Faculty Profiles - HISHIKAWA, Akiyoshi

Papers - HISHIKAWA, Akiyoshi

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Capturing roaming molecular fragments in real time Reviewed International coauthorship International journal

Tomoyuki Endo, Simon P. Neville, Vincent Wanie, Samuel Beaulieu, Chen Qu, Jude Deschamps, Philippe Lassonde, Bruno E. Schmidt, Hikaru Fujise, Mizuho Fushitani, Akiyoshi Hishikawa, Paul L. Houston, Joel M. Bowman, Michael S. Schuurman, François Lé garé, Heide Ibrahim

Science Vol. 370 ( 6520 ) page： 1072 - + 2020.11

Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science ({AAAS})

<jats:p>Since the discovery of roaming as an alternative molecular dissociation pathway in formaldehyde (H<jats:sub>2</jats:sub>CO), it has been indirectly observed in numerous molecules. The phenomenon describes a frustrated dissociation with fragments roaming at relatively large interatomic distances rather than following conventional transition-state dissociation; incipient radicals from the parent molecule self-react to form molecular products. Roaming has been identified spectroscopically through static product channel–resolved measurements, but not in real-time observations of the roaming fragment itself. Using time-resolved Coulomb explosion imaging (CEI), we directly imaged individual “roamers” on ultrafast time scales in the prototypical formaldehyde dissociation reaction. Using high-level first-principles simulations of all critical experimental steps, distinctive roaming signatures were identified. These were rendered observable by extracting rare stochastic events out of an overwhelming background using the highly sensitive CEI method.</jats:p>

DOI： 10.1126/science.abc2960

Capturing roaming fragments in real time: A molecular road movie

Endo T., Neville S.P., Wanie V., Beaulieu S., Qu C., Deschamps J., Lassonde P., Schmidt B.E., Fujise H., Fushitani M., Hishikawa A., Houston P.L., Bowman J.M., Schuurman M.S., Légaré F., Ibrahim H.

Optics InfoBase Conference Papers 2020.11

Ultrafast Reaction Imaging and Control by Ultrashort Intense Laser Pulses Invited Reviewed

Akiyoshi Hishikawa, Akitaka Matsuda, Mizuho Fushitani

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN Vol. 93 ( 11 ) page： 1293 - 1304 2020.11

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

Molecules irradiated with intense laser pulses (field intensity similar to 10(15) W/cm(2)) exhibit a variety of characteristic processes, such as tunneling ionization, electron rescattering, high-order harmonics generation and Coulomb explosion, that cannot be seen in a weak light field. These features have attracted attention in the last decades as they provide unique approaches to visualize and manipulate ultrafast dynamics of atoms and molecules. Here we discuss molecular processes in intense laser fields, with focuses on the applications to ultrafast imaging and control of reaction dynamics.

DOI： 10.1246/bcsj.20200158

Characterization of soft X-ray FEL pulse duration with two-color photoelectron spectroscopy Reviewed

Shigeki Owada, Mizuho Fushitani, Akitaka Matsuda, Hikaru Fujise, Yuuma Sasaki, Yasumasa Hikosaka, Akiyoshi Hishikawa, Makina Yabashi

JOURNAL OF SYNCHROTRON RADIATION Vol. 27 ( 5 ) page： 1362 - 1365 2020.9

Language：English Publishing type：Research paper (scientific journal) Publisher：INT UNION CRYSTALLOGRAPHY

The pulse duration of soft X-ray free-electron laser (FEL) pulses of SACLA BL1 (0.2-0.3 nC per bunch, 0.5-0.8 MeV) were characterized by photoelectron sideband measurements. The intensity of the He 1 s(-1) photoelectron sidebands generated by a near-infrared femtosecond laser was measured as a function of the time delay between the two pulses using an arrival time monitor. From the width of the cross-correlation trace thus derived, the FEL pulse duration was evaluated to be 28 +/- 5 fs full width at half-maximum in the photon energy range between 40 eV and 120 eV.

DOI： 10.1107/S1600577520008516

Multielectron-Ion Coincidence Spectroscopy of Xe in Extreme Ultraviolet Laser Fields: Nonlinear Multiple Ionization via Double Core-Hole States Reviewed International journal

M. Fushitani, Y. Sasaki, A. Matsuda, H. Fujise, Y. Kawabe, K. Hashigaya, S. Owada, T. Togashi, K. Nakajima, M. Yabashi, Y. Hikosaka, A. Hishikawa

Physical Review Letters Vol. 124 ( 19 ) 2020.5

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Physical Society ({APS})

DOI： 10.1103/PhysRevLett.124.193201

Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.124.193201/fulltext

Angle dependence of dissociative tunneling ionization of NO in asymmetric two-color intense laser fields Reviewed

