Faculty Profiles - HISHIKAWA, Akiyoshi

Papers - HISHIKAWA, Akiyoshi

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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

Ultrafast two-photon Rabi oscillations in excited He driven by femtosecond intense laser fields Reviewed

A. Hishikawa, M. Fushitani, C. N. Liu, A. Matsuda, T. Endo, Y. Toida, Y. Hikosaka, T. Morishita

XXIX INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC, AND ATOMIC COLLISIONS (ICPEAC2015), PTS 1-12 Vol. 635 ( 9 ) 2015

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

We demonstrate ultrafast multiphoton coherent excitation in near-infrared intense laser fields (<= 10 TW/cm(2)) using excited helium in the 1s2p (P-1) state as the target. Strong two-photon coupling between the 2p state and the 5f and 6f Rydberg states drives ultrafast Rabi oscillations in tens of femtosecond. Theoretical calculations solving the time-dependent Schrodinger equation were carried out to elucidate the strong field effects.

DOI： 10.1088/1742-6596/635/9/092082

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

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

Five-photon sequential double ionization of He in intense extreme-ultraviolet free-electron laser fields Reviewed

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

PHYSICAL REVIEW A Vol. 90 ( 5 ) page： 053403 2014.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

A multiphoton ionization process of He in intense extreme ultraviolet free-electron laser fields is investigated in a photon energy range of hv = 20.1-20.8 eV using shot-by-shot photoelectron spectroscopy. A photoelectron peak resulting from sequential double ionization of He due to five-photon absorption is observed around hv = 20.4. Shot-by-shot analysis of photoelectron spectra shows that two-photon resonance to the He+(2s S-2) state from the He+ ground state is responsible for the substantial enhancement of five-photon double ionization. Effective cross sections for two-photon absorption between the 1s and 2s states of He+ and for one-photon absorption from the He+ 2s state are obtained.

DOI： 10.1103/PhysRevA.90.053403

Photoelectron-photoion correlation in ultrafast multichannel photoionization of Ar Reviewed

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

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Vol. 47 ( 19 ) page： 195602 2014.10

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

Ultrafast multichannel single-photon ionization of Ar is investigated theoretically by a model calculation incorporating correlation between the photoelectron and photoion. It is shown that the coherent hole dynamics in Ar+ associated with a superposition of the spin-orbit states can be observed by using a Fourier-transform limited laser pulse for ionization, while the coherence is degraded or lost by chirped a laser pulse. We demonstrate that the coherent hole dynamics can be retrieved even in the case of ionization by a chirped laser pulse, by labeling the photoion dynamics with the counterpart photoelectron energy.

DOI： 10.1088/0953-4075/47/19/195602

Time-resolved laser Coulomb explosion imaging using few-cycle intense laser pulses: Application to exploding CS2 in highly charged states Reviewed

Akitaka Matsuda, Eiji J. Takahashi, Akiyoshi Hishikawa

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Vol. 195 page： 327 - 331 2014.8

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER

Ion-coincidence momentum imaging of three-body Coulomb explosion of CS2, CS2z+ -> Sp+ + Cq+ + Sr+ (z = p + q + r), in few-cycle intense laser fields (9 fs, similar to 10(15) W/cm(2)) is presented. It is shown that the momentum distributions of fragment ions produced from CS210+ are well reproduced by a classical explosion model incorporating the coordinate and momentum distributions of the initial ground vibrational state of CS2. On the other hand, a significant deviation is observed for CS23+ due to the non-Coulombic character of the potential energy surfaces. Coulomb explosion imaging is applied to real-time probing of Coulomb exploding CS2 in highly charged states, using a pair of intense few-cycle laser pulses. It is shown that the explosion proceeds in a different time scale depending on the charge state, mostly along the linear geometry during the bond-breaking of the two C S bonds. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elspec.2013.12.011

Preface Reviewed

Hiroshi Daimon, Akiyoshi Hishikawa, Catalin Miron

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Vol. 195 page： 285 - 286 2014.8

Special issue on ultrafast electron and molecular dynamics Preface Reviewed Open Access

Fernando Martin, Akiyoshi Hishikawa, Marc Vrakking

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Vol. 47 ( 12 ) 2014.6

Dissociative ionization of NO in few-cycle intense laser fields : Effects of pi-sigma electronic transition Reviewed

Tomoyuki Endo, Mizuho Fushitani, Akitaka Matsuda, Akiyoshi Hishikawa

XXVIII INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC AND ATOMIC COLLISIONS (ICPEAC) Vol. 488 ( SECTION 3 ) 2014

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

Dissociative ionization (DI) of NO in few-cycle intense laser fields was investigated by using the 3D momentum imaging method. It was found that the symmetry change in the outermost occupied molecular orbital upon the pi - sigma electronic transition is clearly reflected in the spatial anisotropy of the fragment ion, N+.

