Faculty Profiles - HISHIKAWA, Akiyoshi

State-selective dissociative double ionization of CH3I and CH2I2 via I 4d core-hole states studied by multi-electron–ion coincidence spectroscopy Reviewed

Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevResearch.6.043323/fulltext

Ion-core switching in Rydberg series of XeKr Reviewed

Fukuda, Y., Szidarovszky, T., Nakata, M., Hishikawa, A., Yamanouchi, K.

Molecular Physics Vol. 122 ( 15-16 ) 2024.8

Mizuho Fushitani, Yasumasa Hikosaka, Motomichi Tashiro, Akiyoshi Hishikawa

The Journal of Chemical Physics Vol. 160 ( 17 ) 2024.5

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：AIP Publishing

The dissociative double ionization of CH3I and CH2I2 irradiated with extreme ultraviolet light at hv = 100 eV is investigated by multi-electron–ion coincidence spectroscopy using a magnetic bottle type electron spectrometer. The spin–orbit state-resolved Auger electron spectra for the I 4d core-hole states, (I 4d3/2)−1 and (I 4d5/2)−1, provide clear identifications of electronic states of CH3I2+ and CH2I22+. The dominant ion species produced after the double ionization correlate with the Auger electron energy, showing that different fragmentation pathways are open depending on the electronic states populated by the Auger decay. Theoretical calculations are performed to understand the fragmentation from the doubly charged states and the observed spin–orbit specificity in the Auger decay.

DOI： 10.1063/5.0204769

Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization Reviewed Open Access

Weronika O. Razmus, Felix Allum, James Harries, Yoshiaki Kumagai, Kiyonobu Nagaya, Surjendu Bhattacharyya, Mathew Britton, Mark Brouard, Philip H. Bucksbaum, Kieran Cheung, Stuart W. Crane, Mizuho Fushitani, Ian Gabalski, Tatsuo Gejo, Aaron Ghrist, David Heathcote, Yasumasa Hikosaka, Akiyoshi Hishikawa, Paul Hockett, Ellen Jones, Edwin Kukk, Hiroshi Iwayama, Huynh V. S. Lam, Joseph W. McManus, Dennis Milesevic, Jochen Mikosch, Shinichirou Minemoto, Akinobu Niozu, Andrew J. Orr-Ewing, Shigeki Owada, Daniel Rolles, Artem Rudenko, Dave Townsend, Kiyoshi Ueda, James Unwin, Claire Vallance, Anbu Venkatachalam, Shin-ichi Wada, Tiffany Walmsley, Emily M. Warne, Joanne L. Woodhouse, Michael Burt, Michael N. R. Ashfold, Russell S. Minns, Ruaridh Forbes

Physical Chemistry Chemical Physics Vol. 26 ( 16 ) page： 12725 - 12737 2024.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)

The dissociation dynamics of UV pumped iodothiophene molecules are investigated using velocity map ion imaging, in combination with site-selective extreme ultraviolet ionization of the iodine atom.

DOI： 10.1039/d3cp06079a

Wave packet dynamics and control in excited states of molecular nitrogen Reviewed International coauthorship

Mizuho Fushitani, Hikaru Fujise, Akiyoshi Hishikawa, Daehyun You, Shu Saito, Yu Luo, Kiyoshi Ueda, Heide Ibrahim, Francois Légaré, Stephen T. Pratt, Per Eng-Johnsson, Johan Mauritsson, Anna Olofsson, Jasper Peschel, Emma R. Simpson, Paolo Antonio Carpeggiani, Dominik Ertel, Praveen Kumar Maroju, Matteo Moioli, Giuseppe Sansone, Ronak Shah, Tamás Csizmadia, Mathieu Dumergue, Harshitha Nandiga Gopalakrishna, Sergei Kühn, Carlo Callegari, Miltcho Danailov, Alexander Demidovich, Lorenzo Raimondi, Marco Zangrando, Giovanni De Ninno, Michele Di Fraia, Luca Giannessi, Oksana Plekan, Primoz Rebernik Ribic, Kevin C. Prince

The Journal of Chemical Physics Vol. 160 ( 10 ) 2024.3

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

Wave packet interferometry with vacuum ultraviolet light has been used to probe a complex region of the electronic spectrum of molecular nitrogen, N2. Wave packets of Rydberg and valence states were excited by using double pulses of vacuum ultraviolet (VUV), free-electron-laser (FEL) light. These wave packets were composed of contributions from multiple electronic states with a moderate principal quantum number (n ∼ 4–9) and a range of vibrational and rotational quantum numbers. The phase relationship of the two FEL pulses varied in time, but as demonstrated previously, a shot-by-shot analysis allows the spectra to be sorted according to the phase between the two pulses. The wave packets were probed by angle-resolved photoionization using an infrared pulse with a variable delay after the pair of excitation pulses. The photoelectron branching fractions and angular distributions display oscillations that depend on both the time delays and the relative phases of the VUV pulses. The combination of frequency, time delay, and phase selection provides significant control over the ionization process and ultimately improves the ability to analyze and assign complex molecular spectra.

