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2023
"De l’ultra-rapide à l’ultra-intense : de nouveaux champs d’études"
Dobosz Dufrenoy S, Ruchon T, Vincenti H, Bresteau D, Monot P, Marroux H, Geneaux R, Hricovini K & Salieres P, Photoniques. (118), pp. 40-45. (2023).
Abstract: Le développement spectaculaire des lasers de puissance ces trente dernières années a ouvert de nouveaux champs d’études : la science attoseconde d’une part, l’optique relativiste d’autre part. Nous illustrons les nouvelles perspectives ouvertes dans divers domaines de la physique, la chimie, la médecine ou la science des matériaux à partir d’études effectuées sur les plateformes ATTOLab et UHI100 du Laboratoire Interactions, Dynamiques et Lasers (LIDYL) du CEA Paris-Saclay.
BibTeX:
@article{dufrenoy2023ultra,
  author = {Dobosz Dufrenoy, Sandrine and Ruchon, Thierry and Vincenti, Henri and Bresteau, David and Monot, Pascal and Marroux, Hugo and Geneaux, Romain and Hricovini, Karol and Salieres, Pascal},
  title = {De l’ultra-rapide à l’ultra-intense : de nouveaux champs d’études},
  journal = {Photoniques},
  year = {2023},
  number = {118},
  pages = {40--45},
  url = {https://doi.org/10.1051/photon/202311840},
  doi = {10.1051/photon/202311840}
}
"Ionization of Xenon Clusters by a Hard X-ray Laser Pulse"
Kumagai Y, Xu W, Asa K, Nishiyama TH, Motomura K, Wada S-i, Iablonskyi D, Mondal S, Tachibana T, Ito Y, Sakai T, Matsunami K, Umemoto T, Nicolas C, Miron C, Togashi T, Ogawa K, Owada S, Tono K, Yabashi M, Fukuzawa H, Nagaya K & Ueda K, Applied Sciences. Vol. 13(4), (2023).
Abstract: Ultrashort pulse X-ray free electron lasers (XFFLs) provided us with an unprecedented regime of X-ray intensities, revolutionizing ultrafast structure determination and paving the way to the novel field of non-linear X-ray optics. While pioneering studies revealed the formation of a nanoplasma following the interaction of an XFEL pulse with nanometer-scale matter, nanoplasma formation and disintegration processes are not completely understood, and the behavior of trapped electrons in the electrostatic potential of highly charged species is yet to be decrypted. Here we report the behavior of the nanoplasma created by a hard X-ray pulse interacting with xenon clusters by using electron and ion spectroscopy. To obtain a deep insight into the formation and disintegration of XFEL-ignited nanoplasma, we studied the XFEL-intensity and cluster-size dependencies of the ionization dynamics. We also present the time-resolved data obtained by a near-infrared (NIR) probe pulse in order to experimentally track the time evolution of plasma electrons distributed in the XFEL-ignited nanoplasma. We observed an unexpected time delay dependence of the ion yield enhancement due to the NIR pulse heating, which demonstrates that the plasma electrons within the XFEL-ignited nanoplasma are inhomogeneously distributed in space.
BibTeX:
@other{Kumagai2023,
  author = {Kumagai, Yoshiaki and Xu, Weiqing and Asa, Kazuki and Nishiyama, Toshiyuki H. and Motomura, Koji and Wada, Shin-ichi and Iablonskyi, Denys and Mondal, Subhendu and Tachibana, Tetsuya and Ito, Yuta and Sakai, Tsukasa and Matsunami, Kenji and Umemoto, Takayuki and Nicolas, Christophe and Miron, Catalin and Togashi, Tadashi and Ogawa, Kanade and Owada, Shigeki and Tono, Kensuke and Yabashi, Makina and Fukuzawa, Hironobu and Nagaya, Kiyonobu and Ueda, Kiyoshi},
  title = {Ionization of Xenon Clusters by a Hard X-ray Laser Pulse},
  journal = {Applied Sciences},
  year = {2023},
  volume = {13},
  number = {4},
  url = {https://www.mdpi.com/2076-3417/13/4/2176},
  doi = {10.3390/app13042176}
}
2022
"Observation of Rabi dynamics with a short-wavelength free-electron laser"
Nandi S, Olofsson E, Bertolino M, Carlström S, Zapata F, Busto D, Callegari C, Di Fraia M, Eng-Johnsson P, Feifel R, Gallician G, Gisselbrecht M, Maclot S, Neoricic L, Peschel J, Plekan O, Prince KC, Squibb RJ, Zhong S, Demekhin PV, Meyer M, Miron C, Badano L, Danailov MB, Giannessi L, Manfredda M, Sottocorona F, Zangrando M & Dahlström JM, Nature., August, 2022. Vol. 608(7923), pp. 488-493.(2022).
Abstract: Rabi oscillations are periodic modulations of populations in two-level systems interacting with a time-varying field1. They are ubiquitous in physics with applications in different areas such as photonics2, nano-electronics3, electron microscopy4 and quantum information5. While the theory developed by Rabi was intended for fermions in gyrating magnetic fields, Autler and Townes realized that it could also be used to describe coherent light-matter interactions within the rotating-wave approximation6. Although intense nanometre-wavelength light sources have been available for more than a decade7-9, Rabi dynamics at such short wavelengths has not been directly observed. Here we show that femtosecond extreme-ultraviolet pulses from a seeded free-electron laser10 can drive Rabi dynamics between the ground state and an excited state in helium atoms. The measured photoelectron signal reveals an Autler-Townes doublet and an avoided crossing, phenomena that are both fundamental to coherent atom-field interactions11. Using an analytical model derived from perturbation theory on top of the Rabi model, we find that the ultrafast build-up of the doublet structure carries the signature of a quantum interference effect between resonant and non-resonant photoionization pathways. Given the recent availability of intense attosecond12 and few-femtosecond13 extreme-ultraviolet pulses, our results unfold opportunities to carry out ultrafast manipulation of coherent processes at short wavelengths using free-electron lasers.
BibTeX:
@article{Nandi2022,
  author = {Nandi, Saikat and Olofsson, Edvin and Bertolino, Mattias and Carlström, Stefanos and Zapata, Felipe and Busto, David and Callegari, Carlo and Di Fraia, Michele and Eng-Johnsson, Per and Feifel, Raimund and Gallician, Guillaume and Gisselbrecht, Mathieu and Maclot, Sylvain and Neoricic, Lana and Peschel, Jasper and Plekan, Oksana and Prince, Kevin C. and Squibb, Richard J. and Zhong, Shiyang and Demekhin, Philipp V. and Meyer, Michael and Miron, Catalin and Badano, Laura and Danailov, Miltcho B. and Giannessi, Luca and Manfredda, Michele and Sottocorona, Filippo and Zangrando, Marco and Dahlström, Jan Marcus},
  title = {Observation of Rabi dynamics with a short-wavelength free-electron laser},
  journal = {Nature},
  year = {2022},
  volume = {608},
  number = {7923},
  pages = {488--493},
  url = {https://doi.org/10.1038/s41586-022-04948-y},
  doi = {10.1038/s41586-022-04948-y}
}
2021
"Crystallization kinetics of atomic crystals revealed by a single-shot and single-particle X-ray diffraction experiment"
Niozu A, Kumagai Y, Hiraki TN, Fukuzawa H, Motomura K, Bucher M, Asa K, Sato Y, Ito Y, You D, Ono T, Li Y, Kukk E, Miron C, Neagu L, Callegari C, Di Fraia M, Rossi G, Galli DE, Pincelli T, Colombo A, Owada S, Tono K, Kameshima T, Joti Y, Katayama T, Togashi T, Yabashi M, Matsuda K, Bostedt C, Ueda K & Nagaya K, Proceedings of the National Academy of Sciences. Vol. 118(51), pp. e2111747118., (2021).
Abstract: Understanding the atomic-scale mechanism of crystallization is a fundamental issue in statistical mechanics and the basis for the synthesis of novel materials. We investigated the structures of single xenon nanoparticles at the early stage of formation by exploiting the femtosecond single-shot X-ray diffraction approach. We found the coexistence of a highly stacking-disordered structure and a stable face-centered cubic structure in the same single nanoparticles, suggesting that crystallization proceeds via an intermediate stacking-disordered phase. The results shine light on the early stages of condensed matter nucleation and demonstrate the effectiveness of the single-shot diffraction method for elucidating fast structural dynamics in atomic aggregates, feeding unique experimental information to nucleation and growth theory as well as to research and applications.Crystallization is a fundamental natural phenomenon and the ubiquitous physical process in materials science for the design of new materials. So far, experimental observations of the structural dynamics in crystallization have been mostly restricted to slow dynamics. We present here an exclusive way to explore the dynamics of crystallization in highly controlled conditions (i.e., in the absence of impurities acting as seeds of the crystallites) as it occurs in vacuum. We have measured the early formation stage of solid Xe nanoparticles nucleated in an expanding supercooled Xe jet by means of an X-ray diffraction experiment with 10-fs X-ray free-electron laser (XFEL) pulses. We found that the structure of Xe nanoparticles is not pure face-centered cubic (fcc), the expected stable phase, but a mixture of fcc and randomly stacked hexagonal close-packed (rhcp) structures. Furthermore, we identified the instantaneous coexistence of the comparably sized fcc and rhcp domains in single Xe nanoparticles. The observations are explained by the scenario of structural aging, in which the nanoparticles initially crystallize in the highly stacking-disordered rhcp phase and the structure later forms the stable fcc phase. The results are reminiscent of analogous observations in hard-sphere systems, indicating the universal role of the stacking-disordered phase in nucleation.The X-ray diffraction image data and the code used for the simulation are available in Zenodo (https://doi.org/10.5281/zenodo.5581210) (45).