DOI： 10.1088/1742-6596/488/3/032025

Two-photon rabi oscillations of excited he atoms in ultrafast strong laser field ionization Reviewed

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

Optics InfoBase Conference Papers 2014

Resolving the enhanced nonlinear double excitation of helium in intense ultra-short extreme-ultraviolet pulses Reviewed

Chien-Nan Liu, Akiyoshi Hishikawa, Toru Morishita

XXVIII INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC AND ATOMIC COLLISIONS (ICPEAC) Vol. 488 ( SECTION 3 ) 2014

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

We present a theoretical study for multiphoton double excitation of He atoms exposed to an intense ultrashort extreme-ultraviolet (EUV) pulse, where the photon energy coincides with the transition energy from the ground state to a Rydberg state. We identify the mechanism of the enhanced three-photon absorption probability as observed in the experiment.

DOI： 10.1088/1742-6596/488/3/032047

Determination of absolute cross-sections of nonresonant EUV-UV two-color two-photon ionization of he

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

Optics InfoBase Conference Papers 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Optical Society of America (OSA)

Single-shot photoelectron spectroscopy was performed for nonresonant EUV-UV twocolor two-photon ionization of He. From data analysis on the shot-by-shot basis, the absolute cross-section was determined to be σ(2)(597nm, 268nm) = 4.1(6)×10-52 cm4 s. © 2014 OSA.

DOI： 10.1364/up.2014.08.tue.p2.5

Ultrafast photoelectron spectroscopy of electron-ion wave packets in Rydberg N2

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

Optics InfoBase Conference Papers 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Optical Society of America (OSA)

Time-resolved photoelectron spectroscopy of N2 Rydberg using single-order high harmonics at 80 nm reveals ultrafast wavepacket dynamics (~3 fs) of both Rydberg electron and the corresponding N2 + core as the beating oscillation (~ 300 fs). © 2014 OSA.

DOI： 10.1364/up.2014.07.mon.p1.5

Ultrafast coulomb explosion of formaldehyde in 7 and 35 fs intense laser fields studied by triple ion-coincidence momentum imaging

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

Optics InfoBase Conference Papers 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Optical Society of America (OSA)

Ultrafast three-body Coulomb explosion of formaldehyde (H2CO) in intense laser fields has been studied. The pulse duration dependence of the Newton plot of the fragment ions revealed the ultrafast molecular dynamics in the dication states. © 2014 OSA.

DOI： 10.1364/up.2014.09.wed.p3.23

Two-photon rabi oscillations of excited he atoms in ultrafast strong laser field ionization

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

Optics InfoBase Conference Papers 2014

Time-resolved Coulomb explosion imaging of ultrafast fragmentation of CS2 in highly charged states

Akitaka Matsuda, Eiji J. Takahashi, Akiyoshi Hishikawa

Optics InfoBase Conference Papers 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Optical Society of America (OSA)

Time-resolved Coulomb explosion imaging of CS2 in few-cycle intense laser fields revealed that the ultrafast fragmentation dynamics of CS2 in highly charged states proceed in a different timescale depending on the charge state. © 2014 OSA.

DOI： 10.1364/up.2014.08.tue.p2.18

Nonresonant EUV-UV two-color two-photon ionization of He studied by single-shot photoelectron spectroscopy Reviewed

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

PHYSICAL REVIEW A Vol. 88 ( 6 ) page： 063422 2013.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

Single-shot photoelectron spectroscopy of nonresonant two-color two-photon ionization of He has been carried out using an intense free-electron laser (FEL) at 59.7 nm and a femtosecond UV laser at 268 nm. By shot-by-shot analysis of photoelectron spectra, the cross section for nonresonant two-color ionization of He is determined to be sigma((2)) = 4.1(6) x 10(-52) cm(4) s. The cross-correlation trace derived from the nonresonant signals shows that the temporal resolution of the system is 0.36(3) ps, which is mainly governed by the timing jitter between the FEL and UV laser pulses.

DOI： 10.1103/PhysRevA.88.063422

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