Faculty Profiles - FUSHITANI, Mizuho

Papers - FUSHITANI, Mizuho

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Wave-packet manipulation of He Rydberg states by a seeded free-electron laser Reviewed Open Access

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

Physical Review Research Vol. 6 ( 4 ) page： 043323 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：American Physical Society (APS)

We report a two-dimensional pump-control-probe spectroscopic study of the dynamics of singly excited He Rydberg-state wave packets with a seeded extreme ultraviolet (XUV) free-electron laser (FEL) source. A pair of coherent XUV pulses, defined by their coarse time separation and relative phase, created and manipulated the wave packets. The He atoms were postionized by infrared (IR) pulses, and the ion yield was measured as a function of XUV phase and IR arrival time. We tagged and sorted the relative phase of the XUV pulse pair on a single-shot basis by fitting each FEL spectrum with a suitable function that accounts for nonidealities of the XUV pulse pairs, associated with the seeding process; more generally, the fit returns the time-dependent electric field of the FEL spectra. The experimental two-dimensional maps of ion yields, measured as a function of IR (probe) delay and of XUV (pump-control) phase, were compared with the solution of the first-order time-dependent Schrödinger equation for this field. Despite the fact that the experimental conditions imply strong excitation, beyond the approximations of first-order perturbation theory, the simulated map satisfactorily reproduces the experimental one for temporally well-separated pulses. We show that by selecting data at appropriate values of pump-control phase, we enhance or suppress the amplitude of chosen wave-packet components consisting of two or more Rydberg states. When the temporal overlap of the pulse pair cannot be neglected, the phase reconstruction is underdetermined, and we provide a simplified comparison between data and simulations.

Published by the American Physical Society 2024

DOI： 10.1103/physrevresearch.6.043323

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

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

Mizuho Fushitani, Yasumasa Hikosaka, Motomichi Tashiro, Akiyoshi Hishikawa

The Journal of Chemical Physics Vol. 160 ( 17 ) page： 174307 2024.5

Authorship：Lead author,　Corresponding 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

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

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 ) page： 104203 2024.3

Authorship：Lead author,　Corresponding author 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 Open Access

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

Springer Proceedings in Physics 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

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

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

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

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

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

Electron-ion Coincidence Imaging of O2 in Intense Laser Fields with Additional Dissociation Pulses

Ikeya D., Matsuda A., Fushitani M., Hishikawa A.

Optics Infobase Conference Papers 2022

Roaming in Formaldehyde – and how to get there

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

Optics Infobase Conference Papers 2022

Time-resolved shot-by-shot photoelectron spectroscopy of autoionizing Xe+ states by EUV–free-electron-laser and near-IR laser pulses Reviewed

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

Physical Review A Vol. 104 ( 2 ) page： 023102 2021.8

Capturing roaming molecular fragments in real time Reviewed 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 Légaré, Heide Ibrahim

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

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

Since the discovery of roaming as an alternative molecular dissociation pathway in formaldehyde (H<sub>2</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.

DOI： 10.1126/science.abc2960

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

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

PHYSICAL REVIEW LETTERS Vol. 124 ( 19 ) 2020.5

Language：Japanese Publisher：Physical Review Letters

Ultrafast multiphoton ionization of Xe in strong extreme ultraviolet free-electron laser (FEL) fields (91 eV, 30 fs, 1.6×1012 W/cm2) has been investigated by multielectron-ion coincidence spectroscopy. The electron spectra recorded in coincidence with Xe4+ show characteristic features associated with two-photon absorption to the 4d-2 double core-hole (DCH) states and subsequent Auger decay. It is found that the pathway via the DCH states, which has eluded clear identification in previous studies, makes a large contribution to the multiple ionization, despite the long FEL pulse duration compared with the lifetime of the 4d core-hole states.

DOI： 10.1103/PhysRevLett.124.193201

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

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

Phys. Rev. Lett. Vol. 124 ( 19 ) page： 193201 2020.5

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

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

Nature Photonics Vol. 10 ( 2 ) page： 102 - + 2016.2

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

EUV and soft X-ray photoelectron spectroscopy of isolated atoms and molecules using single-order laser high-harmonics at 42 eV and 91 eV Reviewed

Fushitani, M., Matsuda, A., Hishikawa, A.

Journal of Electron Spectroscopy and Related Phenomena Vol. 184 ( 11-12 ) page： 561 - 568 2012.1

Applications of pump-probe spectroscopy Reviewed

Mizuho Fushitani

Annual Reports on the Progress of Chemistry - Section C Vol. 104 page： 272 - 297 2008

Publishing type：Research paper (scientific journal)

This review outlines advances that have been made in recent years (2005-2007) in the study of ultrafast dynamics occurring in physical, chemical and biological research fields by using pump-probe techniques. Special emphasis is placed on coherent phenomena in materials and experimental achievements of coherent control of wave packets dynamics. After a brief theoretical description of pump-probe methods, an overview of nuclear and electronic coherences appearing in pump-probe spectroscopy is presented. Some of the highlights include molecular alignments, wave packet interferometry, hydrogen migration, and attosecond electron dynamics. © 2008 The Royal Society of Chemistry.

