ORCID Profile
0000-0002-2492-4676
Current Organisation
Nara Women's University
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Publisher: American Physical Society (APS)
Date: 25-02-2020
Publisher: MDPI AG
Date: 08-02-2023
DOI: 10.3390/APP13042176
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.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2016
Publisher: Springer Science and Business Media LLC
Date: 16-05-2019
DOI: 10.1038/S41467-019-10060-Z
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.
Publisher: American Physical Society (APS)
Date: 30-12-2016
Publisher: MDPI AG
Date: 16-06-2017
DOI: 10.3390/APP7060621
Publisher: IOP Publishing
Date: 07-09-2015
Publisher: American Physical Society (APS)
Date: 31-05-2018
Publisher: American Physical Society (APS)
Date: 19-01-2017
No related grants have been discovered for Yoshiaki Kumagai.