BibTeX:
@article{Niozu2021,
  author = {Niozu, Akinobu and Kumagai, Yoshiaki and Hiraki, Toshiyuki Nishiyama and Fukuzawa, Hironobu and Motomura, Koji and Bucher, Maximilian and Asa, Kazuki and Sato, Yuhiro and Ito, Yuta and You, Daehyun and Ono, Taishi and Li, Yiwen and Kukk, Edwin and Miron, Catalin and Neagu, Liviu and Callegari, Carlo and Di Fraia, Michele and Rossi, Giorgio and Galli, Davide Emilio and Pincelli, Tommaso and Colombo, Alessandro and Owada, Shigeki and Tono, Kensuke and Kameshima, Takashi and Joti, Yasumasa and Katayama, Tetsuo and Togashi, Tadashi and Yabashi, Makina and Matsuda, Kazuhiro and Bostedt, Christoph and Ueda, Kiyoshi and Nagaya, Kiyonobu},
  title = {Crystallization kinetics of atomic crystals revealed by a single-shot and single-particle X-ray diffraction experiment},
  journal = {Proceedings of the National Academy of Sciences},
  year = {2021},
  volume = {118},
  number = {51},
  pages = {e2111747118},
  url = {https://www.pnas.org/content/pnas/118/51/e2111747118.full.pdf},
  doi = {10.1073/pnas.2111747118}
}
"Selective dissociation of the spectator Auger final states in O2 molecules"
Tian L, Ding B, Nicolas C, Wu R, Feng Y, Patanen M, Nandi S, Bozek J, Miron C & Liu X-J, Physical Review A., Apr, 2021. Vol. 103, pp. 043103. American Physical Society, (2021).
Abstract: Molecular cationic states with two valence holes and one n-Rydberg electron can be created after spectator Auger decay. Unraveling these states' dissociation is often very challenging due to the frequent occurrence of conical intersections between cationic potential energy curves. Here, based on an advanced analysis of the experimental multicoincidence data obtained after O1s core excitation in O2, we achieved an energy-resolution better than we recently exploited in Phys. Rev. A 99, 022511 (2019). We therefore revealed a group of weak channels in the two-dimensional energy-correlation map between the coincident resonant Auger electron and ion in addition to the previously reported strong ones. The fragments in the identified weak channels contain only outmost electrons in valence orbitals; in contrast, the fragments in the strong channels contain an outmost electron in a n'-Rydberg orbital. Compared with the strong channels, the weak channels preferentially occur at smaller principal quantum number n. It indicates that the electron orbital size tends to be conserved during the dissociation process. These weak features are suggested to be created by the Rydberg-valence mixing between the molecular spectator Auger final state and the very dissociative molecular cationic states without the Rydberg electron. A tendency to orbital selection is also suggested in the Rydberg-valence mixing..
BibTeX:
@article{PhysRevA.103.043103,
  author = {Tian, Lifang and Ding, Bocheng and Nicolas, Christophe and Wu, Ruichang and Feng, Yunfei and Patanen, Minna and Nandi, Saikat and Bozek, John and Miron, Catalin and Liu, Xiao-Jing},
  title = {Selective dissociation of the spectator Auger final states in O_2 molecules},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2021},
  volume = {103},
  pages = {043103},
  url = {https://link.aps.org/doi/10.1103/PhysRevA.103.043103},
  doi = {10.1103/PhysRevA.103.043103}
}
"Suppression of thermal nanoplasma emission in clusters strongly ionized by hard x-rays"
Kumagai Y, Jurek Z, Xu W, Saxena V, Fukuzawa H, Motomura K, Iablonskyi D, Nagaya K, Wada S-i, Ito Y, Takanashi T, Yamada S, Sakakibara Y, Hiraki TN, Umemoto T, Patanen M, Bozek JD, Dancus I, Cernaianu M, Miron C, Bauer T, Mucke M, Kukk E, Owada S, Togashi T, Tono K, Yabashi M, Son S-K, Ziaja B, Santra R & Ueda K , Journal of Physics B: Atomic, Molecular and Optical Physics., feb, 2021. Vol. 54(4), pp. 044001. IOP Publishing, (2021).
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.
BibTeX:
@article{Kumagai2021,
  author = {Yoshiaki Kumagai and Zoltan Jurek and Weiqing Xu and Vikrant Saxena and Hironobu Fukuzawa and Koji Motomura and Denys Iablonskyi and Kiyonobu Nagaya and Shin-ichi Wada and Yuta Ito and Tsukasa Takanashi and Shuhei Yamada and Yuta Sakakibara and Toshiyuki Nishiyama Hiraki and Takayuki Umemoto and Minna Patanen and John D Bozek and Ioan Dancus and Mihail Cernaianu and Catalin Miron and Tobias Bauer and Melanie Mucke and Edwin Kukk and Shigeki Owada and Tadashi Togashi and Kensuke Tono and Makina Yabashi and Sang-Kil Son and Beata Ziaja and Robin Santra and Kiyoshi Ueda},
  title = {Suppression of thermal nanoplasma emission in clusters strongly ionized by hard x-rays},
  journal = {Journal of Physics B: Atomic, Molecular and Optical Physics},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {54},
  number = {4},
  pages = {044001},
  url = {https://doi.org/10.1088/1361-6455/abd878},
  doi = {10.1088/1361-6455/abd878}
}
2020
"Characterizing crystalline defects in single nanoparticles from angular correlations of single-shot diffracted X-rays"
Niozu A, Kumagai Y, Nishiyama T, Fukuzawa H, Motomura K, Bucher M, Asa K, Sato Y, Ito Y, Takanashi T, You D, Ono T, Li Y, Kukk E, Miron C, Neagu L, Callegari C, Di Fraia M, Rossi G, Galli DE, Pincelli T, Colombo A, Owada S, Tono K, Kameshima T, Joti Y, Katayama T, Togashi T, Yabashi M, Matsuda K, Nagaya K, Bostedt C & Ueda K, IUCrJ. Vol. 7(2), pp. 276-286, (2020).
Abstract: Characterizing and controlling the uniformity of nanoparticles is crucial for their application in science and technology because crystalline defects in the nanoparticles strongly affect their unique properties. Recently, ultra-short and ultra-bright X-ray pulses provided by X-ray free-electron lasers (XFELs) opened up the possibility of structure determination of nanometre-scale matter with A spatial resolution. However, it is often difficult to reconstruct the 3D structural information from single-shot X-ray diffraction patterns owing to the random orientation of the particles. This report proposes an analysis approach for characterizing defects in nanoparticles using wide-angle X-ray scattering (WAXS) data from free-flying single nanoparticles. The analysis method is based on the concept of correlated X-ray scattering, in which correlations of scattered X-ray are used to recover detailed structural information. WAXS experiments of xenon nanoparticles, or clusters, were conducted at an XFEL facility in Japan by using the SPring-8 Ångstrom compact free-electron laser (SACLA). Bragg spots in the recorded single-shot X-ray diffraction patterns showed clear angular correlations, which offered significant structural information on the nanoparticles. The experimental angular correlations were reproduced by numerical simulation in which kinematical theory of diffraction was combined with geometric calculations. We also explain the diffuse scattering intensity as being due to the stacking faults in the xenon clusters.
BibTeX:
@article{Niozu2020,
  author = {Niozu, Akinobu and Kumagai, Yoshiaki and Nishiyama, Toshiyuki and Fukuzawa, Hironobu and Motomura, Koji and Bucher, Maximilian and Asa, Kazuki and Sato, Yuhiro and Ito, Yuta and Takanashi, Tsukasa and You, Daehyun and Ono, Taishi and Li, Yiwen and Kukk, Edwin and Miron, Catalin and Neagu, Liviu and Callegari, Carlo and Di Fraia, Michele and Rossi, Giorgio and Galli, Davide E. and Pincelli, Tommaso and Colombo, Alessandro and Owada, Shigeki and Tono, Kensuke and Kameshima, Takashi and Joti, Yasumasa and Katayama, Tetsuo and Togashi, Tadashi and Yabashi, Makina and Matsuda, Kazuhiro and Nagaya, Kiyonobu and Bostedt, Christoph and Ueda, Kiyoshi},
  title = {Characterizing crystalline defects in single nanoparticles from angular correlations of single-shot diffracted X-rays},
  journal = {IUCrJ},
  year = {2020},
  volume = {7},
  number = {2},
  pages = {276--286},
  url = {https://doi.org/10.1107/S205225252000144X},
  doi = {10.1107/S205225252000144X}
}
"Real-time observation of disintegration processes within argon clusters ionized by a hard-x-ray pulse of moderate fluence"
Kumagai Y, Jurek Z, Xu W, Fukuzawa H, Motomura K, Iablonskyi D, Nagaya K, Wada S-i, 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 S-K, Ziaja B, Santra R & Ueda K, Physical Review A., Feb, 2020. Vol. 101, pp. 023412. American Physical Society, (2020).