DOI： 10.1039/b703983m

Coherence and control of molecular dynamics in rare gas matrices

Bargheer, M; Borowski, A; Cohen, A; Fushitani, M; Gerber, RB; Gühr, M; Hamm, P; Ibrahim, H; Kiljunen, T; Korolkov, MV; Kühn, O; Manz, J; Schmidt, B; Schröder, M; Schwentner, N

ANALYSIS AND CONTROL OF ULTRAFAST PHOTOINDUCED REACTIONS Vol. 87 page： 257 - 385 2007

Cage motions induced by electronic and vibrational excitations: Cl-2 in Ar Reviewed

M Fushitani, N Schwentner, M Schroder, O Kuhn

JOURNAL OF CHEMICAL PHYSICS Vol. 124 ( 2 ) 2006.1

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

Femtosecond dynamics of molecular vibrations as well as cage motions in the B <- X transition of Cl-2 in solid Ar have been investigated. We observed molecular vibrational wave-packet motion in experimental pump-probe spectra and an additional oscillation with a 500 fs period which is assigned to the zone-boundary phonon of the Ar crystal. The cage motion is impulsively driven by the B <- X transition due to the expansion of the electronic cloud of the chromophore. To clarify the underlying mechanism, we performed simulations based on the diatomics-in-molecules method which takes into account the different shapes of the Cl-2 electronic wave function in the B and X states as well as the anisotropic interaction with the matrix. The simulation results show that Ar atom motion in the (100) plane is initiated by the electronic transition and that only those Ar atoms oscillate coherently with an similar to 500 fs period which are essentially decoupled from the molecular vibration. Their phase and time evolution are in good agreement with the experimentally observed oscillation, supporting the assignment as a displacive excitation of coherent phonons. (c) 2006 American Institute of Physics.

DOI： 10.1063/1.2147241

Pump-probe spectroscopy with phase-locked pulses in the condensed phase: Decoherence and control of vibrational wavepackets Reviewed

Fushitani, M., Bargheer, M., Gühr, M., Schwentner, N.

Physical Chemistry Chemical Physics Vol. 7 ( 17 ) page： 3143 - 3149 2005

Nuclear spin selection rule in the photochemical reaction of CH<inf>3</inf> in solid parahydrogen Reviewed Open Access

Mizuho Fushitani, Takamasa Momose

Journal of Chemical Physics Vol. 116 ( 24 ) page： 10739 - 10743 2002.6

Language：Japanese Publishing type：Research paper (scientific journal)

Nuclear spin selection rule was investigated in the photochemical reaction of CH3 and solid parahydrogen. Conservation of nuclear spin during the reaction was examined by the intensity distribution of the rotation-vibration spectrum of methane produced by the reaction. The methyl radical CH3 was produced by in situ ultraviolet (UV) photolysis of methyl iodide CH3I embedded in solid parahydrogen. The results showed that the population of each nuclear spin state of methane was different from that of the statistical ratio. This indicated that a nuclear spin selection rule existed in the reaction.

DOI： 10.1063/1.1480003

UV-photolysis of HI•••CO<sub>2</sub> complexes in solid parahydrogen:: Formation of CO and H<sub>2</sub>O

Fushitani, M; Shida, T; Momose, T; Räsänen, M

JOURNAL OF PHYSICAL CHEMISTRY A Vol. 104 ( 16 ) page： 3635 - 3641 2000.4

Distinguishing the XUV-induced Coulomb explosion dynamics of iodobenzene using covariance analysis Reviewed Open Access

Tiffany Walmsley, Felix Allum, James R Harries, Yoshiaki Kumagai, Suzanne Lim, Joseph McManus, Kiyonobu Nagaya, Mathew Britton, Mark Brouard, Philip Bucksbaum, Mizuho Fushitani, Ian Gabalski, Tatsuo Gejo, Paul Hockett, Andrew J Howard, Hiroshi Iwayama, Edwin Kukk, Chow-shing Lam, Russell S Minns, Akinobu Niozu, Sekito Nishimuro, Johannes Niskanen, Shigeki Owada, Weronika O Razmus, Daniel Rolles, James Somper, Kiyoshi Ueda, James Unwin, Shin-ichi Wada, Joanne L Woodhouse, Ruaridh Forbes, Michael Burt, Emily M Warne

Journal of Physics B: Atomic, Molecular and Optical Physics Vol. 57 ( 23 ) page： 235101 - 235101 2024.12

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

Abstract

The primary and secondary fragmentation dynamics of iodobenzene following its ionization at 120 eV were determined using three-dimensional velocity map imaging and covariance analysis. Site-selective iodine 4d ionization was used to populate a range of excited polycationic parent states, which primarily broke apart at the carbon-iodine bond to produce I<sup>+</sup> with phenyl or phenyl-like cations (C<sub> n </sub>H or C<sub> n </sub>H , with n = 1 – 6 and x = 1 – 5). The molecular products were produced with varying degrees of internal excitation and dehydrogenation, leading to stable and unstable outcomes. This further allowed the secondary dynamics of intermediates to be distinguished using native-frame covariance analysis, which isolated these processes in their own centre-of-mass reference frames. The mass resolution of the imaging mass spectrometer used for these measurements enabled the primary and secondary reaction channels to be specified at the level of individual hydrogen atoms, demonstrating the ability of covariance analysis to comprehensively measure the competing fragmentation channels of aryl cations, including those involving intermediate steps.

