melanie), Kukk, E. (Edwin), Owada, S. (Shigeki), Togashi, T. (Tadashi), Tono, K. (Kensuke), Yabashi, M. (Makina), Son, S.-K. (Sang-Kil), Ziaja, B. (Beata), Santra, R. (Robin), and Ueda, K. (Kiyoshi)

Abstract

Using electron and ion spectroscopy, we studied the electron and nuclear dynamics in ~50 000-atom large krypton clusters, following excitation with an intense hard x-ray pulse. Beyond the single pulse experiment, we also present the results of a time-resolved, x-ray pump–near-infrared probe measurement that allows one to learn about the time evolution of the system. After core ionization of the atoms by x-ray photons, trapped Auger and secondary electrons form a nanoplasma in which the krypton ions are embedded, according to the already published scenario. While the ion data show expected features, the electron emission spectra miss the expected pump–probe delay-dependent enhancement except for a slight enhancement in the energy range below 2 eV. Theoretical simulations help to reveal that, due to the deep trapping potential of the ions during the long time expansion accompanied by electron–ion recombination, thermal emission from the transient nanoplasma becomes quenched.

Published
2021

12. Ultrafast Resonant Interatomic Coulombic Decay Induced by Quantum Fluid Dynamics

Author

LaForge, A. C., primary, Michiels, R., additional, Ovcharenko, Y., additional, Ngai, A., additional, Escartín, J. M., additional, Berrah, N., additional, Callegari, C., additional, Clark, A., additional, Coreno, M., additional, Cucini, R., additional, Di Fraia, M., additional, Drabbels, M., additional, Fasshauer, E., additional, Finetti, P., additional, Giannessi, L., additional, Grazioli, C., additional, Iablonskyi, D., additional, Langbehn, B., additional, Nishiyama, T., additional, Oliver, V., additional, Piseri, P., additional, Plekan, O., additional, Prince, K. C., additional, Rupp, D., additional, Stranges, S., additional, Ueda, K., additional, Sisourat, N., additional, Eloranta, J., additional, Pi, M., additional, Barranco, M., additional, Stienkemeier, F., additional, Möller, T., additional, and Mudrich, M., additional

Published
2021
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13. Autoionization dynamics of helium nanodroplets resonantly excited by intense XUV laser pulses

Author

Ovcharenko, Y., Laforge, A. C., Langbehn, B., Plekan, O., Cucini, R., Finetti, P., O'Keeffe, P., Iablonskyi, D., Nishiyama, T., Ueda, K., Piseri, P., Di Fraia, M., Richter, R., Coreno, M., Callegari, C., Prince, K. C., Stienkemeier, F., Möller, T., and Mudrich, M.

Subjects
He nanodroplets, nanoplasma, Physics::Atomic and Molecular Clusters, ddc:530, collective autoionization, interatomic Coulombic decay, Physics::Atomic Physics
Abstract

The ionization dynamics of helium droplets irradiated by intense, femtosecond extreme ultraviolet (XUV) pulses is investigated in detail by photoelectron spectroscopy. Helium droplets are resonantly excited to atomic-like 2p states with a photon energy of 21.5 eV and autoionize by interatomic Coulombic decay (ICD). A complex evolution of the electron spectra as a function of droplet size (250 to 106 He atoms per droplet) and XUV intensity (109-1012 W cm-2) is observed, ranging from narrow atomic-like peaks that are due to binary autoionization, to an unstructured feature characteristic of electron emission from a nanoplasma. The experimental results are analyzed and interpreted with the help of a numerical simulation based on rate equations taking into account all relevant processes - multi-step ionization, electronic relaxation, ICD, secondary inelastic collisions, desorption of electronically excited atoms, and collective autoionization (CAI).

Published
2020

14. Autoionization dynamics of helium nanodroplets resonantly excited by intense XUV laser pulses

Author

Ovcharenko, Y, primary, LaForge, A C, additional, Langbehn, B, additional, Plekan, O, additional, Cucini, R, additional, Finetti, P, additional, O’Keeffe, P, additional, Iablonskyi, D, additional, Nishiyama, T, additional, Ueda, K, additional, Piseri, P, additional, Di Fraia, M, additional, Richter, R, additional, Coreno, M, additional, Callegari, C, additional, Prince, K C, additional, Stienkemeier, F, additional, Möller, T, additional, and Mudrich, M, additional

Published
2020
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15. Autoionization dynamics of He nanodroplets resonantly excited by intense XUV laser pulses

Author

Ovcharenko, Yevheniy, LaForge, Aaron, Langbehn, B., Piekan, O., Cucini, R., Finetti, P., O'Keeffe, Patrick, Iablonskyi, D., Nishiyama, T., Ueda, K., Piseri, P., DiFraia, M., Richter, Robert, Coreno, M., Callegari, C., Prince, K.C., Stienkemeier, Frank, Møller, T, and Mudrich, Marcel