Abstract: We present a time-resolved study of disintegration within atomic clusters ionized by a hard-x-ray pulse of moderate fluence. It was performed with electron and ion spectroscopy, and complemented by theoretical simulations. The expanding clusters were probed with a near-infrared (NIR) laser pulse over a range of pump-probe delays from -4 to 10 ps. In addition to an increasing number of singly charged atomic ions, originating from the ionization of Rydberg atoms formed through electron-ion recombination, we observe a decrease of oligomer yields. The latter is due to the interaction of oligomers with the NIR probe pulse, leading to their dissociation. At time delays between -1 and 2 ps, efficient absorption of the NIR laser energy occurs, even though the NIR intensity is too low to trigger tuneling ionization of Ar atoms. Our observations are similar to earlier observations of the fragmentation behavior of clusters excited by soft-x-ray pulses. This indicates that the relaxation dynamics of x-ray-excited nano-objects are universal over a wide range of excitation photon energies.
BibTeX:
@article{PhysRevA.101.023412,
  author = {Kumagai, Yoshiaki and Jurek, Zoltan and Xu, Weiqing and Fukuzawa, Hironobu and Motomura, Koji and Iablonskyi, Denys and Nagaya, Kiyonobu and Wada, Shin-ichi and Mondal, Subhendu and Tachibana, Tetsuya and Ito, Yuta and Sakai, Tsukasa and Matsunami, Kenji and Nishiyama, Toshiyuki and Umemoto, Takayuki and Nicolas, Christophe and Miron, Catalin and Togashi, Tadashi and Ogawa, Kanade and Owada, Shigeki and Tono, Kensuke and Yabashi, Makina and Son, Sang-Kil and Ziaja, Beata and Santra, Robin and Ueda, Kiyoshi},
  title = {Real-time observation of disintegration processes within argon clusters ionized by a hard-x-ray pulse of moderate fluence},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2020},
  volume = {101},
  pages = {023412},
  url = {https://link.aps.org/doi/10.1103/PhysRevA.101.023412},
  doi = {10.1103/PhysRevA.101.023412}
}
"Refinement for single-nanoparticle structure determination from low-quality single-shot coherent diffraction data"
Nishiyama T, Niozu A, Bostedt C, Ferguson KR, Sato Y, Hutchison C, Nagaya K, Fukuzawa H, Motomura K, Wada S-i, Sakai T, Matsunami K, Matsuda K, Tachibana T, Ito Y, Xu W, Mondal S, Umemoto T, Nicolas C, Miron C, Kameshima T, Joti Y, Tono K, Hatsui T, Yabashi M & Ueda K , IUCrJ. Vol. 7(1), pp. 10-17, (2020).
Abstract: With the emergence of X-ray free-electron lasers, it is possible to investigate the structure of nanoscale samples by employing coherent diffractive imaging in the X-ray spectral regime. In this work, we developed a refinement method for structure reconstruction applicable to low-quality coherent diffraction data. The method is based on the gradient search method and considers the missing region of a diffraction pattern and the small number of detected photons. We introduced an initial estimate of the structure in the method to improve the convergence. The present method is applied to an experimental diffraction pattern of an Xe cluster obtained in an X-ray scattering experiment at the SPring-8 Angstrom Compact free-electron LAser (SACLA) facility. It is found that the electron density is successfully reconstructed from the diffraction pattern with a large missing region, with a good initial estimate of the structure. The diffraction pattern calculated from the reconstructed electron density reproduced the observed diffraction pattern well, including the characteristic intensity modulation in each ring. Our refinement method enables structure reconstruction from diffraction patterns under difficulties such as missing areas and low diffraction intensity, and it is potentially applicable to the structure determination of samples that have low scattering power.
BibTeX:
@article{Nishiyama2020,
  author = {Nishiyama, Toshiyuki and Niozu, Akinobu and Bostedt, Christoph and Ferguson, Ken R. and Sato, Yuhiro and Hutchison, Christopher and Nagaya, Kiyonobu and Fukuzawa, Hironobu and Motomura, Koji and Wada, Shin-ichi and Sakai, Tsukasa and Matsunami, Kenji and Matsuda, Kazuhiro and Tachibana, Tetsuya and Ito, Yuta and Xu, Weiqing and Mondal, Subhendu and Umemoto, Takayuki and Nicolas, Christophe and Miron, Catalin and Kameshima, Takashi and Joti, Yasumasa and Tono, Kensuke and Hatsui, Takaki and Yabashi, Makina and Ueda, Kiyoshi},
  title = {Refinement for single-nanoparticle structure determination from low-quality single-shot coherent diffraction data},
  journal = {IUCrJ},
  year = {2020},
  volume = {7},
  number = {1},
  pages = {10--17},
  url = {https://doi.org/10.1107/S2052252519014222},
  doi = {10.1107/S2052252519014222}
}
2019
"Resonant x-ray second-harmonic generation in atomic gases"
Liu J-C, Miron C, Ågren H, Polyutov S & Gel'mukhanov F, Physical Review A., Dec, 2019. Vol. 100, pp. 063403. American Physical Society, (2019).
Abstract: We explore the x-ray second-harmonic generation process induced by resonant two-photon absorption in systems with inversion symmetry. We show that this process becomes allowed in the x-ray region due to nondipole contributions. It is found that, although a plane-wave pump field generates only a longitudinal second-harmonic field, a Gaussian pump beam creates also a radially polarized transverse second-harmonic field which is stronger than the longitudinal one. Contrary to the longitudinal component, the transverse second-harmonic field with zero intensity on the axis of the pump beam can run in free space. Our theory is applied to Ar and Ne atomic vapors and predicts an energy conversion efficiency of x-ray second-harmonic generation of 3.2*10-11 and 1.3*10-12, respectively.
BibTeX:
@article{PhysRevA.100.063403,
  author = {Liu, Ji-Cai and Miron, Catalin and Ågren, Hans and Polyutov, Sergey and Gel'mukhanov, Faris},
  title = {Resonant x-ray second-harmonic generation in atomic gases},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2019},
  volume = {100},
  pages = {063403},
  url = {https://link.aps.org/doi/10.1103/PhysRevA.100.063403},
  doi = {10.1103/PhysRevA.100.063403}
}
"Multispectroscopic Study of Single Xe Clusters Using XFEL Pulses"
Nishiyama T, Bostedt C, Ferguson KR, Hutchison C, Nagaya K, Fukuzawa H, Motomura K, Wada S-i, Sakai T, Matsunami K, Matsuda K, Tachibana T, Ito Y, Xu W, Mondal S, Umemoto T, Miron C, Nicolas C, Kameshima T, Joti Y, Tono K, Hatsui T, Yabashi M & Ueda K, Applied Sciences, Vol. 9(22), pp. 4932, (2019).
Abstract: X-ray free-electron lasers (XFELs) deliver ultrashort coherent laser pulses in the X-ray spectral regime, enabling novel investigations into the structure of individual nanoscale samples. In this work, we demonstrate how single-shot small-angle X-ray scattering (SAXS) measurements combined with fluorescence and ion time-of-flight (TOF) spectroscopy can be used to obtain size- and structure-selective evaluation of the light-matter interaction processes on the nanoscale. We recorded the SAXS images of single xenon clusters using XFEL pulses provided by the SPring-8 Angstrom compact free-electron laser (SACLA). The XFEL fluences and the radii of the clusters at the reaction point were evaluated and the ion TOF spectra and fluorescence spectra were sorted accordingly. We found that the XFEL fluence and cluster size extracted from the diffraction patterns showed a clear correlation with the fluorescence and ion TOF spectra. Our results demonstrate the effectiveness of the multispectroscopic approach for exploring laser-matter interaction in the X-ray regime without the influence of the size distribution of samples and the fluence distribution of the incident XFEL pulses.
BibTeX:
@article{Nishiyama2019,
  author = {Nishiyama, Toshiyuki and Bostedt, Christoph and Ferguson, Ken R. and Hutchison, Christopher and Nagaya, Kiyonobu and Fukuzawa, Hironobu and Motomura, Koji and Wada, Shin-ichi and Sakai, Tsukasa and Matsunami, Kenji and Matsuda, Kazuhiro and Tachibana, Tetsuya and Ito, Yuta and Xu, Weiqing and Mondal, Subhendu and Umemoto, Takayuki and Miron, Catalin and Nicolas, Christophe and Kameshima, Takashi and Joti, Yasumasa and Tono, Kensuke and Hatsui, Takaki and Yabashi, Makina and Ueda, Kiyoshi},
  title = {Multispectroscopic Study of Single Xe Clusters Using XFEL Pulses},
  journal = {Applied Sciences
}, year = {2019}, volume = {9}, number = {22}, pages = {4932
}, url = {https://www.mdpi.com/2076-3417/9/22/4932}, doi = {10.3390/app9224932} }
"Ultrafast Structural Dynamics of Nanoparticles in Intense Laser Fields"
Nishiyama T, Kumagai Y, Niozu A, Fukuzawa H, Motomura K, Bucher M, Ito Y, Takanashi T, Asa K, Sato Y, You D, Li Y, Ono T, Kukk E, Miron C, Neagu L, Callegari C, Di Fraia M, Rossi G, Galli DE, Pincelli T, Colombo A, Kameshima T, Joti Y, Hatsui T, Owada S, Katayama T, Togashi T, Tono K, Yabashi M, Matsuda K, Bostedt C, Nagaya K and Ueda K, Physical Review Letters., Sep, 2019. Vol. 123, pp. 123201. American Physical Society, (2019).