DOI： 10.1088/1361-6455/ad8799

Other Link： https://iopscience.iop.org/article/10.1088/1361-6455/ad8799/pdf

Time-Resolved Probing of the Iodobenzene C-Band Using XUV-Induced Electron Transfer Dynamics Reviewed International coauthorship International journal Open Access

James Unwin, Weronika O. Razmus, Felix Allum, James R. Harries, Yoshiaki Kumagai, Kiyonobu Nagaya, Mathew Britton, Mark Brouard, Philip Bucksbaum, Mizuho Fushitani, Ian Gabalski, Tatsuo Gejo, Paul Hockett, Andrew J. Howard, Hiroshi Iwayama, Edwin Kukk, Chow-shing Lam, Joseph McManus, Russell S. Minns, Akinobu Niozu, Sekito Nishimuro, Johannes Niskanen, Shigeki Owada, James D. Pickering, Daniel Rolles, James Somper, Kiyoshi Ueda, Shin-ichi Wada, Tiffany Walmsley, Joanne L. Woodhouse, Ruaridh Forbes, Michael Burt, Emily M. Warne

ACS Physical Chemistry Au Vol. 4 ( 6 ) page： 620 - 631 2024.8

Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes <i>via</i> site-selective ionization Reviewed International coauthorship International journal 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

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

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

Language：Japanese 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, electronic relaxation, and ultimate dissociation of formaldehyde is studied using first principles simulation and Coulomb explosion imaging (CEI) experiments.

DOI： 10.1039/d1cp04264e

Time-resolved photoelectron imaging of complex resonances in molecular nitrogen Reviewed Open Access

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

Journal of Chemical Physics Vol. 154 ( 14 ) page： 144305 2021.4

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

We have used the FERMI free-electron laser to perform time-resolved photoelectron imaging experiments on a complex group of resonances near 15.38 eV in the absorption spectrum of molecular nitrogen, N , under jet-cooled conditions. The new data complement and extend the earlier work of Fushitani et al. [Opt. Express 27, 19702-19711 (2019)], who recorded time-resolved photoelectron spectra for this same group of resonances. Time-dependent oscillations are observed in both the photoelectron yields and the photoelectron angular distributions, providing insight into the interactions among the resonant intermediate states. In addition, for most states, we observe an exponential decay of the photoelectron yield that depends on the ionic final state. This observation can be rationalized by the different lifetimes for the intermediate states contributing to a particular ionization channel. Although there are nine resonances within the group, we show that by detecting individual photoelectron final states and their angular dependence, we can identify and differentiate quantum pathways within this complex system. 2

DOI： 10.1063/5.0046577

On the measurement of statistical dynamics using the method of Coulomb explosion imaging

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

AIP Conference Proceedings Vol. 2343 2021.3

Language：Japanese Publishing type：Research paper (international conference proceedings)

Using time-resolved Coulomb explosion imaging (CEI) in an ultraviolet (UV) pump near infrared (NIR) probe experiment, we directly image the different dissociation dynamics in the formaldehyde molecule. Different pathways are distinguished from each other, despite their statistical nature. To extract such dynamics, hidden in a statistical background, calls for an elimination of noise. In our approach, we take advantage of CEI being a quasi-background-free technique.

DOI： 10.1063/5.0047930

Capturing roaming fragments in real time: A molecular road movie

Endo T.

Optics InfoBase Conference Papers 2020.11

Ultrafast Reaction Imaging and Control by Ultrashort Intense Laser Pulses Reviewed Open Access

Akiyoshi Hishikawa, Akitaka Matsuda, Mizuho Fushitani

Bulletin of the Chemical Society of Japan Vol. 93 ( 11 ) page： 1293 - 1304 2020.11

Language：English Publishing type：Research paper (scientific journal) Publisher：The Chemical Society of 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：International Union of Crystallography (IUCr)

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<sup>−1</sup> 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

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

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

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 Open Access

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

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

Journal of Electron Spectroscopy and Related Phenomena Vol. 228 page： 25 - 30 2018.10

強レーザーパルスを用いた量子状態の超高速多光子操作 Invited Reviewed

伏谷瑞穂，菱川明栄

レーザー研究 Vol. 45 page： 493-497 2017.8

Selective bond breaking of CO<inf>2</inf> in phase-locked two-color intense laser fields: Laser field intensity dependence Reviewed Open Access

Endo, T., Fujise, H., Kawachi, Y., Ishihara, A., Matsuda, A., Fushitani, M., Kono, H., Hishikawa, A.

Physical Chemistry Chemical Physics Vol. 19 ( 5 ) page： 3550 - 3556 2017.2

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

Fushitani, M., Hishikawa, A.

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

Imaging Electronic Excitation of NO by Ultrafast Laser Tunneling Ionization Reviewed Open Access

Endo, T., Matsuda, A., Fushitani, M., Yasuike, T., Tolstikhin, O.I., Morishita, T., Hishikawa, A.

Physical Review Letters Vol. 116 ( 16 ) 2016.4

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

Liu, C.-N., Morishita, T., Fushitani, M., Hishikawa, A.

Journal of Physics B: Atomic, Molecular and Optical Physics Vol. 49 ( 3 ) 2016.2

Coincidence momentum imaging of asymmetric Coulomb explosion of CO<inf>2</inf> in phase-locked two-color intense laser fields Reviewed

Endo, T., Fujise, H., Matsuda, A., Fushitani, M., Kono, H., Hishikawa, A.

Journal of Electron Spectroscopy and Related Phenomena Vol. 207 page： 50 - 54 2016.2

22pAE-11 Ultrafast Photoelectron Spectroscopy of N_2 Rydberg Wavepacket Dynamics by EUV Laser High Harmonics

Fushitani M., Toida Y., Legare Francois, Hishikawa A.