Subjects
Physics::Atomic and Molecular Clusters, FOS: Physical sciences, Physics::Atomic Physics, Physics - Atomic and Molecular Clusters, Atomic and Molecular Clusters (physics.atm-clus), 14J60 (Primary) 14F05, 14J26 (Secondary)
Abstract

The ionization dynamics of helium droplets in a wide size range from 220 to 10^6 He atoms irradiated with intense femtosecond extreme ultraviolet (XUV) pulses of 10^9 {\div} 10^{12} W/cm2 power density is investigated in detail by photoelectron spectroscopy. Helium droplets are resonantly excited in the photon energy range from ~ 21 eV (corresponding to the atomic 1s2s state) up to the atomic ionization potential (IP) at ~ 25 eV. A complex evolution of the electron spectra as a function of droplet size and XUV intensity is observed, ranging from atomic-like narrow peaks due to binary autoionization, to an unstructured feature characteristic of electron emission from a nanoplasma. The experimental results are analyzed and interpreted with the help of numerical simulations based on rate equations taking into account various processes such as multi-step ionization, interatomic Coulombic decay (ICD), secondary inelastic collisions, desorption of electronically excited atoms, collective autoionization (CAI) and further relaxation processes., Comment: 20 pages, 14 figures, 43 references

Published
2019

16. Full-dimensional theoretical description of vibrationally resolved valence-shell photoionization of H2O

Author

Engin S., González-Vázquez J., Maliyar G.G., Milosavljevi? A.R., Ono T., Nandi S., Iablonskyi D., Kooser K., Bozek J.D., Decleva P., Kukk E., Ueda K., Martín F. and We thank Dr. David Ayuso for useful discussions and technical support at the early stages of this research. This work was supported by the MINECO project FIS2016-77889-R and the ERC advanced Grant No. 290853—XCHEM—within the seventh framework programme of the European Union. We also acknowledge computer time from CCC-UAM and Marenostrum Supercomputer Center. Experimental data were obtained at the PLEIADES beamline at the SOLEIL Synchrotron, France (Proposal No. 20151311). F.M. acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (MINECO, Grant No. SEV-2016-0686) and the 'María de Maeztu' Programme for Units of Excellence in R&D (No. MDM-2014-0377). K.U. acknowledges the support by the Research Program of 'Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials' in 'Network Joint Research Center for Materials and Devices' and by the TAGEN project. E.K. and K.K. acknowledge financial support from the Academy of Finland.

Published
2019

18. Breakdown of ionic character of molecular alkali bromides in inner-valence photoionization.

Author

Karpenko, A., Iablonskyi, D., Urpelainen, S., Kettunen, J. A., Cao, W., Huttula, M., and Aksela, H.

Subjects
*ALKALIES, *BROMIDES, *PHOTOIONIZATION, *IONIZATION (Atomic physics), *MOLECULAR spectroscopy
Abstract

The inner-valence region of alkali bromide XBr (X=Li, Na, K, Rb) vapours has been studied experimentally by means of synchrotron radiation excited photoelectron spectroscopy. Experimental spectra were analyzed by comparing them with available theoretical results and previous experiments. Ionic character of alkali bromides is seen to change in the inner-valence region with increasing atomic number of the alkali atom. A mechanism involving mixing between Br 4s and Rb 4p orbitals has been suggested to account for the fine structure observed in inner-valence ionization region of RbBr. [ABSTRACT FROM AUTHOR]

Published
2014
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19. Observation and Control of Laser-Enabled Auger Decay

Author

Iablonskyi, D., primary, Ueda, K., additional, Ishikawa, K. L., additional, Kheifets, A. S., additional, Carpeggiani, P., additional, Reduzzi, M., additional, Ahmadi, H., additional, Comby, A., additional, Sansone, G., additional, Csizmadia, T., additional, Kuehn, S., additional, Ovcharenko, E., additional, Mazza, T., additional, Meyer, M., additional, Fischer, A., additional, Callegari, C., additional, Plekan, O., additional, Finetti, P., additional, Allaria, E., additional, Ferrari, E., additional, Roussel, E., additional, Gauthier, D., additional, Giannessi, L., additional, and Prince, K. C., additional

Published
2017
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20. Time-Resolved Measurement of Interatomic Coulombic Decay Induced by Two-Photon Double Excitation of Ne2