Abstract: Femtosecond laser pulses have opened new frontiers for the study of ultrafast phase transitions and nonequilibrium states of matter. In this Letter, we report on structural dynamics in atomic clusters pumped with intense near-infrared (NIR) pulses into a nanoplasma state. Employing wide-angle scattering with intense femtosecond x-ray pulses from a free-electron laser source, we find that highly excited xenon nanoparticles retain their crystalline bulk structure and density in the inner core long after the driving NIR pulse. The observed emergence of structural disorder in the nanoplasma is consistent with a propagation from the surface to the inner core of the clusters.
BibTeX:
@article{PhysRevLett.123.123201,
  author = {Nishiyama, Toshiyuki and Kumagai, Yoshiaki and Niozu, Akinobu and Fukuzawa, Hironobu and Motomura, Koji and Bucher, Maximilian and Ito, Yuta and Takanashi, Tsukasa and Asa, Kazuki and Sato, Yuhiro and You, Daehyun and Li, Yiwen and Ono, Taishi and Kukk, Edwin and Miron, Catalin and Neagu, Liviu and Callegari, Carlo and Di Fraia, Michele and Rossi, Giorgio and Galli, Davide E. and Pincelli, Tommaso and Colombo, Alessandro and Kameshima, Takashi and Joti, Yasumasa and Hatsui, Takaki and Owada, Shigeki and Katayama, Tetsuo and Togashi, Tadashi and Tono, Kensuke and Yabashi, Makina and Matsuda, Kazuhiro and Bostedt, Christoph and Nagaya, Kiyonobu and Ueda, Kiyoshi},
  title = {Ultrafast Structural Dynamics of Nanoparticles in Intense Laser Fields},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2019},
  volume = {123},
  pages = {123201},
  url = {https://link.aps.org/doi/10.1103/PhysRevLett.123.123201},
  doi = {10.1103/PhysRevLett.123.123201}
}
"Real-time observation of X-ray-induced intramolecular and interatomic electronic decay in CH2I2"
Fukuzawa H, Takanashi T, Kukk E, Motomura K, Wada S-i, 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 X-J, 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, Nature Communications., Vol. 10(1), pp. 2186, (2019).
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.
BibTeX:
@article{Fukuzawa2019,
  author = {Fukuzawa, Hironobu and Takanashi, Tsukasa and Kukk, Edwin and Motomura, Koji and Wada, Shin-ichi and Nagaya, Kiyonobu and Ito, Yuta and Nishiyama, Toshiyuki and Nicolas, Christophe and Kumagai, Yoshiaki and Iablonskyi, Denys and Mondal, Subhendu and Tachibana, Tetsuya and You, Daehyun and Yamada, Syuhei and Sakakibara, Yuta and Asa, Kazuki and Sato, Yuhiro and Sakai, Tsukasa and Matsunami, Kenji and Umemoto, Takayuki and Kariyazono, Kango and Kajimoto, Shinji and Sotome, Hikaru and Johnsson, Per and Schöffler, Markus S. and Kastirke, Gregor and Kooser, Kuno and Liu, Xiao-Jing and Asavei, Theodor and Neagu, Liviu and Molodtsov, Serguei and Ochiai, Kohei and Kanno, Manabu and Yamazaki, Kaoru and Owada, Shigeki and Ogawa, Kanade and Katayama, Tetsuo and Togashi, Tadashi and Tono, Kensuke and Yabashi, Makina and Ghosh, Aryya and Gokhberg, Kirill and Cederbaum, Lorenz S. and Kuleff, Alexander I. and Fukumura, Hiroshi and Kishimoto, Naoki and Rudenko, Artem and Miron, Catalin and Kono, Hirohiko and Ueda, Kiyoshi},
  title = {Real-time observation of X-ray-induced intramolecular and interatomic electronic decay in CH2I2},
  journal = {Nature Communications},
  year = {2019},
  volume = {10},
  number = {1},
  pages = {2186},
  url = {https://doi.org/10.1038/s41467-019-10060-z},
  doi = {10.1038/s41467-019-10060-z}
}
"Identification of Coupling Mechanisms between Ultraintense Laser Light and Dense Plasmas"
Chopineau L, Leblanc A, Blaclard G, Denoeud A, Thévenet M, Vay J-L, Bonnaud G, Martin P, Vincenti H et Quéré F, Physical Review X., Mar, 2019. Vol. 9, pp. 011050. American Physical Society, (2019).
Abstract: The interaction of intense laser beams with plasmas created on solid targets involves a rich nonlinear physics. Because such dense plasmas are reflective for laser light, the coupling with the incident beam occurs within a thin layer at the interface between plasma and vacuum. One of the main paradigms used to understand this coupling, known as the Brunel mechanism, is expected to be valid only for very steep plasma surfaces. Despite innumerable studies, its validity range remains uncertain, and the physics involved for smoother plasma-vacuum interfaces is unclear, especially for ultrahigh laser intensities. We report the first comprehensive experimental and numerical study of the laser-plasma coupling mechanisms as a function of the plasma interface steepness, in the relativistic interaction regime. Our results reveal a clear transition from the temporally periodic Brunel mechanism to a chaotic dynamic associated to stochastic heating. By revealing the key signatures of these two distinct regimes on experimental observables, we provide an important landmark for the interpretation of future experiments.
BibTeX:
@article{PhysRevX.9.011050,
  author = {Chopineau, L. and Leblanc, A. and Blaclard, G. and Denoeud, A. and Thévenet, M. and Vay, J-L. and Bonnaud, G. and Martin, Ph. and Vincenti, H. and Quéré, F.},
  title = {Identification of Coupling Mechanisms between Ultraintense Laser Light and Dense Plasmas},
  journal = {Phys. Rev. X},
  publisher = {American Physical Society},
  year = {2019},
  volume = {9},
  pages = {011050},
  url = {https://link.aps.org/doi/10.1103/PhysRevX.9.011050},
  doi = {10.1103/PhysRevX.9.011050}
}
"Sequential electron emission and nuclear dissociation after the O 1s → (4Σ-u )4pσ excitation in O2 molecules"
Song S, Ding B, Xu W, Nicolas C, Patanen M, Nandi S, Bozek J, Miron C, Xiao Z et Liu X-J, Physical Review A., Feb, 2019. Vol. 99, pp. 022511. American Physical Society, (2019).
Abstract: When an electron is resonantly excited from a core orbital to a Rydberg one in a molecule, complex multitime-scale multistep processes are triggered. By using a high-resolution energy-resolved coincidence between Auger electron and ions, we identified the sequences of processes following the spectator Auger decays induced by K-shell excitation in O2. The first step of the spectator Auger decay can end up to a few metastable O2+ states which autoionize into stable O22+. However, the majority of O2+ states are dissociative. They evolve into several dissociation limits with complex crossings between potential-energy curves. After the molecular dissociation is finished, the generated fragments can further decay either by fluorescence emission or by autoionization. Interestingly, some electrons are always emitted after molecular dissociation..
BibTeX:
@article{PhysRevA.99.022511,
  author = {Song, Shan and Ding, Bocheng and Xu, Weiqing and Nicolas, Christophe and Patanen, Minna and Nandi, Saikat and Bozek, John and Miron, Catalin and Xiao, Zhisong and Liu, Xiao-Jing},
  title = {Sequential electron emission and nuclear dissociation after the O 1s → (4Σ-u )4pσ excitation in O2 molecules},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2019},
  volume = {99},
  pages = {022511},
  url = {https://link.aps.org/doi/10.1103/PhysRevA.99.022511},
  doi = {10.1103/PhysRevA.99.022511}
}
"Coulomb implosion of tetrabromothiophene observed under multiphoton ionization by free-electron-laser soft-x-ray pulses"
Kukk E, Myllynen H, Nagaya K, Wada S, Bozek JD, Takanashi T, You D, Niozu A, Kooser K, Gaumnitz T, Pelimanni E, Berholts M, Granroth S, Yokono N, Fukuzawa H, Miron C and Ueda K, Physical Review A., Feb, 2019. Vol. 99, pp. 023411. American Physical Society, 2019.
Abstract: Soft-x-ray free-electron-laser pulses were used to create highly charged molecular tetrabromothiophene species by sequential multiphoton ionization from bromine 3d orbitals. The experiment was performed at the SACLA facility in Japan and the products of molecular dissociation were analyzed by means of multicoincidence momentum-resolved ion time-of-flight spectroscopy. Total charge states up to +13 atomic units were produced, creating a particular dissociation pattern for the carbon ions, a Coulomb implosion, due to the concerted forces by the surrounding heavy bromine ions. This behavior was explored both experimentally and by numerical molecular-dynamics simulations and the fingerprints of the Coulomb implosion were identified in both. In simulations, Coulomb implosion was predicted to be highly sensitive to the initial (thermal) motion of the atoms and, after including vibrational motion for several temperatures, good general agreement between the experiment and simulations was found. The agreement with the experiment was further improved by adding charge dynamics to the simulation, according to our point-charge dynamics model with empirical rate constants.