Meeting Abstracts of the Physical Society of Japan Vol. 71 page： 819 - 819 2016

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

Other Link： http://orcid.org/0000-0003-1444-8917

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

Other Link： http://orcid.org/0000-0003-1444-8917

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

Other Link： http://orcid.org/0000-0003-1444-8917

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 and A. Hishikawa

Phys. Rev. A Vol. 90 page： 053403 2014.11

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

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

Physical Review A - Atomic, Molecular, and Optical Physics Vol. 90 ( 5 ) 2014.11

Photoelectron-photoion correlation in ultrafast multichannel photoionization of Ar Reviewed

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

Journal of Physics B: Atomic, Molecular and Optical Physics Vol. 47 ( 19 ) page： 195602 2014.10

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

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

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

Optics InfoBase Conference Papers 2014

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

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

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：Japanese 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

Other Link： http://orcid.org/0000-0003-1444-8917

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

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

Physical Review A - Atomic, Molecular, and Optical Physics Vol. 88 ( 6 ) page： 063422 2013.12

Resonances in three-photon double ionization of Ar in intense extreme-ultraviolet free-electron laser fields studied by shot-by-shot photoelectron spectroscopy Reviewed

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

Physical Review A - Atomic, Molecular, and Optical Physics Vol. 88 ( 2 ) page： 023421 2013.8

Time-resolved four-body coulomb explosion imaging of correlated dynamics of hydrogen atoms in acetylene dication Reviewed Open Access

A. Matsuda, M. Fushitani, E. J. Takahashi, A. Hishikawa

EPJ Web of Conferences Vol. 41 2013

Language：English Publishing type：Research paper (international conference proceedings)

The correlated motion of the two deuterium atoms associated with the hydrogen migration and structural deformation to non-planar geometry are identified in acetylene dication by the time-resolved four-body Coulomb explosion imaging. © Owned by the authors, published by EDP Sciences, 2013.

DOI： 10.1051/epjconf/20134102013

Ultrafast nonlinear double excitations of he in intense EUV FEL fields Reviewed Open Access

M. Fushitani, Y. Hikosaka, A. Matsuda, C. N. Liu, T. Morishita, E. Shigemasa, A. Hishikawa

EPJ Web of Conferences Vol. 41 2013

Language：English Publishing type：Research paper (international conference proceedings)

Three-photon double excitation of He in intense EUV FEL fields is studied by the shot-by-shot photoelectron spectroscopy, revealing the enhancement by resonances to the doubly excited states converging to the He+ N=3 level. © Owned by the authors, published by EDP Sciences, 2013.

DOI： 10.1051/epjconf/20134102009

Shot-by-Shot Photoelectron Spectroscopy of Rare Gas Atoms in Ultrashort Intense EUV Free-Electron Laser Fields

Mizuho Fushitani, Yasumasa Hikosaka, Akitaka Matsuda, Eiji Shigemasa, Akiyoshi Hishikawa

Springer Series in Chemical Physics page： 151 - 163 2013

Phase Sensitive Control of Vibronic Guest-Host Interaction: Br-2 in Ar Matrix (vol 113, pg 7439, 2009) Reviewed

Heide Ibrahim, Monika Hejjas, Mizuho Fushitani, Nikolaus Schwentner

JOURNAL OF PHYSICAL CHEMISTRY A Vol. 116 ( 10 ) page： 2598 - 2598 2012.3

Erratum: Phase sensitive control of vibronic guest-host interaction: Br <inf>2</inf> in Ar matrix (Journal of Physical Chemistry A (2009) 113: 26 (7439-7450) DOI: 10.1021/jp900287m) Reviewed

Ibrahim, H., Héjjas, M., Fushitani, M., Schwentner, N.

Journal of Physical Chemistry A Vol. 116 ( 10 ) page： 2598 - 2598 2012

Visualizing correlated dynamics of hydrogen atoms in acetylene dication by time-resolved four-body coulomb explosion imaging Reviewed

Akitaka Matsuda, Mizuho Fushitani, Eiji J. Takahashi, Akiyoshi Hishikawa

Springer Proceedings in Physics Vol. 125 page： 317 - 322 2012

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Springer Science and Business Media, LLC

Ultrafast hydrogenmigration in deuterated acetylene dication (C 2D2+2 ) is studied by time-resolved four-body Coulomb explosion imaging, C2D4+ 2 → D++ C ++ C ++ D +, using a pair of few-cycle intense laser pulses (9 fs, 1.3 × 1014 W/cm 2). Momentum correlation of the D+ ions produced by the full fragmentation process shows that (1) motions of the two deuterium atoms are strongly correlated during the isomerization and (2) the molecular structure deforms to nonplanar geometries. © Springer-Verlag Berlin Heidelberg 2012.

DOI： 10.1007/978-3-642-28948-4_53

Enhanced nonlinear double excitation of he in intense extreme ultraviolet laser fields Reviewed

Hishikawa, A., Fushitani, M., Hikosaka, Y., Matsuda, A., Liu, C.-N., Morishita, T., Shigemasa, E., Nagasono, M., Tono, K., Togashi, T., Ohashi, H., Kimura, H., Senba, Y., Yabashi, M., Ishikawa, T.

Physical Review Letters Vol. 107 ( 24 ) page： 243003 2011.12

A magnetic-bottle multi-electron-ion coincidence spectrometer Reviewed

Matsuda, A., Fushitani, M., Tseng, C.-M., Hikosaka, Y., Eland, J.H.D., Hishikawa, A.