Author

Takanashi, T., primary, Golubev, N. V., additional, Callegari, C., additional, Fukuzawa, H., additional, Motomura, K., additional, Iablonskyi, D., additional, Kumagai, Y., additional, Mondal, S., additional, Tachibana, T., additional, Nagaya, K., additional, Nishiyama, T., additional, Matsunami, K., additional, Johnsson, P., additional, Piseri, P., additional, Sansone, G., additional, Dubrouil, A., additional, Reduzzi, M., additional, Carpeggiani, P., additional, Vozzi, C., additional, Devetta, M., additional, Negro, M., additional, Faccialà, D., additional, Calegari, F., additional, Trabattoni, A., additional, Castrovilli, M. C., additional, Ovcharenko, Y., additional, Mudrich, M., additional, Stienkemeier, F., additional, Coreno, M., additional, Alagia, M., additional, Schütte, B., additional, Berrah, N., additional, Plekan, O., additional, Finetti, P., additional, Spezzani, C., additional, Ferrari, E., additional, Allaria, E., additional, Penco, G., additional, Serpico, C., additional, De Ninno, G., additional, Diviacco, B., additional, Di Mitri, S., additional, Giannessi, L., additional, Jabbari, G., additional, Prince, K. C., additional, Cederbaum, L. S., additional, Demekhin, Ph. V., additional, Kuleff, A. I., additional, and Ueda, K., additional

Published
2017
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21. Slow Interatomic Coulombic Decay of Multiply Excited Neon Clusters

Author

Iablonskyi, D., primary, Nagaya, K., additional, Fukuzawa, H., additional, Motomura, K., additional, Kumagai, Y., additional, Mondal, S., additional, Tachibana, T., additional, Takanashi, T., additional, Nishiyama, T., additional, Matsunami, K., additional, Johnsson, P., additional, Piseri, P., additional, Sansone, G., additional, Dubrouil, A., additional, Reduzzi, M., additional, Carpeggiani, P., additional, Vozzi, C., additional, Devetta, M., additional, Negro, M., additional, Calegari, F., additional, Trabattoni, A., additional, Castrovilli, M. C., additional, Faccialà, D., additional, Ovcharenko, Y., additional, Möller, T., additional, Mudrich, M., additional, Stienkemeier, F., additional, Coreno, M., additional, Alagia, M., additional, Schütte, B., additional, Berrah, N., additional, Kuleff, A. I., additional, Jabbari, G., additional, Callegari, C., additional, Plekan, O., additional, Finetti, P., additional, Spezzani, C., additional, Ferrari, E., additional, Allaria, E., additional, Penco, G., additional, Serpico, C., additional, De Ninno, G., additional, Nikolov, I., additional, Diviacco, B., additional, Di Mitri, S., additional, Giannessi, L., additional, Prince, K. C., additional, and Ueda, K., additional

Published
2016
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22. Interatomic Coulombic decay cascades in multiply excited neon clusters

Author

Nagaya, K., primary, Iablonskyi, D., additional, Golubev, N. V., additional, Matsunami, K., additional, Fukuzawa, H., additional, Motomura, K., additional, Nishiyama, T., additional, Sakai, T., additional, Tachibana, T., additional, Mondal, S., additional, Wada, S., additional, Prince, K. C., additional, Callegari, C., additional, Miron, C., additional, Saito, N., additional, Yabashi, M., additional, Demekhin, Ph. V., additional, Cederbaum, L. S., additional, Kuleff, A. I., additional, Yao, M., additional, and Ueda, K., additional

Published
2016
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23. Interatomic Coulombic Decay Processes after Multiple Valence Excitations in Ne Clusters

Author

Iablonskyi, D., Nagaya, K., Fukuzawa, H., Motomura, K., Kumagai, Y., Mondal, S., Tachibana, T., Takanashi, T., Nishiyama, T., Matsunami, K., Johnsson, P., Piseri, P., Sansone, G., Dubrouil, A., Reduzzi, M., Carpeggiani, P., Vozzi, C., Devetta, M., Negro, M., Faccialà, D., Calegari, F., Trabattoni, A., Castrovilli, M., Ovcharenko, Y., Möller, T., Mudrich, M., Stienkemeier, F., Coreno, M., Alagia, M., Schütte, B., Berrah, N., Callegari, C., Plekan, O., Finetti, P., Spezzani, C., Ferrari, E., Allaria, E., Penco, G., Serpico, C., De Ninno, G., Diviacco, B., Di Mitri, S., Giannessi, L., Prince, K. C., Yao, M., and Ueda, K.

Subjects
Condensed Matter::Materials Science, Condensed Matter::Other, Quantitative Biology::Tissues and Organs, Physics::Atomic and Molecular Clusters, ddc:530, Physics::Atomic Physics
Abstract

We present a comprehensive analysis of autoionization processes in Ne clusters (~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.