Tomoyuki Endo, Hikaru Fujise, Hiroka Hasegawa, Akitaka Matsuda, Mizuho Fushitani, Oleg I. Tolstikhin, Toru Morishita, Akiyoshi Hishikawa

Physical Review A Vol. 100 ( 5 ) page： 053422 2019.11

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal)

© 2019 American Physical Society. Dissociative tunneling ionization of nitric oxide (NO) in linearly polarized phase-locked two-color femtosecond intense laser fields (45 fs, λ=800 and 400 nm, total field intensity I=1×1014W/cm2) has been studied by three-dimensional ion momentum imaging. The N+ fragment produced by the dissociative ionization, NO→NO++e-→N++O+e-, exhibits a butterflylike momentum distribution peaked at finite angles with respect to the laser polarization direction. In addition, a clear dependence on the relative phase between the two laser fields is observed, showing that the tunneling ionization occurs efficiently when the electric field points from N to O. For the highest kinetic energy component, the observed orientation dependence is well explained with theoretical calculations by the weak-field asymptotic theory for the 2πhighest occupied molecular orbital (HOMO). On the other hand, the peak angle shifts toward the laser polarization direction as the kinetic energy decreases, indicating that pathways other than direct ionization from the HOMO contribute to the dissociative ionization.

DOI： 10.1103/PhysRevA.100.053422

Probing Rydberg-Rydberg interactions in N<inf>2</inf> by ultrafast EUV-NIR photoelectron spectroscopy Reviewed International coauthorship

Fushitani, M., Toida, Y., Légaré, F., Hishikawa, A.

Optics Express Vol. 27 ( 14 ) page： 19702 - 19711 2019.7

Coincidence momentum imaging of four- and three-body Coulomb explosion of formaldehyde in ultrashort intense laser fields Reviewed International coauthorship

Chien-Ming Tseng, Mizuho Fushitani, Akitaka Matsuda, Akiyoshi Hishikawa

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Vol. 228 page： 25 - 30 2018.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Ion-coincidence momentum imaging of Coulomb explosion of formaldehyde (H2CO) in femtosecond intense laser fields (800 nm, 1.3 x 10(15) W/cm(2)) is performed with two different laser pulse durations (7 fs and 35 fs). In the 7-fs laser fields, the full fragmentation pathway from H2CO4+ -> H+ + H+ + C+ + O+ is identified. The angles between the fragment momenta are well reproduced by a simple Coulomb explosion model from the geometry of neutral formaldehyde, showing that the molecular structure is virtually frozen along the bending coordinates during the multiple ionization. Three-body Coulomb explosion pathways from triply charged states, H2CO3+ -> H+ + H+ + C+ + O+, are observed in both the 7-fs and 35-fs laser fields. Significant changes in the momentum angle distribution and asymmetric energy partitioning between two H+ ions are observed in the 35-fs case, which are attributed to structural deformation prior to the Coulomb explosion in the longer pulse.

DOI： 10.1016/j.elspec.2018.07.001

Femtosecond laser filamentation in gaseous ethylene: Formation of hydrogenated amorphous carbon Reviewed

A. Matsuda, T. Hayashi, R. Kitaura, A. Hishikawa

Chem. Lett. Vol. 46 page： 1426-1429 2017.7

Selective bond breaking of CO2 in phase-locked two-color intense laser fields: laser field intensity dependence Reviewed

Tomoyuki Endo, Hikaru Fujise, Yuuna Kawachi, Ayaka Ishihara, Akitaka Matsuda, Mizuho Fushitani, Hirohiko Kono, Akiyoshi Hishikawa

PHYSICAL CHEMISTRY CHEMICAL PHYSICS Vol. 19 ( 5 ) page： 3550 - 3556 2017.2

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

Selective bond breaking of CO2 in phase-locked omega-2 omega two-color intense laser fields (lambda = 800 nm and 400 nm, total field intensity l similar to 10(14) W cm(-2)) has been investigated by coincidence momentum imaging. The CO+ and O+ fragment ions produced by two-body Coulomb explosion, CO22+ -> CO+ + O+, exhibit asymmetric distributions along the laser polarization direction, showing that one of the two equivalent C-O bonds is selectively broken by the laser fields. At a field intensity higher than 2 x 10(14) W cm(-2), the largest fragment asymmetry is observed when the relative phase phi between the omega and 2 omega laser fields is similar to 0 and pi. On the other hand, an increase of the asymmetry and a shift of the phase providing the largest asymmetry are observed at lower field intensities. The selective bond breaking and its dependence on the laser field intensity are discussed in terms of a mechanism involving deformation of the potential energy surfaces and electron recollision in intense laser fields.

DOI： 10.1039/c6cp07471e

Single-order laser high harmonics in XUV for ultrafast photoelectron spectroscopy of molecular wavepacket dynamics Reviewed

Fushitani, M., Hishikawa, A.