Review of Scientific Instruments Vol. 82 ( 10 ) page： 103105 2011.10

Infrared spectroscopy of rovibrational transitions of methyl radicals (CH<inf>3</inf>, CD<inf>3</inf>) in solid parahydrogen Reviewed

Hoshina, H., Fushitani, M., Momose, T.

Journal of Molecular Spectroscopy Vol. 268 ( 1-2 ) page： 164 - 172 2011.7

Time-resolved EUV photoelectron spectroscopy of dissociating I<inf>2</inf> by laser harmonics at 80 nm Reviewed Open Access

Fushitani, M., Matsuda, A., Hishikawa, A.

Optics Express Vol. 19 ( 10 ) page： 9600 - 9606 2011.5

Visualizing hydrogen atoms migrating in acetylene dication by time-resolved three-body and four-body Coulomb explosion imaging Reviewed

Matsuda, A., Fushitani, M., Takahashi, E.J., Hishikawa, A.

Physical Chemistry Chemical Physics Vol. 13 ( 19 ) page： 8697 - 8704 2011

Multiphoton double ionization of Ar in intense extreme ultraviolet laser fields studied by shot-by-shot photoelectron spectroscopy Reviewed

Hikosaka, Y., Fushitani, M., Matsuda, A., Tseng, C.-M., Hishikawa, A., Shigemasa, E., Nagasono, M., Tono, K., Togashi, T., Ohashi, H., Kimura, H., Senba, Y., Yabashi, M., Ishikawa, T.

Physical Review Letters Vol. 105 ( 13 ) 2010.9

Phase Sensitive Control of Vibronic Guest-Host Interaction: Br-2 in Ar Matrix Reviewed

Heide Ibrahim, Monika Hejjas, Mizuho Fushitani, Nikolaus Schwentner

JOURNAL OF PHYSICAL CHEMISTRY A Vol. 113 ( 26 ) page： 7439 - 7450 2009.7

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

Vibronic progressions are programmed into a pulse shaper which converts them via the inherent Fourier transformation into a train of femtosecond pulses in time domain for chromophore excitation. Double Pulse results agree with phase-sensitive wave packet superposition from a Michelson interferometer which delivers coherence times with high reliability. Spectral resolution of 1 nm and a spacing of around 4 nm within the 20 nm envelope centered at 590 nm delivers a train of seven phase-controlled 40 fs subpulses separated by 250 fs. Combs adjusted to the zero phonon lines (ZPL) and phonon sidebands (PSB) of the B state vibronic progression are reproduced in the chromophore for a coherent subpulse accumulation. B state ZPL wave packet dynamics dominates in pump-probe spectra due to its coherence despite an overwhelming but incoherent A state contribution in absorption. PSB comb accumulation is also phase sensitive and demonstrates coherence within several 100 matrix degrees of freedom in the vicinity.

DOI： 10.1021/jp900287m

Multiple Explosion Pathways of the Deuterated Benzene Trication in 9-fs Intense Laser Fields Reviewed

Akitaka Matsuda, Mizuho Fushitani, Richard A. Thomas, Vitali Zhaunerchyk, Akiyoshi Hishikawa

JOURNAL OF PHYSICAL CHEMISTRY A Vol. 113 ( 11 ) page： 2254 - 2260 2009.3

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

The fragmentation of deuterated benzene (CA) in ultrashort intense laser fields (9 fs, 1 x 10(15) W/cm(2)) is studied by the ion-coincidence momentum imaging technique. Five two-body and eight three-body Coulomb explosion pathways from the trication (C(6)D(6)(3+)), associated with the deprotonation and ring-opening reactions, are identified. It is found from the fragment momentum correlation that all the observed three-body explosion processes proceed sequentially via the two-body Coulomb explosion forming molecular dications, C(m)D(n)(2+), with (m,n) = (6,5), (5,5), (5,4), (4,4), (4,3), and (3,3), which further dissociate into pairs of monocations. The branching ratio of the fragmentation pathways estimated from the number of the observed coincidence events indicates that the fragmentation is nonstatistical.

DOI： 10.1021/jp806466x

Electron-ion coincidence momentum imaging of molecular dissociative ionization in intense laser fields: Application to CS2 Reviewed

Akitaka Matsuda, Mizuho Fushitani, Akiyoshi Hishikawa

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Vol. 169 ( 2-3 ) page： 97 - 101 2009.2

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

An electron-ion coincidence momentum imaging apparatus has been developed and applied to dissociative ionization of CS2 in ultrashort intense laser fields. Photoelectron images of CS2 in 35 fs intense laser fields (2 x 10(13) W/cm(2), 800 nm, linearly polarized) recorded in coincidence with the parent ion, CS2+, show clear concentric ring patterns due to the above-threshold ionization (ATI) process. On the other hand, broad structureless distributions elongated along the direction of the laser polarization are observed in the coincidence electron images for the CS+ and S' fragment ions. The difference in the electron images indicates that the dissociative ionization does not proceed sequentially by the formation and photodissociation of CS2+ in intense laser fields. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elspec.2008.12.004

Time-resolved reaction imaging by intense few-cycle laser pulses and laser high-order harmonics Reviewed

M. Fushitani, A. Matsuda, E. J. Takahashi, A. Hishikawa

Journal of Physics: Conference Series Vol. 185 2009

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Physics Publishing

We discuss two novel approaches to visualize ultrafast dynamics of polyatomic molecules using few-cycle intense laser pulses and the high-order harmonics in the soft X-ray region, respectively. First, we present the real-time Coulomb explosion imaging of ultrafast isomerization of C 2D2 2+ by using intense few-cycle laser pulses (&lt
10 fs, ∼1 PW/cm2, ∼800 nm) to show that the hydrogen migration proceeds recurrently in competition with the molecular dissociation. Secondly, we present a new experimental setup for the real-time inner-core excitation imaging, focusing on the generation and separation of the light source using the 59th order harmonic pulses (∼91 eV) and their characteristics. © 2009 IOP Publishing Ltd.