Published
2015

24. Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs

Author

Alonso-Mori, R., Asa, K., Bergmann, U., Brewster, A. S., Chatterjee, R., Cooper, J. K., Frei, H. M., Fuller, F. D., Goggins, E., Gul, S., Fukuzawa, H., Iablonskyi, D., Ibrahim, M., Katayama, T., Kroll, T., Kumagai, Y., McClure, B. A., Messinger, Johannes, Motomura, K., Nagaya, K., Nishiyama, T., Saracini, C., Sato, Y., Sauter, N. K., Sokaras, D., Takanashi, T., Togashi, T., Ueda, K., Weare, W. W., Weng, T-C, Yabashi, M., Yachandra, V. K., Young, I. D., Zouni, A., Kern, J. F., Yano, J., Alonso-Mori, R., Asa, K., Bergmann, U., Brewster, A. S., Chatterjee, R., Cooper, J. K., Frei, H. M., Fuller, F. D., Goggins, E., Gul, S., Fukuzawa, H., Iablonskyi, D., Ibrahim, M., Katayama, T., Kroll, T., Kumagai, Y., McClure, B. A., Messinger, Johannes, Motomura, K., Nagaya, K., Nishiyama, T., Saracini, C., Sato, Y., Sauter, N. K., Sokaras, D., Takanashi, T., Togashi, T., Ueda, K., Weare, W. W., Weng, T-C, Yabashi, M., Yachandra, V. K., Young, I. D., Zouni, A., Kern, J. F., and Yano, J.

Abstract

The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.

Published
2016
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25. Interatomic Coulombic decay cascades in multiply excited neon clusters.

Author

30273436, Nagaya, K, Iablonskyi, D, Golubev, N. V, Matsunami, K, Fukuzawa, H, Motomura, K, Nishiyama, T, Sakai, T, Tachibana, T, Mondal, S, Wada, S, Prince, K. C, Callegari, C, Miron, C, Saito, N, Yabashi, M, Demekhin, Ph. V, Cederbaum, L. S, Kuleff, A. I, Yao, M, Ueda, K, 30273436, Nagaya, K, Iablonskyi, D, Golubev, N. V, Matsunami, K, Fukuzawa, H, Motomura, K, Nishiyama, T, Sakai, T, Tachibana, T, Mondal, S, Wada, S, Prince, K. C, Callegari, C, Miron, C, Saito, N, Yabashi, M, Demekhin, Ph. V, Cederbaum, L. S, Kuleff, A. I, Yao, M, and Ueda, K

Abstract

In high-intensity laser light, matter can be ionized by direct multiphoton absorption even at photon energies below the ionization threshold. However on tuning the laser to the lowest resonant transition, the system becomes multiply excited, and more efficient, indirect ionization pathways become operative. These mechanisms are known as interatomic Coulombic decay (ICD), where one of the species de-excites to its ground state, transferring its energy to ionize another excited species. Here we show that on tuning to a higher resonant transition, a previously unknown type of interatomic Coulombic decay, intra-Rydberg ICD occurs. In it, de-excitation of an atom to a close-lying Rydberg state leads to electron emission from another neighbouring Rydberg atom. Moreover, systems multiply excited to higher Rydberg states will decay by a cascade of such processes, producing even more ions. The intra-Rydberg ICD and cascades are expected to be ubiquitous in weakly-bound systems exposed to high-intensity resonant radiation.

Published
2016

26. Coherent control with a short-wavelength free-electron laser

Author

Prince, K. C., primary, Allaria, E., additional, Callegari, C., additional, Cucini, R., additional, De Ninno, G., additional, Di Mitri, S., additional, Diviacco, B., additional, Ferrari, E., additional, Finetti, P., additional, Gauthier, D., additional, Giannessi, L., additional, Mahne, N., additional, Penco, G., additional, Plekan, O., additional, Raimondi, L., additional, Rebernik, P., additional, Roussel, E., additional, Svetina, C., additional, Trovò, M., additional, Zangrando, M., additional, Negro, M., additional, Carpeggiani, P., additional, Reduzzi, M., additional, Sansone, G., additional, Grum-Grzhimailo, A. N., additional, Gryzlova, E. V., additional, Strakhova, S. I., additional, Bartschat, K., additional, Douguet, N., additional, Venzke, J., additional, Iablonskyi, D., additional, Kumagai, Y., additional, Takanashi, T., additional, Ueda, K., additional, Fischer, A., additional, Coreno, M., additional, Stienkemeier, F., additional, Ovcharenko, Y., additional, Mazza, T., additional, and Meyer, M., additional

Published
2016
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27. Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs

Author

Alonso-Mori, R., primary, Asa, K., additional, Bergmann, U., additional, Brewster, A. S., additional, Chatterjee, R., additional, Cooper, J. K., additional, Frei, H. M., additional, Fuller, F. D., additional, Goggins, E., additional, Gul, S., additional, Fukuzawa, H., additional, Iablonskyi, D., additional, Ibrahim, M., additional, Katayama, T., additional, Kroll, T., additional, Kumagai, Y., additional, McClure, B. A., additional, Messinger, J., additional, Motomura, K., additional, Nagaya, K., additional, Nishiyama, T., additional, Saracini, C., additional, Sato, Y., additional, Sauter, N. K., additional, Sokaras, D., additional, Takanashi, T., additional, Togashi, T., additional, Ueda, K., additional, Weare, W. W., additional, Weng, T.-C., additional, Yabashi, M., additional, Yachandra, V. K., additional, Young, I. D., additional, Zouni, A., additional, Kern, J. F., additional, and Yano, J., additional

Published
2016
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28. Interatomic Coulombic Decay Processes after Multiple Valence Excitations in Ne Clusters

Author

Iablonskyi, D, primary, Nagaya, K, additional, Fukuzawa, H, additional, Motomura, K, additional, Kumagai, Y, additional, Mondal, S, additional, Tachibana, T, additional, Takanashi, T, additional, Nishiyama, T, additional, Matsunami, K, additional, Johnsson, P, additional, Piseri, P, additional, Sansone, G, additional, Dubrouil, A, additional, Reduzzi, M, additional, Carpeggiani, P, additional, Vozzi, C, additional, Devetta, M, additional, Negro, M, additional, Faccialà, D, additional, Calegari, F, additional, Trabattoni, A, additional, Castrovilli, M, additional, Ovcharenko, Y, additional, Möller, T, additional, Mudrich, M, additional, Stienkemeier, F, additional, Coreno, M, additional, Alagia, M, additional, Schütte, B, additional, Berrah, N, additional, Callegari, C, additional, Plekan, O, additional, Finetti, P, additional, Spezzani, C, additional, Ferrari, E, additional, Allaria, E, additional, Penco, G, additional, Serpico, C, additional, De Ninno, G, additional, Diviacco, B, additional, Di Mitri, S, additional, Giannessi, L, additional, Prince, K C, additional, Yao, M, additional, and Ueda, K, additional

Published
2015
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32. Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers

Author

Avgoulea, M, primary, Gangrsky, Yu P, additional, Marinova, K P, additional, Zemlyanoi, S G, additional, Fritzsche, S, additional, Iablonskyi, D, additional, Barbieri, C, additional, Simpson, E C, additional, Stevenson, P D, additional, Billowes, J, additional, Campbell, P, additional, Cheal, B, additional, Tordoff, B, additional, Bissell, M L, additional, Forest, D H, additional, Gardner, M D, additional, Tungate, G, additional, Huikari, J, additional, Nieminen, A, additional, Penttilä, H, additional, and Äystö, J, additional

Published
2011
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33. Changes in the 5d photoionization spectra between atomic and solid Pb.

Author

Iablonskyi, D., Patanen, M., Aksela, S., and Aksela, H.

Subjects
*PHOTOIONIZATION, *LEAD, *SPECTRUM analysis, *BINDING energy, *ELECTRON spin, *CHARGE transfer
Abstract

The Pb 5d photoionization spectrum of free atoms and the corresponding solid state have been measured simultaneously in one experiment. In addition to the 5

Published
2012
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34. Slow Interatomic Coulombic Decay of Multiply Excited Neon Clusters

Author

Iablonskyi, D., Nagaya, K., Fukuzawa, H., Motomura, K., Kumagai, Y., Mondal, S., Tachibana, T., Takanashi, T., Nishiyama, T., Matsunami, K., Johnsson, P., Piseri, P., Sansone, G., Dubrouil, A., Reduzzi, M., Carpeggiani, P., Vozzi, C., Devetta, M., Negro, M., Calegari, F., Trabattoni, A., Castrovilli, M. C., Faccialà, D., Ovcharenko, Y., Möller, T., Mudrich, M., Stienkemeier, F., Coreno, M., Alagia, M., Schütte, B., Berrah, N., Kuleff, A. I., Jabbari, G., Callegari, C., Plekan, O., Finetti, P., Spezzani, C., Ferrari, E., Allaria, E., Penco, G., Serpico, C., De Ninno, G., Nikolov, I., Diviacco, B., Di Mitri, S., Giannessi, L., Prince, K. C., and Ueda, K.

Subjects
3. Good health
Abstract

Physical review letters 117(27), 276806 (2016). doi:10.1103/PhysRevLett.117.276806, 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 betweenat least two neighboring excited atoms. Benefiting from the precise tunability and narrow bandwidth ofseeded FEL radiation, specific sites of the Ne clusters were probed. We found that the relaxation of clustersurface atoms proceeds via a sequence of interatomic or intermolecular Coulombic decay (ICD) processeswhile ICD of bulk atoms is additionally affected by the surrounding excited medium via inelastic electronscattering. For both cases, cluster excitations relax to atomic states prior to ICD, showing that this kind ofICD is rather slow (picosecond range). Controlling the average number of excitations per cluster via theFEL intensity allows a coarse tuning of the ICD rate., Published by APS, College Park, Md.