BibTeX:
@article{PhysRevA.99.023411,
  author = {Kukk, E. and Myllynen, H. and Nagaya, K. and Wada, S. and Bozek, J. D. and Takanashi, T. and You, D. and Niozu, A. and Kooser, K. and Gaumnitz, T. and Pelimanni, E. and Berholts, M. and Granroth, S. and Yokono, N. and Fukuzawa, H. and Miron, C. and Ueda, K.},
  title = {Coulomb implosion of tetrabromothiophene observed under multiphoton ionization by free-electron-laser soft-x-ray pulses},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2019},
  volume = {99},
  pages = {023411},
  url = {https://link.aps.org/doi/10.1103/PhysRevA.99.023411},
  doi = {10.1103/PhysRevA.99.023411}
}
2018
"Photoionization dynamics of cis-dichloroethene from investigation of vibrationally resolved photoelectron spectra and angular distributions"
Powis I, Menzies RC, Holland DMP, Trofimov AB, Skitnevskaya AD, Gromov EV, Antonsson E, Patanen M, Nicolas C and Miron C, The Journal of Chemical Physics. Vol. 149(7), pp. 074305, (2018).
Abstract: The influence of vibronic coupling on the outer valence ionic states of cis-dichloroethene has been investigated by recording photoelectron spectra over the excitation range 19–90 eV using plane polarized synchrotron radiation, for two polarization orientations. The photoelectron anisotropy parameters and electronic state branching ratios derived from these spectra have been compared to theoretical predictions obtained with the continuum multiple scattering approach. This comparison shows that the photoionization dynamics of the à p2B2sub>, B 2A1, C̃ 2A2, and D̃ 2B1 states, all of which are formed through the ejection of an electron from a nominally chlorine lone-pair orbital, exhibit distinct evidence of the Cooper minimum associated with the halogen atom. While retaining a high degree of atomic character, these orbital ionizations nevertheless display clear distinctions. Simulations, assuming the validity of the Born-Oppenheimer and the Franck-Condon approximations, of the X̃ 2B1, à 2B2, and D̃2B1 state photoelectron bands have allowed some of the vibrational structure observed in the experimental spectra to be assigned. The simulations provide a very satisfactory interpretation for the X̃ 2B1 state band but appear less successful for the Ã2B2 and D̃ 2B1 states, with irregularities appearing in both. The B̃ 2A1 and C̃ 2A2 state photoelectron bands exhibit very diffuse and erratic profiles that cannot be reproduced at this level. Photoelectron anisotropy parameters, β, have been evaluated as a function of binding energy across the studied photon energy range. There is a clear step change in the β values of the à 2B2 band at the onset of the perturbed peak intensities, with β evidently adopting the value of the B̃2A1 band β. The D̃ 2B1 band β values also display an unexpected vibrational level dependence, contradicting Franck-Condon expectations. These various behaviors are inferred to be a consequence of vibronic coupling in this system.
BibTeX:
@article{Powis2018,
  author = {Powis, I. and Menzies, R. C. and Holland, D. M. P. and Trofimov, A. B. and Skitnevskaya, A. D. and Gromov, E. V. and Antonsson, E. and Patanen, M. and Nicolas, C. and Miron, C.},
  title = {Photoionization dynamics of cis-dichloroethene from investigation of vibrationally resolved photoelectron spectra and angular distributions},
  journal = {The Journal of Chemical Physics},
  year = {2018},
  volume = {149},
  number = {7},
  pages = {074305},
  url = {https://aip.scitation.org/doi/abs/10.1063/1.5042216},
  doi = {10.1063/1.5042216}
}
"An experimental and theoretical study of the photoelectron spectra of cis-dichloroethene: Valence shell vertical ionization and vibronic coupling in the low-lying cationic states"
Trofimov AB, Powis I, Menzies RC, Holland DMP, Antonsson E, Patanen M, Nicolas C, Miron C, Skitnevskaya AD, Gromov EV and Köppel H, The Journal of Chemical Physics., August, 2018. Vol. 149(7), pp. 074306. American Institute of Physics, (2018).
Abstract: The valence shell photoelectron spectrum of cis-dichloroethene has been studied both experimentally and theoretically. Photoelectron spectra have been recorded with horizontally and vertically plane polarized synchrotron radiation, thereby allowing the anisotropy parameters, characterizing the angular distributions, to be determined. The third-order algebraic-diagrammatic construction approximation scheme for the one-particle Green’s function has been employed to compute the complete valence shell ionization spectrum. In addition, the vertical ionization energies have been calculated using the outer valence Green’s function (OVGF) method and the equation-of-motion coupled-cluster, with single and double substitutions for calculating ionization potentials (EOM-IP-CCSD) model. The theoretical results have enabled assignments to be proposed for most of the structure observed in the experimental spectra, including the inner-valence regions dominated by satellite states. The linear vibronic coupling model has been employed to study the vibrational structure of the lowest photoelectron bands, using parameters obtained from ab initiocalculations. The ground state optimized geometries and vibrational frequencies have been computed at the level of the second-order Møller-Plesset perturbation theory, and the dependence of the ionization energies on the nuclear configuration has been evaluated using the OVGF method. While the adiabatic approximation holds for the  2B1 state photoelectron band, the   2B2  2A1, and   2A2 states interact vibronically and form a complex photoelectron band system with four distinct maxima. The   2B1 and  2B2 states also interact vibronically with each other. The potential energy surface of the  2B1 state is predicted to have a double-minimum shape with respect to the out-of-plane a2 deformations of the molecular structure. The single photoelectron band resulting from this interaction is characterized by a highly irregular structure, reflecting the non-adiabatic nuclear dynamics occurring on the two coupled potential energy surfaces forming a conical intersection close to the minimum of the  2B2 state.
BibTeX:
@article{Trofimov2018,
  author = {Trofimov, A. B. and Powis, I. and Menzies, R. C. and Holland, D. M. P. and Antonsson, E. and Patanen, M. and Nicolas, C. and Miron, C. and Skitnevskaya, A. D. and Gromov, E. V. and Köppel, H.},
  title = {An experimental and theoretical study of the photoelectron spectra of cis-dichloroethene: Valence shell vertical ionization and vibronic coupling in the low-lying cationic states},
  journal = {The Journal of Chemical Physics},
  publisher = {American Institute of Physics},
  year = {2018},
  volume = {149},
  number = {7},
  pages = {074306},
  url = {https://doi.org/10.1063/1.5033425},
  doi = {10.1063/1.5033425}
}
"Following the Birth of a Nanoplasma Produced by an Ultrashort Hard-X-Ray Laser in Xenon Clusters"
Kumagai Y, Fukuzawa H, Motomura K, Iablonskyi D, Nagaya K, Wada S-i, Ito Y, Takanashi T, Sakakibara Y, You D, Nishiyama T, Asa K, Sato Y, Umemoto T, Kariyazono K, Kukk E, Kooser K, Nicolas C, Miron C, Asavei T, Neagu L, Schöffler MS, Kastirke G, Liu X-j, Owada S, Katayama T, Togashi T, Tono K, Yabashi M, Golubev NV, Gokhberg K, Cederbaum LS, Kuleff AI and Ueda K, Physical Review X., Aug, 2018. Vol. 8, pp. 031034. American Physical Society, (2018).
Abstract: X-ray free-electron lasers (XFELs) made available a new regime of x-ray intensities, revolutionizing the ultrafast structure determination and laying the foundations of the novel field of nonlinear x-ray optics. Although earlier studies revealed nanoplasma formation when an XFEL pulse interacts with any nanometer-scale matter, the formation process itself has never been decrypted and its timescale was unknown. Here we show that time-resolved ion yield measurements combined with a near-infrared laser probe reveal a surprisingly ultrafast population (~ 12 fs), followed by a slower depopulation (~ 250 fs) of highly excited states of atomic fragments generated in the process of XFEL-induced nanoplasma formation. Inelastic scattering of Auger electrons and interatomic Coulombic decay are suggested as the mechanisms populating and depopulating, respectively, these excited states. The observed response occurs within the typical x-ray pulse durations and affects x-ray scattering, thus providing key information on the foundations of x-ray imaging with XFELs.