DOI： 10.1088/1742-6596/185/1/012009

Femtosecond pump-probe 2D optical Kerr effect spectroscopy of molecular hydrogen crystals Reviewed

Falk Königsmann, Mizuho Fushitani, Nina Owschimikow, David T. Anderson, Nikolaus Schwentner

Chemical Physics Letters Vol. 458 ( 4-6 ) page： 303 - 307 2008.6

Publishing type：Research paper (scientific journal)

Femtosecond pump-probe 2D (wavelength and delay) optical Kerr effect (OKE) spectroscopy is used to measure laser induced birefringence in parahydrogen and normal hydrogen crystals at 4.2 K. At the probe center wavelength the OKE signal reveals underdamped sinusoidal modulations at frequencies corresponding to the Raman-active transverse optical phonon mode of solid parahydrogen (36.8 cm-1) and normal hydrogen (38.5 cm-1), respectively. For parahydrogen crystals, at small shifts away from the probe center wavelength the OKE signal displays high frequency oscillations (355 cm-1) which correspond to J = 2 rotons with a 94 fs time period. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2008.04.123

Control of chromophore-to-bath coupling by interferometry: Cl<inf>2</inf> vibrational wave packets in solid Ar Reviewed

M. Fushitani, M. Bargheer, M. Gühr, H. Ibrahim, N. Schwentner

Journal of Physics B: Atomic, Molecular and Optical Physics Vol. 41 ( 7 ) 2008.4

Publishing type：Research paper (scientific journal)

Electronic and vibrational coherences in the B 3Π(0 +u) ← X1Σ+g transition of chlorine (Cl2) molecules doped in an argon matrix are investigated by exciting with a pulse pair whose relative phase is scanned for every time delay step. The spacing and position of the generated spectral comb are controlled by the delay and relative phase of the pulses. The B 3Π(0+u) ← X1Σ +g excitation spectrum shows a progression of zero phonon lines which are decoupled from the lattice and of phonon side bands which originate from a concerted excitation of intramolecular and lattice vibrations. The molecular anharmonicity is compensated for by applying a negative chirp difference of the two pulses, which leads to an asymmetry in the signal around time zero. Absolute phase values are determined from spectral positions in the measured comb patterns. They are used to calculate fringe patterns and to simulate interferograms by a multiplication with the excitation spectrum which are compared with the measured ones in detail. From simulated interferograms of zero phonon lines and phonon side bands, we show that the two contributions can be selected with a large contrast by a time delay of two molecular vibrational periods. © 2008 IOP Publishing Ltd.

DOI： 10.1088/0953-4075/41/7/074013

Nuclear spin conversion of methane in solid parahydrogen Reviewed

Yuki Miyamoto, Mizuho Fushitani, Daisuke Ando, Takamasa Momose

Journal of Chemical Physics Vol. 128 ( 11 ) 2008.3

Publishing type：Research paper (scientific journal)

The nuclear spin conversion of C H4 and C D4 isolated in solid parahydrogen was investigated by high resolution Fourier transform infrared spectroscopy. From the analysis of the temporal changes of rovibrational absorption spectra, the nuclear spin conversion rates associated with the rotational relaxation from the J=1 state to the J=0 state for both species were determined at temperatures between 1 and 6 K. The conversion rate of C D4 was found to be 2-100 times faster than that of C H4 in this temperature range. The faster conversion in C D4 is attributed to the quadrupole interaction of D atoms in C D4, while the conversion in C H4 takes place mainly through the nuclear spin-nuclear spin interaction. The conversion rates depend on crystal temperature strongly above 3.5 K for C H4 and above 2 K for C D4, while the rates were almost constant below these temperatures. The temperature dependence indicates that the one-phonon process is dominant at low temperatures, while two-phonon processes become important at higher temperatures as a cause of the nuclear spin conversion. © 2008 American Institute of Physics.

DOI： 10.1063/1.2889002

Acetylene-vinylidene isomerization in ultrashort intense laser fields studied by triple ion-coincidence momentum imaging Reviewed

Akiyoshi Hishikawa, Akitaka Matsuda, Eiji J. Takahashi, Mizuho Fushitani

JOURNAL OF CHEMICAL PHYSICS Vol. 128 ( 8 ) 2008.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

The isomerization of acetylene via hydrogen migration in intense laser fields (8 X 10 14 W/cm(2)) has been investigated by coincidence momentum imaging of the three-body Coulomb explosion process, C(2)H(2)(3+)-> H(+)C(+)CH(+). When ultrashort (9 fs) laser pulses are used, the angle between the momenta of C(+) and H(+) fragments exhibits a sharp distribution peaked at a small angle (similar to 20 degrees), showing that the hydrogen atom remains near the original carbon site in the acetylene configuration. On the other hand, a significantly broad distribution extending to larger momentum angles (similar to 120 degrees) is observed when the pulse duration is increased to 35 fs, indicating that the ultrafast isomerization to vinylidene is induced in the longer laser pulse, (c) 2008 American Institute of Physics.