35. Time-Resolved Measurement of Interatomic Coulombic Decay Induced by Two-Photon Double Excitation of Ne 2

Author

Takanashi, T., Golubev, N. V., Callegari, C., Fukuzawa, H., Motomura, K., Iablonskyi, D., Kumagai, Y., Mondal, S., Tachibana, T., Nagaya, K., Nishiyama, T., Matsunami, K., Johnsson, P., Piseri, P., Sansone, G., Dubrouil, A., Reduzzi, M., Carpeggiani, P., Vozzi, C., Devetta, M., Negro, M., Faccialà, D., Calegari, F., Trabattoni, A., Castrovilli, M. C., Ovcharenko, Y., Mudrich, M., Stienkemeier, F., Coreno, M., Alagia, M., Schütte, B., Berrah, N., Plekan, O., Finetti, P., Spezzani, C., Ferrari, E., Allaria, E., Penco, G., Serpico, C., De Ninno, G., Diviacco, B., Di Mitri, S., Giannessi, L., Jabbari, G., Prince, K. C., Cederbaum, L. S., Demekhin, Ph. V., Kuleff, A. I., and Ueda, K.

Subjects
7. Clean energy
Abstract

Physical review letters 118(3), 033202 (2017). doi:10.1103/PhysRevLett.118.033202, The hitherto unexplored two-photon doubly excited states [Ne*$(2p−^13s)]_2$ were experimentallyidentified using the seeded, fully coherent, intense extreme ultraviolet free-electron laser FERMI. Thesestates undergo ultrafast interatomic Coulombic decay (ICD), which predominantly produces singly ionizeddimers. In order to obtain the rate of ICD, the resulting yield of $Ne^+_2$ ions was recorded as a function ofdelay 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 goodagreement with $ab$ $initio$ quantum mechanical calculations., Published by APS, College Park, Md.

36. Wireless and battery-operatable IoT platform for cost-effective detection of fouling in industrial equipment.

Author

Korsimaa J, Weber M, Salminen P, Mustonen J, Iablonskyi D, Hæggström E, Klami A, and Salmi A

Abstract

We present a novel internet of things (IoT) sensing platform that uses helical propagation paths of ultrasonic guided waves (UGWs) for structural health monitoring. This wireless sensor network comprises multiple identical sensor units that communicate with a host PC. The units have dedicated hardware to both generate and receive ultrasonic signals, as well as RF signals for use in triggering the sensors. The system was developed for monitoring and sensing pipelines and similar structures in real-time to facilitate interactive sensing. For accurate sensing with a limited number of arbitrarily scattered sensors, we obtain information from all sensor pairs and analyze helical propagation paths in addition to the commonly used shortest paths. UGWs can propagate long distances along the walls of pipelines, and their propagation velocity depends directly on the thickness of the waveguide, and is affected by energy leakage and mass loading. In this paper, we evaluated the network by utilizing it to detect fouling. The network could be adapted for further ultrasonic measurement tasks, e.g., measuring wall thicknesses or monitoring defects with pulse-echo methods., (© 2024. The Author(s).)

Published
2024
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37. Disentangling the evolution of electrons and holes in photoexcited ZnO nanoparticles.

Author

Milne CJ, Nagornova N, Pope T, Chen HY, Rossi T, Szlachetko J, Gawelda W, Britz A, van Driel TB, Sala L, Ebner S, Katayama T, Southworth SH, Doumy G, March AM, Lehmann CS, Mucke M, Iablonskyi D, Kumagai Y, Knopp G, Motomura K, Togashi T, Owada S, Yabashi M, Nielsen MM, Pajek M, Ueda K, Abela R, Penfold TJ, and Chergui M

Abstract

The evolution of charge carriers in photoexcited room temperature ZnO nanoparticles in solution is investigated using ultrafast ultraviolet photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy, and ab initio molecular dynamics (MD) simulations. The photoluminescence is excited at 4.66 eV, well above the band edge, and shows that electron cooling in the conduction band and exciton formation occur in <500 fs, in excellent agreement with theoretical predictions. The x-ray absorption measurements, obtained upon excitation close to the band edge at 3.49 eV, are sensitive to the migration and trapping of holes. They reveal that the 2 ps transient largely reproduces the previously reported transient obtained at 100 ps time delay in synchrotron studies. In addition, the x-ray absorption signal is found to rise in ∼1.4 ps, which we attribute to the diffusion of holes through the lattice prior to their trapping at singly charged oxygen vacancies. Indeed, the MD simulations show that impulsive trapping of holes induces an ultrafast expansion of the cage of Zn atoms in <200 fs, followed by an oscillatory response at a frequency of ∼100 cm -1 , which corresponds to a phonon mode of the system involving the Zn sub-lattice., Competing Interests: The authors have no conflicts to disclose., (© 2023 Author(s).)