Structural Dynamics Vol. 3 ( 6 ) page： 062602 2016.11

Imaging Electronic Excitation of NO by Ultrafast Laser Tunneling Ionization Reviewed

Tomoyuki Endo, Akitaka Matsuda, Mizuho Fushitani, Tomokazu Yasuike, Oleg I. Tolstikhin, Toru Morishita, Akiyoshi Hishikawa

PHYSICAL REVIEW LETTERS Vol. 116 ( 16 ) page： 163002 2016.4

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

Tunneling-ionization imaging of photoexcitation of NO has been demonstrated by using few-cycle near-infrared intense laser pulses (8 fs, 800 nm, 1.1 x 10(14) W/cm(2)). The ion image of N+ fragment ions produced by dissociative ionization of NO in the ground state, NO (X-2 Pi; 2 pi) -> NO+ + e(-) -> N+ + O + e(-), exhibits a characteristic momentum distribution peaked at 45 degrees with respect to the laser polarization direction. On the other hand, a broad distribution centered at similar to 0 degrees appears when the A(2)Sigma(+) (3s sigma) excited state is prepared as the initial state by deep-UV photoexcitation. The observed angular distributions are in good agreement with the corresponding theoretical tunneling ionization yields, showing that the fragment anisotropy reflects changes of the highest-occupied molecular orbital by photoexcitation.

DOI： 10.1103/PhysRevLett.116.163002

Photoelectron sidebands induced by a chirped laser field for shot-by-shot temporal characterization of FEL pulses Reviewed

Chien-Nan Liu, Toru Morishita, Mizuho Fushitani, Akiyoshi Hishikawa

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Vol. 49 ( 3 ) page： 034005 2016.2

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

We theoretically investigate the laser-assisted photoionization of He by an extreme ultra violet (XUV) pulse in the presence of a linearly chirped intense laser pulse by solving the time-dependent Schrodinger equation within the single-active-electron approximation. Analysis based on the time-dependent perturbation theory is also carried out to provide more physical insights. A new scheme is shown to be capable of extracting the arrival time of an XUV free-electron laser (FEL) pulse relative to an external laser pulse as well as the XUV pulse duration from the photoelectron sidebands resulting from XUV ionization in the presence of a chirped laser pulse. This scheme is independent of the energy fluctuation and the timing jittering of the FEL pulse. Therefore it can be implemented in a non-invasive way to characterize FEL pulses on a shot-by-shot basis in time-resolved spectroscopy.

DOI： 10.1088/0953-4075/49/3/034005

Coincidence momentum imaging of asymmetric Coulomb explosion of CO2 in phase-locked two-color intense laser fields Reviewed

Tomoyuki Endo, Hikaru Fujise, Akitaka Matsuda, Mizuho Fushitani, Hirohiko Kono, Akiyoshi Hishikawa

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Vol. 207 page： 50 - 54 2016.2

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Coulomb explosion of CO2, CO2 -> CO2+2 + 2e(-) -> CO+ + O +2e(-), in phase-locked two-color ultrashort intense laser fields (800 nm and 400 nm, similar to 10(14) W/cm(2)) has been investigated by coincidence momentum imaging. The momentum images of the O+ and CO+ fragments show asymmetric distributions along the laser polarization direction depending on the relative phase of the two-color laser fields. The fragment asymmetry becomes most prominent (similar to 4%) at the relative phases providing the largest asymmetry of the electric field amplitude, with the O+ fragments preferentially ejected to the stronger field side. The mechanism of the asymmetric bond breaking of the two equivalent C-O bonds is discussed in terms of the nuclear dynamics in CO22+. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elspec.2015.12.010

Femtosecond two-photon Rabi oscillations in excited He driven by ultrashort intense laser fields Reviewed

M. Fushitani, C. -N. Liu, A. Matsuda, T. Endo, Y. Toida, M. Nagasono, T. Togashi, M. Yabashi, T. Ishikawa, Y. Hikosaka, T. Morishita, A. Hishikawa

NATURE PHOTONICS Vol. 10 ( 2 ) page： 102 - + 2016.2

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Coherent light-matter interaction provides powerful methods for manipulating quantum systems(1-3). Rabi oscillation is one such process. As it enables complete population transfer to a target state, it is thus routinely exploited in a variety of applications in photonics, notably quantum information processing(4,5). The extension of coherent control techniques to the multiphoton regime offers wider applicability, and access to highly excited or dipole-forbidden transition states. However, the multiphoton Rabi process is often disrupted by other competing nonlinear effects such as the a.c. Stark shift, especially at the high laser-field intensities necessary to achieve ultrafast Rabi oscillations(6). Here we demonstrate a new route to drive two-photon Rabi oscillations on timescales as short as tens of femtoseconds, by utilizing the strong-field phenomenon known as Freeman resonance(7). The scenario is not specific to atomic helium as investigated in the present study, but broadly applicable to other systems, thus opening new prospects for the ultrafast manipulation of Rydberg states(8).