DOI： 10.1063/5.0188182

Imaging Ultrafast Dissociation Dynamics: OCS & Roaming in Formaldehyde International coauthorship Open Access

Endo, T; Neville, SP; Ziems, KM; Lassonde, P; Qu, C; Schmidt, BE; Fujise, H; Fushitani, M; Hishikawa, A; Grafe, S; Houston, PL; Bowman, JM; Schuurman, MS; Legare, F; Ibrahim, H

PROCEEDINGS OF THE 8TH INTERNATIONAL CONFERENCE ON ATTOSECOND SCIENCE AND TECHNOLOGY, ATTO 2023 Vol. 300 page： 75 - 82 2024

Publisher：Springer Proceedings in Physics

Upon photoexcitation, molecules break apart, following different dissociation reactions. We can image these dissociation pathways using Coulomb explosion imaging (CEI) and sometimes we can control them using asymmetric laser fields. In the formaldehyde molecule, we can see fragments following the direct, conventional dissociation path, as well as fragments deviating from this minimum energy path. So-called roaming fragments or “roamers” explore the potential energy landscape in a statistical manner and could be directly captured in real-time, despite the signal’s statistical character. This is possible due to the single-molecule sensitivity of CEI and we could show that the onset of roaming occurs actually several orders of magnitude earlier than previously expected. In the polar molecule OCS we go one step further by controlling the fragmentation process using two-color asymmetric laser fields. In addition to expected direct ionization effects, we also see post-ionization contributions, which are usually not visible in heavy polar molecules. We thus show in two different examples that CEI provides the means to extract new, unexpected pathways, which would otherwise remain hidden underneath a strong background.

DOI： 10.1007/978-3-031-47938-0_8

Open Access

Dissociative ionization and Coulomb explosion of CH4 in two-color asymmetric intense laser fields Reviewed International coauthorship

H. Hasegawa, A. Matsuda, T. Morishita, L. B. Madsen, F. Jensen, O. I. Tolstikhin, A. Hishikawa

Physical Chemistry Chemical Physics Vol. 25 ( 37 ) page： 25408 - 25419 2023.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)

Three-dimensional ion momentum imaging reveals that methane in two-color asymmetric intense laser fields has different waveform dependence for atomic and molecular hydrogen ion ejection.

DOI： 10.1039/d3cp02337k

Capturing transient core-to-core resonances in Kr in intense extreme-ultraviolet laser fields by electron-ion coincidence spectroscopy Reviewed

Mizuho Fushitani, Makoto Yamada, Hikaru Fujise, Shigeki Owada, Tadashi Togashi, Kyo Nakajima, Makina Yabashi, Akitaka Matsuda, Yasumasa Hikosaka, Akiyoshi Hishikawa

Physical Review A Vol. 107 ( 2 ) page： L021101 2023.2

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

DOI： 10.1103/PhysRevA.107.L021101

Imaging and Controlling ultrafast Dissociation Dynamics; from conventional to surprising paths

Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevA.107.L021101/fulltext

Orbital effects on tunnel-electron momentum distributions: Ar and H2 studied by electron–ion coincidence momentum imaging Reviewed Open Access

Daimu Ikeya, Hikaru Fujise, Shinnosuke Inaba, Minami Takahashi, Masateru Yamamoto, Takeru Nakamura, Yu Nagao, Akitaka Matsuda, Mizuho Fushitani, Akiyoshi Hishikawa

Journal of Electron Spectroscopy and Related Phenomena Vol. 262 page： 147280 - 147280 2023.1

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

Proceedings of SPIE - The International Society for Optical Engineering Vol. 12419 2023

Publisher：Proceedings of SPIE - The International Society for Optical Engineering

Upon photo-excitation of a molecule it will break apart. We can see fragments following direct, conventional dissociation paths, as well as fragments deviating from this minimum energy path. The latter are called roaming fragments and explore the potential energy landscape in a statistical manner. Dissociating and roaming fragments are directly captured using Coulomb explosion imaging (CEI) and individual pathways are distinguished based on state-of-the-art theory analysis.

DOI： 10.1117/12.2649247

Following ultrafast Roaming Dissociation Dynamics with Coulomb Explosion Imaging

Endo T., Neville S., Lassonde P., Qu C., Fujise H., Fushitani M., Hishikawa A., Houston P., Bowman J., Légaré F., Schuurman M., Ibrahim H.

2023 Conference on Lasers and Electro-Optics, CLEO 2023 2023

Following ultrafast Roaming Dissociation Dynamics with Coulomb Explosion Imaging

Endo T., Neville S., Lassonde P., Qu C., Fujise H., Fushitani M., Hishikawa A., Houston P., Bowman J., Légaré F., Schuurman M., Ibrahim H.