Published
2023
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38. Full-dimensional theoretical description of vibrationally resolved valence-shell photoionization of H 2 O.

Author

Engin S, González-Vázquez J, Maliyar GG, Milosavljević AR, Ono T, Nandi S, Iablonskyi D, Kooser K, Bozek JD, Decleva P, Kukk E, Ueda K, and Martín F

Abstract

We have performed a full-dimensional theoretical study of vibrationally resolved photoelectron emission from the valence shell of the water molecule by using an extension of the static-exchange density functional theory that accounts for ionization as well as for vibrational motion in the symmetric stretching, antisymmetric stretching, and bending modes. At variance with previous studies performed in centrosymmetric molecules, where vibrationally resolved spectra are mostly dominated by the symmetric stretching mode, in the present case, all three modes contribute to the calculated spectra, including intermode couplings. We have found that diffraction of the ejected electron by the various atomic centers is barely visible in the ratios between vibrationally resolved photoelectron spectra corresponding to different vibrational states of the remaining H 2 O + cation (the so-called v -ratios), in contrast to the prominent oscillations observed in K-shell ionization of centrosymmetric molecules, including those that only contain hydrogen atoms around the central atoms, e.g., CH 4 . To validate the conclusions of our work, we have carried out synchrotron radiation experiments at the SOLEIL synchrotron and determined photoelectron spectra and v -ratios for H 2 O in a wide range of photon energies, from threshold up to 150 eV. The agreement with the theoretical predictions is good.

Published
2019
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39. Real-time observation of X-ray-induced intramolecular and interatomic electronic decay in CH 2 I 2 .

Author

Fukuzawa H, Takanashi T, Kukk E, Motomura K, Wada SI, Nagaya K, Ito Y, Nishiyama T, Nicolas C, Kumagai Y, Iablonskyi D, Mondal S, Tachibana T, You D, Yamada S, Sakakibara Y, Asa K, Sato Y, Sakai T, Matsunami K, Umemoto T, Kariyazono K, Kajimoto S, Sotome H, Johnsson P, Schöffler MS, Kastirke G, Kooser K, Liu XJ, Asavei T, Neagu L, Molodtsov S, Ochiai K, Kanno M, Yamazaki K, Owada S, Ogawa K, Katayama T, Togashi T, Tono K, Yabashi M, Ghosh A, Gokhberg K, Cederbaum LS, Kuleff AI, Fukumura H, Kishimoto N, Rudenko A, Miron C, Kono H, and Ueda K

Abstract

The increasing availability of X-ray free-electron lasers (XFELs) has catalyzed the development of single-object structural determination and of structural dynamics tracking in real-time. Disentangling the molecular-level reactions triggered by the interaction with an XFEL pulse is a fundamental step towards developing such applications. Here we report real-time observations of XFEL-induced electronic decay via short-lived transient electronic states in the diiodomethane molecule, using a femtosecond near-infrared probe laser. We determine the lifetimes of the transient states populated during the XFEL-induced Auger cascades and find that multiply charged iodine ions are issued from short-lived (∼20 fs) transient states, whereas the singly charged ones originate from significantly longer-lived states (∼100 fs). We identify the mechanisms behind these different time scales: contrary to the short-lived transient states which relax by molecular Auger decay, the long-lived ones decay by an interatomic Coulombic decay between two iodine atoms, during the molecular fragmentation.

Published
2019
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40. Three-Dimensional Shapes of Spinning Helium Nanodroplets.

Author

Langbehn B, Sander K, Ovcharenko Y, Peltz C, Clark A, Coreno M, Cucini R, Drabbels M, Finetti P, Di Fraia M, Giannessi L, Grazioli C, Iablonskyi D, LaForge AC, Nishiyama T, Oliver Álvarez de Lara V, Piseri P, Plekan O, Ueda K, Zimmermann J, Prince KC, Stienkemeier F, Callegari C, Fennel T, Rupp D, and Möller T

Abstract

A significant fraction of superfluid helium nanodroplets produced in a free-jet expansion has been observed to gain high angular momentum resulting in large centrifugal deformation. We measured single-shot diffraction patterns of individual rotating helium nanodroplets up to large scattering angles using intense extreme ultraviolet light pulses from the FERMI free-electron laser. Distinct asymmetric features in the wide-angle diffraction patterns enable the unique and systematic identification of the three-dimensional droplet shapes. The analysis of a large data set allows us to follow the evolution from axisymmetric oblate to triaxial prolate and two-lobed droplets. We find that the shapes of spinning superfluid helium droplets exhibit the same stages as classical rotating droplets while the previously reported metastable, oblate shapes of quantum droplets are not observed. Our three-dimensional analysis represents a valuable landmark for clarifying the interrelation between morphology and superfluidity on the nanometer scale.