DOI： 10.1038/NPHOTON.2015.228

Correlation between Photoeletron and Photoion in Ultrafast Multichannel Photoionization of Ar Reviewed

R. Itakura, M. Fushitani, A. Hishikawa, T. Sako

INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2015 (ICCMSE 2015) Vol. 1702 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

We theoretically investigate coherent dynamics of ions created through ultrafast multichannel photoionization from a viewpoint of photoelectron-photoion correlation. The model calculation on single-photon ionization of Ar reveals that the coherent hole dynamics in Ar+ associated with a superposition of the spin-orbit states P-2(J) (J = 3/2 and 1/2) can be identified by monitoring only the photoion created by a Fourier-transform limited extreme ultraviolet (EUV) pulse with the 9-fs pulse duration, while the coherence is lost by a chirped EUV pulse. It is demonstrated that by coincidence detection of the photoelectron and photoion the coherent hole dynamics can be extracted even in the case of ionization by a chirped EUV pulse with the sufficiently wide bandwidth.

DOI： 10.1063/1.4938829

Ion-Coincidence Momentum Imaging of Three-Body Coulomb Explosion of Formaldehyde in Ultrashort Intense Laser Fields Reviewed

M. Fushitani, C-M. Tseng, A. Matsuda, A. Hishikawa

INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2015 (ICCMSE 2015) Vol. 1702 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

Three-body Coulomb explosion of formaldehyde (H2CO) in intense 7- and 35-fs laser fields (1.3 x 10(15) W/cm(2)) has been investigated by using ion-coincidence momentum imaging technique. Two types of explosion pathways from the triply charged state, H2CO3+ -> (i) H+ + H+ + CO+ and (ii) H+ + CH+ + O+, have been identified. It is shown from the momentum correlation of the fragment ions of pathway (i), that the geometrical structure of the molecule is essentially frozen along the H-C-H bending coordinate for the 7-fs case. On the other hand, for a longer pulse duration (35 fs), structural deformation along the C-H stretching and H-C-H bending coordinates is identified, which is ascribed to the nuclear dynamics in the dication states populated within the laser pulse duration.

DOI： 10.1063/1.4938821

Fragment anisotropy on dissociative ionization of NO in two-color intense laser fields Reviewed

Tomoyuki Endo, Ayaka Ishihara, Akitaka Matsuda, Mizuho Fushitani, Akiyoshi Hishikawa

XXIX INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC, AND ATOMIC COLLISIONS (ICPEAC2015), PTS 1-12 Vol. 635 ( 11 ) 2015

Language：Japanese Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD

Dissociative-ionization of NO, NO -> NO+ + e(-) -> N+ + O + e(-), in omega-2 omega two-color phase-controlled intense laser fields was investigated by three-dimensional ion momentum imaging. The moment Urn image of the N+ ion exhibited anisotropic distributions peaked at 35 degrees against the laser polarization, which show clear left-right asymmetry depending on the omega-2 omega relative phase. The present study demonstrates that the molecular orbital can be retrieved by distinguishing the difference between the N and O side from the fragment anisotropy by intense laser pulses.

DOI： 10.1088/1742-6596/635/11/112027

Determination of Absolute Cross-Sections of Nonresonant EUV-UV Two-Color Two-Photon Ionization of He Reviewed

M. Fushitani, Y. Hikosaka, A. Matsuda, T. Endo, E. Shigemasa, M. Nagasono, T. Sato, T. Togashi, M. Yabashi, T. Ishikawa, A. Hishikawa

ULTRAFAST PHENOMENA XIX Vol. 162 page： 109 - 112 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER-VERLAG BERLIN

Single-shot photoelectron spectroscopy was performed for nonresonant EUV-UV two-color two-photon ionization of He. From data analysis on the shot-by-shot basis, the absolute cross-section was determined to be sigma((2))(59.7 nm, 268 nm) = 4.1(6) x 10(-52) cm(4) s.

DOI： 10.1007/978-3-319-13242-6_26

Time-Resolved Coulomb Explosion Imaging of Ultrafast Fragmentation of CS2 in Highly Charged States Reviewed

Akitaka Matsuda, Eiji J. Takahashi, Akiyoshi Hishikawa

ULTRAFAST PHENOMENA XIX Vol. 162 page： 168 - 171 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER-VERLAG BERLIN

Time-resolved three-body Coulomb explosion imaging of dissociating CS2 in few-cycle intense laser fields (9 fs, 4 x 10(15) W/cm(2)) is performed. It is revealed that the ultrafast fragmentation dynamics of CS2 in highly charged states proceed in a different timescale depending on the charge state.

DOI： 10.1007/978-3-319-13242-6_40

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