DOI： 10.1063/1.2828557

Visualizing recurrently migrating hydrogen in acetylene dication by intense ultrashort laser pulses Reviewed

Akiyoshi Hishikawa, Akitaka Matsuda, Mizuho Fushitani, Eiji J. Takahashi

Physical Review Letters Vol. 99 ( 25 ) 2007.12

Publishing type：Research paper (scientific journal)

We demonstrate the visualization of ultrafast hydrogen migration in deuterated acetylene dication (C2D22+) by employing the pump-probe Coulomb explosion imaging with sub-10-fs intense laser pulses (9 fs, 0.13PW/cm2, 800 nm). It is shown, from the temporal evolution of the momenta of the fragment ions produced by the three-body explosion, C2D23+→D++C++CD+, that the migration proceeds in a recurrent manner: The deuterium atom first shifts from one carbon site to the other in a short time scale (∼90fs) and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation. © 2007 The American Physical Society.

DOI： 10.1103/PhysRevLett.99.258302

In situ photolysis of CD3I in solid orthodeuterium Reviewed

Mizuho Fushitani, Yuki Miyamoto, Hiromichi Hoshina, Takamasa Momose

JOURNAL OF PHYSICAL CHEMISTRY A Vol. 111 ( 49 ) page： 12629 - 12634 2007.12

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

Photochemical reactions of molecules in solid orthodeuterium (o-D-2) have been studied by high-resolution infrared spectroscopy and compared with previous results obtained in solid parahydrogen (p-H-2). Ultraviolet photoplysis of CD3I molecules in solid o-D2 yielded CD3 radicals and iodine atoms efficiently, which indicates a small cage effect in solid o-D2, as in the case of solid p-H2. The Fourier transform infrared spectrum of the nu(3) vibrational band of CD3 showed a rotational structure with additional splitting due to crystal field interactions. The magnetic dipole transition (2P(1/2) (<-) P-2(3/2)) of the I atom isolated in solid o-D-2 was observed together with a strong rotational satellite of deuterium molecules through the electron-roton coupling in solid hydrogen. The tunneling reaction between CD3 and D-2 was not observed in a time scale of a few days, which gives the upper limit of the tunneling,reaction rate of 10(-8) s(-1) at 4.2 K.

DOI： 10.1021/jp0761113

Coherent phonons in the zone boundary region of solid Ar doped with Cl2 Reviewed

Mizuho Fushitani, Nikolaus Schwentner, Maike Schroeder, Oliver Kuehn

ULTRAFAST PHENOMENA XV Vol. 88 page： 618 - + 2007

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

We report on coherent zone-boundary phonons of solid Ar doped with Cl-2 in pump-probe spectra. Comparison with molecular dynamic simulation shows that specific motions of Ar atoms in the (100) plane are responsible for the observed oscillations.

Visualizing recurrently migrating hydrogen by few-cycle intense laser pulses Reviewed

Akiyoshi Hishikawa, Akitaka Matsudal, Mizuho Fushitani, Eiji J. Takahashi

XXV INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC AND ATOMIC COLLISIONS Vol. 88 2007

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

Ultrafast hydrogen migration in deuterated acetylene dication (C(2)D(2)(2+)) is studied by the pump-probe Coulomb explosion imaging with few-cycle intense laser pulses (9 fs, 0.13 PW/cm(2), 800 nm). The temporal evolution of the momenta of the fragment ions produced by the three-body explosion, C(2)D(2)(3+) -> D(+) + C(+) + CD(+), shows that the migration proceeds in a recurrent manner: The deuterium atom first shifts from one carbon site to the other in a short time scale (similar to 90 fs), and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation.

DOI： 10.1088/1742-6596/88/1/012056

Coherent phonons in the zone boundary region of solid Ar doped with Cl2

Mizuho Fushitani, Nikolaus Schwentner, Maike Schroeder, Oliver Kuehn

ULTRAFAST PHENOMENA XV Vol. 88 page： 618 - + 2007

Ultrafast dynamics of halogens in rare gas solids

G{\"u}hr, M., Bargheer, M., Fushitani, M., Kiljunen, T., Schwentner, N.

Physical Chemistry Chemical Physics Vol. 9 ( 7 ) page： 779 - 801 2007

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

We perform time resolved pump-probe spectroscopy on small halogen molecules ClF, Cl-2, Br-2, and I-2 embedded in rare gas solids (RGS). We find that dissociation, angular depolarization, and the decoherence of the molecule is strongly influenced by the cage structure. The well ordered crystalline environment facilitates the modelling of the experimental angular distribution of the molecular axis after the collision with the rare gas cage. The observation of many subsequent vibrational wave packet oscillations allows the construction of anharmonic potentials and indicate a long vibrational coherence time. We control the vibrational wave packet revivals, thereby gaining information about the vibrational decoherence. The coherence times are remarkable larger when compared to the liquid or high pressure gas phase. This fact is attributed to the highly symmetric molecular environment of the RGS. The decoherence and energy relaxation data agree well with a perturbative model for moderate vibrational excitation and follow a classical model in the strong excitation limit. Furthermore, a wave packet interferometry scheme is applied to deduce electronic coherence times. The positions of those cage atoms, excited by the molecular electronic transitions are modulated by long living coherent phonons of the RGS, which we can probe via the molecular charge transfer states.