BibTeX:
@article{PhysRevX.8.031034,
  author = {Kumagai, Yoshiaki and Fukuzawa, Hironobu and Motomura, Koji and Iablonskyi, Denys and Nagaya, Kiyonobu and Wada, Shin-ichi and Ito, Yuta and Takanashi, Tsukasa and Sakakibara, Yuta and You, Daehyun and Nishiyama, Toshiyuki and Asa, Kazuki and Sato, Yuhiro and Umemoto, Takayuki and Kariyazono, Kango and Kukk, Edwin and Kooser, Kuno and Nicolas, Christophe and Miron, Catalin and Asavei, Theodor and Neagu, Liviu and Schöffler, Markus S. and Kastirke, Gregor and Liu, Xiao-jing and Owada, Shigeki and Katayama, Tetsuo and Togashi, Tadashi and Tono, Kensuke and Yabashi, Makina and Golubev, Nikolay V. and Gokhberg, Kirill and Cederbaum, Lorenz S. and Kuleff, Alexander I. and Ueda, Kiyoshi},
  title = {Following the Birth of a Nanoplasma Produced by an Ultrashort Hard-X-Ray Laser in Xenon Clusters},
  journal = {Phys. Rev. X},
  publisher = {American Physical Society},
  year = {2018},
  volume = {8},
  pages = {031034},
  url = {https://link.aps.org/doi/10.1103/PhysRevX.8.031034},
  doi = {10.1103/PhysRevX.8.031034}
}
"Radiation-Induced Chemical Dynamics in Ar Clusters Exposed to Strong X-Ray Pulses"
Kumagai Y, Jurek Z, Xu W, Fukuzawa H, Motomura K, Iablonskyi D, Nagaya K, Wada S-i, 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 S-K, Ziaja B, Santra R and Ueda K, Physical Review Letters., Vol. 120(22), pp. 223201. American Physical Society, (2018)
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.
BibTeX:
@article{Kumagai2018,
  author = {Kumagai, Yoshiaki and Jurek, Zoltan and Xu, Weiqing and Fukuzawa, Hironobu and Motomura, Koji and Iablonskyi, Denys and Nagaya, Kiyonobu and Wada, Shin-ichi and Mondal, Subhendu and Tachibana, Tetsuya and Ito, Yuta and Sakai, Tsukasa and Matsunami, Kenji and Nishiyama, Toshiyuki and Umemoto, Takayuki and Nicolas, Christophe and Miron, Catalin and Togashi, Tadashi and Ogawa, Kanade and Owada, Shigeki and Tono, Kensuke and Yabashi, Makina and Son, Sang-Kil and Ziaja, Beata and Santra, Robin and Ueda, Kiyoshi},
  title = {Radiation-Induced Chemical Dynamics in Ar Clusters Exposed to Strong X-Ray Pulses},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2018},
  volume = {120},
  number = {22},
  pages = {223201},
  url = {https://link.aps.org/doi/10.1103/PhysRevLett.120.223201},
  doi = {10.1103/PhysRevLett.120.223201}
}
"Synchrotron-Radiation-Based Soft X-ray Electron Spectroscopies Applied to Structural and Chemical Characterization of Isolated Species, from Molecules to Nano-objects"
Miron C, Patanen M and Benkoula S , In Synchrotron Radiation in Materials Science. , pp. 321-355. Wiley-VCH Verlag GmbH & Co. KGaA, (2018).
Abstract: With its extended tunability from the IR to hard X-rays and the exceptional spectral brightness offered by the third generation storage rings, synchrotron radiation (SR) has become an invaluable investigation tool. Major methodological developments have been recently undertaken, first applied to simple systems, isolated atoms and molecules - that can be often modeled ab initio - and then extended to the investigation of more and more complex species, up to the soft and hard condensed matter. Here, we present some of the most recent achievements in SR-based soft X-ray electron spectroscopy applied to the structural characterization of isolated species of increasing complexity from molecules to clusters and nanoparticles. Special attention is devoted to very high-resolution studies of free molecules revealing physical phenomena such as electron diffraction and interference effects, as well as detailed information about the potential energy surfaces. Beyond this, we will see how technical progress of SR-based soft X-ray spectroscopy opens new routes to structural studies on freestanding nanosystems. These achievements have only become possible using the new experimental opportunities offered by the most advanced SR facilities.
BibTeX:
@inbook{Miron2018a,
  author = {Miron, Catalin and Patanen, Minna and Benkoula, Safia},
  title = {Synchrotron-Radiation-Based Soft X-ray Electron Spectroscopies Applied to Structural and Chemical Characterization of Isolated Species, from Molecules to Nano-objects},
  booktitle = {Synchrotron Radiation in Materials Science},
  publisher = {Wiley-VCH Verlag GmbH & Co. KGaA},
  year = {2018},
  pages = {321--355},
  url = {http://dx.doi.org/10.1002/9783527697106.ch10},
  doi = {10.1002/9783527697106.ch10}
}
2017
"Electronic-state interference in the C1s excitation and decay of methyl chloride studied by angularly resolved Auger spectroscopy"
Nandi S, Nicolas C, Artemyev AN, Novikovskiy NM, Miron C, Bozek JD and Demekhin PV , Physical Review A., Nov, 2017. Vol. 96, pp. 052501. American Physical Society, (2017).
Abstract: Resonant Auger (RA) decay spectra of carbon 1s 1 s excited CH3Cl CH 3 Cl molecules are recorded with angular resolution using linearly polarized synchrotron radiation. The selected photon energies corresponding to the C 1s8a1 1 s 8 a 1 core to lowest unoccupied molecular orbital and C 1s4sa1 1 s 4 s a 1 , 4pe 4 p e , and 4pa1 4 p a 1 core to Rydberg excitations of methyl chloride are used and electrons in the binding energy range of 11–37 eV are detected. The vibrationally unresolved RA electron angular distributions, recorded for participator Auger transitions populating the X X , A A , B B , and C C states of the CH3Cl+ CH 3 Cl + ion, exhibit strong variations across the selected electronic resonances. These observations are interpreted with the help of ab initio electronic structure and dynamics calculations, which account for electronic-state interference between the direct and different resonant ionization pathways. For spectator transitions, the theory predicts almost isotropic angular distributions with moderate changes of β parameters around zero, which is in agreement with the experimental observations.
BibTeX:
@article{PhysRevA.96.052501,
  author = {Nandi, S. and Nicolas, C. and Artemyev, A. N. and Novikovskiy, N. M. and Miron, C. and Bozek, J. D. and Demekhin, Ph. V.},
  title = {Electronic-state interference in the C1s excitation and decay of methyl chloride studied by angularly resolved Auger spectroscopy},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2017},
  volume = {96},
  pages = {052501},
  url = {https://link.aps.org/doi/10.1103/PhysRevA.96.052501},
  doi = {10.1103/PhysRevA.96.052501}
}
"Plasma holograms for ultrahigh-intensity optics"
Leblanc A, Denoeud A, Chopineau L, Mennerat G, Martin P & Quere F, Nat Phys., January, 2017. Vol. advance online publication, pp. -. Nature Publishing Group. (2017).
Abstract: The manipulation of ultraintense laser beams gets increasingly challenging with growing laser peak power, as the breakdown of conventional optics imposes ever larger beam diameters. Using compact plasma-based optical elements to control or even generate such beams is a promising approach, since plasmas can sustain considerable light intensities. We introduce a new type of plasma optics, called plasma holograms, by initiating plasma expansion on a flat solid target with a holographic prepulse beam focus. A modulated plasma surface then grows out of the target after ionization, which can be used for several picoseconds to diffract and spatially shape ultraintense laser beams. On the basis of this concept, we demonstrate the generation of fork plasma gratings, which we use to induce optical vortices on a femtosecond laser beam as well as its high-order harmonics, at intensities exceeding 1019Wcm-2. These plasma holograms open up a whole new range of possibilities for the manipulation of ultraintense lasers and the generation of structured coherent short-wavelength sources.
BibTeX:
@article{leblanc2017,
  author = {Leblanc, A. and Denoeud, A. and Chopineau, L. and Mennerat, G. and Martin, Ph. and Quere, F.},
  title = {Plasma holograms for ultrahigh-intensity optics},
  journal = {Nat Phys},
  publisher = {Nature Publishing Group},
  year = {2017},
  volume = {advance online publication},
  pages = {--},
  url = {http://dx.doi.org/10.1038/nphys4007},
  doi = {10.1038/nphys4007}
}
2015
"Design and current progress of the Apollon 10 PW project"
Zou JP, Le Blanc C, Papadopoulos DN, Chériaux G, Georges P, Mennerat G, Druon F, Lecherbourg L, Pellegrina A, Ramirez P, Giambruno F, Fréneaux A, Leconte F, Badarau D, Boudenne JM, Fournet D, Valloton T, Paillard JL, Veray JL, Pina M, Monot P, Chambaret JP, Martin P, Mathieu F, Audebert P & Amiranoff F, High Power Laser Science and Engineering. Vol. 3, pp. e2. Cambridge University Press, (2015).
Abstract: The objective of the Apollon project is the generation of 10 PW peak power pulses of 15 fs at 1 shot/minute. In this paper the Apollon facility design, the technological challenges and the current progress of the project will be presented.
BibTeX:
@article{Zou2015,
  author = {Zou, J. P. and Le Blanc, C. and Papadopoulos, D. N. and Chériaux, G. and Georges, P. and Mennerat, G. and Druon, F. and Lecherbourg, L. and Pellegrina, A. and Ramirez, P. and Giambruno, F. and Fréneaux, A. and Leconte, F. and Badarau, D. and Boudenne, J. M. and Fournet, D. and Valloton, T. and Paillard, J. L. and Veray, J. L. and Pina, M. and Monot, P. and Chambaret, J. P. and Martin, P. and Mathieu, F. and Audebert, P. and Amiranoff, F.},
  title = {Design and current progress of the Apollon 10 PW project},
  journal = {High Power Laser Science and Engineering},
  publisher = {Cambridge University Press},
  year = {2015},
  volume = {3},
  pages = {e2},
  edition = {2015/01/23},
  url = {https://www.cambridge.org/core/article/design-and-current-progress-of-the-apollon-10-pw-project/1595DB33A434A0BE420BD042D7C2D725},
  doi = {10.1017/hpl.2014.41}
}
2014
"Optically Controlled Solid-Density Transient Plasma Gratings"
Monchocé S, Kahaly S, Leblanc A, Videau L, Combis P., Réau F, Garzella D, D'Oliveira P, Martin P & Quéré F, Phys. Rev. Lett., Vol. 112(14), pp. 145008-. American Physical Society. April, (2014).