CLEO: Fundamental Science, CLEO:FS 2023 2023

Asymmetric Dissociative Tunneling Ionization of Tetrafluoromethane in ω − 2ω Intense Laser Fields Invited Reviewed Open Access

Hiroka Hasegawa, Tiffany Walmsley, Akitaka Matsuda, Toru Morishita, Lars Bojer Madsen, Frank Jensen, Oleg I. Tolstikhin, Akiyoshi Hishikawa

Frontiers in Chemistry Vol. 10 2022.4

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：Frontiers Media {SA}

<jats:p>Dissociative ionization of tetrafluoromethane (CF<jats:sub>4</jats:sub>) in linearly polarized <jats:italic>ω</jats:italic>-2<jats:italic>ω</jats:italic> ultrashort intense laser fields (1.4 × 10<jats:sup>14</jats:sup> W/cm<jats:sup>2</jats:sup>, 800 and 400 nm) has been investigated by three-dimensional momentum ion imaging. The spatial distribution of <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:math></jats:inline-formula> produced by CF<jats:sub>4</jats:sub> → <jats:inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:math></jats:inline-formula> + F + e<jats:sup>−</jats:sup> exhibited a clear asymmetry with respect to the laser polarization direction. The degree of the asymmetry varies by the relative phase of the <jats:italic>ω</jats:italic> and 2<jats:italic>ω</jats:italic> laser fields, showing that 1) the breaking of the four equivalent C-F bonds can be manipulated by the laser pulse shape and 2) the C-F bond directed along the larger amplitude side of the <jats:italic>ω</jats:italic>-2<jats:italic>ω</jats:italic> electric fields tends to be broken. Weak-field asymptotic theory (WFAT) shows that the tunneling ionization from the 4<jats:italic>t</jats:italic><jats:sub>2</jats:sub> second highest-occupied molecular orbital (HOMO-1) surpasses that from the 1<jats:italic>t</jats:italic><jats:sub>1</jats:sub> HOMO. This predicts the enhancement of the tunneling ionization with electric fields pointing from F to C, in the direction opposite to that observed for the asymmetric fragment ejection. Possible mechanisms involved in the asymmetric dissociative ionization, such as post-ionization interactions, are discussed.</jats:p>

DOI： 10.3389/fchem.2022.857863

Helicity-dependent dissociative tunneling ionization of CF4 in multicycle circularly polarized intense laser fields Reviewed

H. Fujise, M. Uemura, H. Hasegawa, D. Ikeya, A. Matsuda, T. Morishita, L. B. Madsen, F. Jensen, O. I. Tolstikhin, A. Hishikawa

Physical Chemistry Chemical Physics Vol. 24 ( 15 ) page： 8962 - 8969 2022.4

Authorship：Last author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry ({RSC})

Three-dimensional electron–ion coincidence momentum imaging reveals that the dissociative tunneling ionization of tetrafluoromethane (CF4) is sensitive to the helicity of the circularly polarized laser fields.

DOI： 10.1039/d1cp05858d

Post-Ionization Dynamics of the Polar Molecule OCS in Asymmetric Laser Fields Invited Reviewed International coauthorship Open Access

Tomoyuki Endo, Karl Michael Ziems, Martin Richter, Friedrich G. Fröbel, Akiyoshi Hishikawa, Stefanie Gräfe, Fran{\c{c } }ois, L{\'{e } }gar{\'{e, Heide Ibrahim

Frontiers in Chemistry Vol. 10 2022.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers Media {SA}

<jats:p>We have investigated the dissociation mechanisms of the prototypical heavy polar molecule OCS into the two break-up channels of the dication, OCS<jats:sup>2+</jats:sup> → O<jats:sup>+</jats:sup> + CS<jats:sup>+</jats:sup> and OC<jats:sup>+</jats:sup> + S<jats:sup>+</jats:sup>, in phase-locked two-color intense laser fields. The branching ratio of the breaking of the C–O and C–S bonds followed a pronounced 2<jats:italic>π</jats:italic>-oscillation with a modulation depth of 11%, depending on the relative phase of the two-color laser fields. The fragment ejection direction of both break-up channels reflects the anisotropy of the tunneling ionization rate, following a 2<jats:italic>π</jats:italic>-periodicity, as well. The two dissociation pathways in the C–S bond breaking channel show different phase dependencies of the fragment ejection direction, which are assigned to post-ionization dynamics. These observations, resulting from the excitation with asymmetric two-color intense laser fields, supported by state-of-the-art theoretical simulations, reveal the importance of post-ionization population dynamics in addition to tunneling ionization in the molecular fragmentation processes, even for heavy polar molecules.</jats:p>

DOI： 10.3389/fchem.2022.859750

Electronic relaxation and dissociation dynamics in formaldehyde: pump wavelength dependence Reviewed Open Access

Tomoyuki Endo, Simon P. Neville, Philippe Lassonde, Chen Qu, Hikaru Fujise, Mizuho Fushitani, Akiyoshi Hishikawa, Paul L. Houston, Joel M. Bowman, François Légaré, Michael S. Schuurman, Heide Ibrahim

Physical Chemistry Chemical Physics Vol. 24 ( 3 ) page： 1779 - 1786 2022.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry ({RSC})

The effect of the incident UV pump wavelength on the subsequent excited state dynamics, elec- tronic relaxation, and ultimate dissociation of formaldehyde is studied using ﬁrst principles simu- lation and...

DOI： 10.1039/d1cp04264e