Published
2018
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41. Radiation-Induced Chemical Dynamics in Ar Clusters Exposed to Strong X-Ray Pulses.

Author

Kumagai Y, Jurek Z, Xu W, Fukuzawa H, Motomura K, Iablonskyi D, Nagaya K, Wada SI, Mondal S, Tachibana T, Ito Y, Sakai T, Matsunami K, Nishiyama T, Umemoto T, Nicolas C, Miron C, Togashi T, Ogawa K, Owada S, Tono K, Yabashi M, Son SK, Ziaja B, Santra R, and Ueda K

Abstract

We show that electron and ion spectroscopy reveals the details of the oligomer formation in Ar clusters exposed to an x-ray free electron laser (XFEL) pulse, i.e., chemical dynamics triggered by x rays. With guidance from a dedicated molecular dynamics simulation tool, we find that van der Waals bonding, the oligomer formation mechanism, and charge transfer among the cluster constituents significantly affect ionization dynamics induced by an XFEL pulse of moderate fluence. Our results clearly demonstrate that XFEL pulses can be used not only to "damage and destroy" molecular assemblies but also to modify and transform their molecular structure. The accuracy of the predictions obtained makes it possible to apply the cluster spectroscopy, in connection with the respective simulations, for estimation of the XFEL pulse fluence in the fluence regime below single-atom multiple-photon absorption, which is hardly accessible with other diagnostic tools.

Published
2018
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42. Ultrafast Coulomb explosion of a diiodomethane molecule induced by an X-ray free-electron laser pulse.

Author

Takanashi T, Nakamura K, Kukk E, Motomura K, Fukuzawa H, Nagaya K, Wada SI, Kumagai Y, Iablonskyi D, Ito Y, Sakakibara Y, You D, Nishiyama T, Asa K, Sato Y, Umemoto T, Kariyazono K, Ochiai K, Kanno M, Yamazaki K, Kooser K, Nicolas C, Miron C, Asavei T, Neagu L, Schöffler M, Kastirke G, Liu XJ, Rudenko A, Owada S, Katayama T, Togashi T, Tono K, Yabashi M, Kono H, and Ueda K

Abstract

Coulomb explosion of diiodomethane CH 2 I 2 molecules irradiated by ultrashort and intense X-ray pulses from SACLA, the Japanese X-ray free electron laser facility, was investigated by multi-ion coincidence measurements and self-consistent charge density-functional-based tight-binding (SCC-DFTB) simulations. The diiodomethane molecule, containing two heavy-atom X-ray absorbing sites, exhibits a rather different charge generation and nuclear motion dynamics compared to iodomethane CH 3 I with only a single heavy atom, as studied earlier. We focus on charge creation and distribution in CH 2 I 2 in comparison to CH 3 I. The release of kinetic energy into atomic ion fragments is also studied by comparing SCC-DFTB simulations with the experiment. Compared to earlier simulations, several key enhancements are made, such as the introduction of a bond axis recoil model, where vibrational energy generated during charge creation processes induces only bond stretching or shrinking. We also propose an analytical Coulomb energy partition model to extract the essential mechanism of Coulomb explosion of molecules from the computed and the experimentally measured kinetic energies of fragment atomic ions by partitioning each pair Coulomb interaction energy into two ions of the pair under the constraint of momentum conservation. Effective internuclear distances assigned to individual fragment ions at the critical moment of the Coulomb explosion are then estimated from the average kinetic energies of the ions. We demonstrate, with good agreement between the experiment and the SCC-DFTB simulation, how the more heavily charged iodine fragments and their interplay define the characteristic features of the Coulomb explosion of CH 2 I 2 . The present study also confirms earlier findings concerning the magnitude of bond elongation in the ultrashort X-ray pulse duration, showing that structural damage to all but C-H bonds does not develop to a noticeable degree in the pulse length of ∼10 fs.

Published
2017
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43. Valence photoelectron spectra of alkali bromides calculated within the propagator theory.

Author

Karpenko A, Iablonskyi D, and Aksela H

Subjects
Photoelectron Spectroscopy, Bromides chemistry, Metals, Alkali chemistry, Quantum Theory
Abstract

The valence ionization spectra covering the binding energy range 0-45 eV of alkali bromide XBr (X = Li, Na, K, Rb) vapors are studied within the framework of the propagator theory. Relativistic Algebraic Diagrammatic Construction calculations have been carried out in order to investigate photoionization processes and to describe molecular electronic structure. Theoretical results are compared with available experimental data.

Published
2013
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