Abstract: A general approach for optically controlled spatial structuring of overdense plasmas generated at the surface of initially plain solid targets is presented. We demonstrate it experimentally by creating sinusoidal plasma gratings of adjustable spatial periodicity and depth, and study the interaction of these transient structures with an ultraintense laser pulse to establish their usability at relativistically high intensities. We then show how these gratings can be used as a "spatial ruler" to determine the source size of the high-order harmonic beams produced at the surface of an overdense plasma. These results open new directions both for the metrology of laser-plasma interactions and the emerging field of ultrahigh intensity plasmonics.
BibTeX:
@article{Monchocé2014,
  author = {Monchocé, S. and Kahaly, S. and Leblanc, A. and Videau, L. and Combis,P., and Réau, F. and Garzella, D. and D'Oliveira, P. and Martin, Ph. and Quéré, F.},
  title = {Optically Controlled Solid-Density Transient Plasma Gratings},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2014},
  volume = {112},
  number = {14},
  pages = {145008--},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.112.145008},
  doi = {10.1103/PhysRevLett.112.145008}
}
"Energetic ions at moderate laser intensities using foam-based multi-layered targets"
Passoni M, Zani A, Sgattoni A, Dellasega D, Macchi A, Prencipe I, Floquet V, Martin P, Liseykina TV & Ceccotti T, Plasma Physics and Controlled Fusion. Vol. 56(4), pp. 045001 - (2014).
Abstract: The experimental feasibility of the laser-driven ion acceleration concept with multi-layered, foam-based targets has been investigated. Targets with the required features have been produced and characterized, exploiting the potential of the pulsed laser deposition technique. In the intensity range 1016-1017 W cm-2, they allow us to obtain maximum proton energies 2-3 times higher compared to bare solid targets, able to reach and surpass the MeV range with both low and ultrahigh contrast pulses. The results of two-dimensional particle-in-cell simulations, supporting the interpretation of the experimental results, and directions to exploit the concept also at ultrahigh intensities, are presented.
BibTeX:
@article{Passoni2014,
  author = {Passoni, M and Zani, A and Sgattoni, A and Dellasega, D and Macchi, A and Prencipe, I and Floquet, V and Martin, P and Liseykina, T V and Ceccotti, T},
  title = {Energetic ions at moderate laser intensities using foam-based multi-layered targets},
  journal = {Plasma Physics and Controlled Fusion},
  year = {2014},
  volume = {56},
  number = {4},
  pages = {045001},
  url = {http://stacks.iop.org/0741-3335/56/i=4/a=045001},
  doi = {10.1088/0741-3335/56/4/045001}
}
"Laser plasma acceleration of electrons with multi-PW laser beams in the frame of CILEX"
Cros B, Paradkar B, Davoine X, Chancé A, Desforges F, Dobosz-Dufrénoy S, Delerue N, Ju J, Audet T, Maynard G, Lobet M, Gremillet L, Mora P, Schwindling J, Delferrière O, Bruni C, Rimbault C, Vinatier T, Di Piazza A, Grech M, Riconda C, Marquès J, Beck A, Specka A, Martin P, Monot P, Normand D, Mathieu F, Audebert P & Amiranoff F, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. La Biodola, Italie Vol. 740, pp. 27-33. Elsevier - (2014).
Abstract: Laser plasma acceleration of electrons has progressed along with advances in laser technology. It is thus expected that the development in the near-future of multi-PW-class laser and facilities will enable a vast range of scientific opportunities for laser plasma acceleration research. On one hand, high peak powers can be used to explore the extremely high intensity regime of laser wakefield acceleration, producing for example large amounts of electrons in the GeV range or generating high energy photons. On the other hand, the available laser energy can be used in the quasi-linear regime to create accelerating fields in large volumes of plasma and study controlled acceleration in a plasma stage of externally injected relativistic particles, either electrons or positrons. In the frame of the Centre Interdisciplinaire de la Lumière EXtrème (CILEX), the Apollon-10P laser will deliver two beams at the 1 PW and 10 PW levels, in ultra-short (View the MathML source) pulses, to a target area dedicated to electron acceleration studies, such as the exploration of the non-linear regimes predicted theoretically, or multi-stage laser plasma acceleration.
BibTeX:
@inproceedings{cros:in2p3-00903672,
  author = {Cros, B. and Paradkar, B.S. and Davoine, X. and Chancé, A. and Desforges, F.G. and Dobosz-Dufrénoy, S. and Delerue, N. and Ju, J. and Audet, T.L. and Maynard, G. and Lobet, M. and Gremillet, L. and Mora, P. and Schwindling, J. and Delferrière, O. and Bruni, C. and Rimbault, C. and Vinatier, T. and Di Piazza, A. and Grech, M. and Riconda, C. and Marquès, J.R. and Beck, A. and Specka, A. and Martin, Ph. and Monot, P. and Normand, D. and Mathieu, F. and Audebert, P. and Amiranoff, F.},
  editor = {Ralph Assmann, Massimo Ferrario, Jens Osterhoff, Arnd E. Specka },
  title = {Laser plasma acceleration of electrons with multi-PW laser beams in the frame of CILEX},
  booktitle = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  publisher = {Elsevier},
  year = {2014},
  volume = {740},
  pages = {27-33},
  note = {LAL/RT 13-48 },
  url = {http://hal.in2p3.fr/in2p3-00903672},
  doi = {10.1016/j.nima.2013.10.090}
}
"Ultrafast formation of hydrated electrons in water at high concentration: experimental evidence of the free electron"
Palianov P, Martin P, Quéré F and Pommeret S, Journal of Experimental and Theoretical Physics. Vol. Vol. 145 (3) - (2014).
Abstract: Using a time-resolved optical interferometric technique, we investigate the ultrafast primary events following the interaction of an ultrashort laser pulse with pure water in the TW/cm<sup>2</sup> regime. Because our method is sensitive to the quasi-instantaneous electron energy level position, we demonstrate that in contrast to the well-known low-intensity regime, where the free electrons are instantaneously captured by pre-existing traps, in this new regime of excitation, free electrons are clearly observed, exhibiting a substantial contribution in the near IR. The delayed localization is attributed to the saturation of pre-existing cavities in the liquid by the large number of the excited electron states created.
BibTeX:
@article{Palianov2014,
  author = {Palianov, P. and Martin, P.and Quéré, P. and Pommeret, S.},
  title = {ULTRAFAST FORMATION OF HYDRATED ELECTRONS IN WATER AT HIGH CONCENTRATION: EXPERIMENTAL EVIDENCE OF THE FREE ELECTRON},
  journal = {Journal of Experimental and Theoretical Physics},
  year = {2014},
  volume = {Vol. 145 (3)},
  url = {http://jetp.ac.ru/cgi-bin/e/index/r/145/3/p559?a=list}
}
"Investigation of amplitude spatio-temporal couplings at the focus of a 100 TW-25 fs laser"
Kahaly, Monchocé S, Gallet V, Gobert O, Réau F, Tcherbakoff O, D'Oliveira P. Martin P and Quéré F, Applied Physics Letters - (2014).
Abstract: We address the on target focal spot spatio-temporal features of an ultrashort, 100 TW class laser chain by using spectrally resolved imaging diagnostics. The observed spatio-spectral images, which we call rotating imaging spectrographs, are obtained single shot to reveal the essential information about the spatio-temporal couplings. We observe nontrivial effects in the focal plane due to compressor defects which significantly affect the maximum on target intensity. This diagnostic might become an essential tool for improving compressor alignment in many upcoming multi-petawatt short pulse laser facilities.
BibTeX:
@article{Kahaly2014,
  author = {Kahaly, and Monchocé, S. and Gallet, V. and Gobert, O. and Réau, F. and Tcherbakoff, O. and D'Oliveira, P. Martin, P. and Quéré, F},
  title = {Investigation of amplitude spatio-temporal couplings at the focus of a 100 TW-25 fs laser},
  journal = {Applied Physics Letters},
  year = {2014},
  url = {http://scitation.aip.org/content/aip/journal/apl/104/5/10.1063/1.4863828}
}
"Optical properties of relativistic plasma mirrors"
Vincenti H, Monchocé S., Kahaly S, Bonnaud G, Martin P and Quéré F, Nat Commun.,Vol. 5, pp. -. Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. - March, (2014).
Abstract: The advent of ultrahigh-power femtosecond lasers creates a need for an entirely new class of optical components based on plasmas. The most promising of these are known as plasma mirrors, formed when an intense femtosecond laser ionizes a solid surface. These mirrors specularly reflect the main part of a laser pulse and can be used as active optical elements to manipulate its temporal and spatial properties. Unfortunately, the considerable pressures exerted by the laser can deform the mirror surface, unfavourably affecting the reflected beam and complicating, or even preventing, the use of plasma mirrors at ultrahigh intensities. Here we derive a simple analytical model of the basic physics involved in laser-induced deformation of a plasma mirror. We validate this model numerically and experimentally, and use it to show how such deformation might be mitigated by appropriate control of the laser phase.
BibTeX:
@article{Vincenti2014,
  author = {Vincenti, H. and Monchocé, S., and Kahaly, S. and Bonnaud, G. and Martin, Ph. and Quéré,  F.},
  title = {Optical properties of relativistic plasma mirrors},
  journal = {Nat Commun},
  publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
  year = {2014},
  volume = {5},
  pages = {--},
  url = {http://dx.doi.org/10.1038/ncomms4403},
  doi = {10.1038/ncomms4403}
}
2013
"Evidence of Resonant Surface-Wave Excitation in the Relativistic Regime through Measurements of Proton Acceleration from Grating Targets"
Ceccotti T, Floquet V, Sgattoni A, Bigongiari A, Klimo O, Raynaud M, Riconda C, Heron A, Baffigi F, Labate L, Gizzi LA, Vassura L, Fuchs J, Passoni M, Kveton M, Novotny F, Possolt M, Prokupek J, Proska J, Psikal J, Stolcova L, Velyhan A, Bougeard M, D'Oliveira P, Tcherbakoff O, Reau F, Martin P and Macchi A, Phys. Rev. Lett., Vol. 111, pp. 185001. American Physical Society - Oct, (2013).
Abstract: The interaction of laser pulses with thin grating targets, having a periodic groove at the irradiated surface, has been experimentally investigated. Ultrahigh contrast (~ 1012) pulses allowed to demonstrate an enhanced laser-target coupling for the first time in the relativistic regime of ultra-high intensity > 1019 W/cm2. A maximum increase by a factor of 2.5 of the cut-off energy of protons produced by Target Normal Sheath Acceleration has been observed with respect to plane targets, around the incidence angle expected for resonant excitation of surface waves. A significant enhancement is also observed for small angles of incidence, out of resonance.
BibTeX:
@article{PhysRevLett.111.185001,
  author = {Ceccotti, T. and Floquet, V. and Sgattoni, A. and Bigongiari, A. and Klimo, O. and Raynaud, M. and Riconda, C. and Heron, A. and Baffigi, F. and Labate, L. and Gizzi, L. A. and Vassura, L. and Fuchs, J. and Passoni, M. and Kveton, M. and Novotny, F. and Possolt, M. and Prokupek, J. and ProÅ¡ka, J. and PÅ¡ikal, J. and Å tolcová, L. and Velyhan, A. and Bougeard, M. and D'Oliveira, P. and Tcherbakoff, O. and Reau, F. and Martin, P. and Macchi, A.},
  title = {Evidence of Resonant Surface-Wave Excitation in the Relativistic Regime through Measurements of Proton Acceleration from Grating Targets},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2013},
  volume = {111},
  pages = {185001},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.111.185001},
  doi = {10.1103/PhysRevLett.111.185001}
}
"Spectral characterization of laser-driven solid-based high harmonics in the coherent wake emission regime"
Van Tilborg J, Shaw BH, Sokollik T, Rykovanov S, Leemans WP, Monchocé S, Quéré F, Martin P and Malvache A, Optics Letters, Accepted - (2013).
Abstract: Laser-produced surface high harmonic generation (SHHG) is an attractive source of extreme ultra-violet radiation due to its coherent properties and high peak power. By operating at sub-relativistic laser intensities in the coherent wake emission regime, the harmonic spectrum was experimentally studied versus laser properties. At higher laser intensities (>1017 W/cm2) a higher spectral cut-off was observed, with accompanying blue-shifting and spectral broadening of the individual orders. A model based on an expanding critical-surface provides qualitative agreement to the observations.
BibTeX:
@article{Vantilborg2013,
  author = {Van Tilborg, J. and Shaw, B. H. and Sokollik,  T. and Rykovanov, S. and Leemans, W. P. and Monchocé, S. and Quéré, F. and Martin, Ph. and Malvache,  A.},
  title = {Spectral characterization of laser-driven solid-based high harmonics in the coherent wake emission regime},
  journal = {Optics Letters, Accepted (2013)},
  year = {2013},
  url = {http://www.opticsinfobase.org/view_article.cfm?gotourl=http%3A%2F%2Fwww%2Eopticsinfobase%2Eorg%2FDirectPDFAccess%2F88B73657%2DBF18%2DD2BE%2DDA2D00F96AD4A837%5Fads192293%2Epdf%3Fda%3D1%26adsid%3D192293%26journal%3D3%26seq%3D0%26mobile%3Dno&org=}
}
"Micro-sphere layered targets efficiency in laser driven proton acceleration"
Floquet V, Klimo O, Psikal J, Velyhan A, Limpouch J, Proska J, Novotny F, Stolcova L, Macchi A, Sgattoni A, Vassura L, Labate L, Baffigi F, Gizzi LA, Martin P and Ceccotti T, J. Appl. Phys., Vol. 114(8), pp. 083305-5. AIP - August, (2013).
Abstract: Proton acceleration from the interaction of high contrast, 25 fs laser pulses at >1019 W/cm2 intensity with plastic foils covered with a single layer of regularly packed micro-spheres has been investigated experimentally. The proton cut-off energy has been measured as a function of the micro-sphere size and laser incidence angle for different substrate thickness, and for both P and S polarization. The presence of micro-spheres with a size comparable to the laser wavelength allows to increase the proton cut-off energy for both polarizations at small angles of incidence (10°). For large angles of incidence, however, proton energy enhancement with respect to flat targets is absent. Analysis of electron trajectories in particle-in-cell simulations highlights the role of the surface geometry in the heating of electrons.
BibTeX:
@article{Floquet2013,
  author = {Floquet, V. and Klimo, O. and Psikal, J. and Velyhan, A. and Limpouch, J. and Proska, J. and Novotny, F. and Stolcova, L. and Macchi, A. and Sgattoni, A. and Vassura, L. and Labate, L. and Baffigi, F. and Gizzi, L. A. and Martin, Ph. and Ceccotti, T.},
  title = {Micro-sphere layered targets efficiency in laser driven proton acceleration},
  journal = {J. Appl. Phys.},
  publisher = {AIP},
  year = {2013},
  volume = {114},
  number = {8},
  pages = {083305--5},
  url = {http://dx.doi.org/10.1063/1.4819239},
  doi = {10.1063/1.4819239}
}
"Direct Observation of Density-Gradient Effects in Harmonic Generation from Plasma Mirrors"
Kahaly S, Monchocé S, Vincenti H, Dzelzainis T, Dromey B, Zepf M, Martin P and Quéré F , Phys. Rev. Lett., Vol. 110, pp. 175001. American Physical Society - Apr, (2013).
Abstract: High-order harmonics and attosecond pulses of light can be generated when ultraintense, ultrashort laser pulses reflect off a solid-density plasma with a sharp vacuum interface, i.e., a plasma mirror. We demonstrate experimentally the key influence of the steepness of the plasma-vacuum interface on the interaction, by measuring the spectral and spatial properties of harmonics generated on a plasma mirror whose initial density gradient scale length L is continuously varied. Time-resolved interferometry is used to separately measure this scale length.
BibTeX:
@article{PhysRevLett.110.175001,
  author = {Kahaly, S. and Monchocé, S. and Vincenti,H. and Dzelzainis, T. and Dromey, B.  and Zepf,  M. and Martin, Ph. and Quéré, F.},
  title = {Direct Observation of Density-Gradient Effects in Harmonic Generation from Plasma Mirrors},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2013},
  volume = {110},
  pages = {175001},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.110.175001},
  doi = {10.1103/PhysRevLett.110.175001}
}
2012
"First measurements of laser-accelerated proton induced luminescence"
Floquet V, Ceccotti T, Dobosz Dufrénoy S, Bonnaud G, Gremillet L, Monot P and Martin P, Physics of Plasmas., Vol. 19(9), pp. 094501 - September, (2012).
Abstract: We present our first results about laser-accelerated proton induced luminescence in solids. In the first part, we describe the optimization of the proton source as a function of the target thickness as well as the laser pulse duration and energy. Due to the ultra high contrast ratio of our laser beam, we succeeded in using targets ranging from the micron scale down to nanometers thickness. The two optimal thicknesses we put in evidence are in good agreement with numerical simulations. Laser pulse duration shows a small influence on proton maximum energy, whereas the latter turns out to vary almost linearly as a function of laser energy. Thanks to this optimisation work, we have been able to acquire images of the proton energy deposition in a solid scintillator.
BibTeX:
@article{Floquet2012,
  author = {Floquet, V. and Ceccotti, T. and Dobosz Dufrénoy, S. and Bonnaud, G. and Gremillet, L. and Monot, P. and Martin, Ph.},
  title = {First measurements of laser-accelerated proton induced luminescence},
  journal = {Physics of Plasmas},
  year = {2012},
  volume = {19},
  number = {9},
  pages = {094501},
  doi = {10.1063/1.4753939}
}
List created by JabRef on 10/11/2017.


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