DOI： 10.1039/b609058n

Correlation between nuclear spin ratio of cyclic C3H2 and chemical evolution in TMC-1 cores

Morisawa Yusuke, Fushitani Mizuho, Kato Yoshiyasu, Hoshina Hiromichi, Simizu Zenzo, Watanabe Shiori, Miyamoto Yuki, Kasai Yasuko, Kawaguchi Kentarou, Momose Takamasa

ASTROPHYSICAL JOURNAL Vol. 642 ( 2 ) page： 954 - 965 2006.5

Correlation between nuclear spin ratio of cyclic C3H2 and chemical evolution in TMC-1 cores Reviewed

Yusuke Morisawa, Mizuho Fushitani, Yoshiyasu Kato, Hiromichi Hoshina, Zenzo Simizu, Shiori Watanabe, Yuki Miyamoto, Yasuko Kasai, Kentarou Kawaguchi, Takamasa Momose

ASTROPHYSICAL JOURNAL Vol. 642 ( 2 ) page： 954 - 965 2006.5

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

The ortho-to-para nuclear spin ratio of cyclopropenylidene ( cyclic C3H2) in TMC-1 cores was investigated using the 45 m radio telescope at Nobeyama Radio Observatory. We have observed four ortho lines (J(KaKc) = 2(12) - 1(01), 3(12) - 3(03), 3(21) - 3(12), and 3(30) - 3(21)) and four para lines (J(KaKc) 2(02) - 1(11), 2(11) - 2(02), 2(20) - 2(11), and 3(22) - 3(13)) of cyclic C3H2 in six cores in TMC-1. A statistical equilibrium analysis of the observed intensities revealed apparent correlation between the ortho-to-para ratio of cyclic C3H2 and chemical evolution of the molecular cloud; the ortho-to-para ratio in younger cores is less than 2, while that in older cores is close to the statistical ratio of 3. A simple chemical model calculation indicates that the correlation is ascribed to the conservation of nuclear spin angular momenta in chemical reactions relevant to the production, destruction, and reproduction of cyclic C3H2. Since cyclic C3H2 has been observed in a variety of sources, the ortho-to-para ratio of cyclic C3H2 may be a useful probe of chemical evolution of molecular clouds.

DOI： 10.1086/501041

Chemical reactions in quantum crystals Reviewed

T Momose, M Fushitani, H Hoshina

INTERNATIONAL REVIEWS IN PHYSICAL CHEMISTRY Vol. 24 ( 3-4 ) page： 533 - 552 2005.12

Language：English Publisher：TAYLOR & FRANCIS LTD

Solid parahydrogen, known as a quantum crystal, is a novel matrix for the study of physical and chemical processes of molecules at low temperatures by high-resolution infrared spectroscopy. Ro-vibrational motion of molecules embedded in solid parahydrogen is well quantized on account of the weak interaction in the crystal. In addition, molecules are almost free from the cage effect because of the softness of the quantum crystal, so that a variety of chemical reactions could be observed for molecules in solid parahydrogen at liquid He temperatures. In this article, we survey our recent studies on photodissociation of methyl radicals and subsequent reactions in solid parahydrogen, and discuss ( 1) the nuclear spin selection rule in chemical reactions and ( 2) pure tunnelling reactions obtained from the analysis of the present system.

DOI： 10.1080/01442350500444107

Search for CCH-, NCO-, and NCS- Negative Ions in Molecular Clouds Reviewed Open Access

Y Morisawa, H Hoshina, Y Kato, Z Simizu, S Kuma, N Sogoshi, M Fushitani, S Watanabe, Y Miyamoto, T Momose, Y Kasai, K Kawaguchi

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN Vol. 57 ( 2 ) page： 325 - 334 2005.4

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Despite several suggestions concerning the existence of negatively charged molecules and negative atomic ions in molecular clouds, few attempts have been made to search for negative ions in molecular clouds. In the present study, we extensively searched for three negative molecular ions (CCH-, NCO-, and NCS-) in a dark cloud, L134N, using the Nobeyama 45-m radio telescope. The three negative ions are molecules whose rotational constants have been reported based on laboratory experiments. After a long accumulation, a trace amount of an unidentified emission line was detected at a frequency close to the theoretical prediction of the J = 1-0 transition of CCH-. If this unidentified line is attributable to CCH-, the observed emission intensity would provide an estimation of the column density of CCH- in L134N to be 1.0 x 10(11) cm(-2), which corresponds to a fractional abundance of 5 x 10(-12) relative to hydrogen. However, our recent observation using the IRAM 30-m telescope did not reproduce the J = 1-0 signal, nor detect any trace of the J = 2-1 transition. Thus, the identification of CCH- in L134N is not yet confirmed. As for other ions, signals of neither NCO- nor NCS- were detected in L134N. Although we also searched for the three negative ions in a translucent cloud, CB228, and a star-forming region, SgrB2, no signals were detected. The upper limit abundances of the ions in these clouds are discussed limit abundances of the ions in these clouds are discussed.

DOI： 10.1093/pasj/57.2.325

Other Link： http://orcid.org/0000-0002-0567-6881

Wavepacket interferometry and wavepacket dynamics in condensed phase Reviewed

M Bargheer, M Fushitani, M Guhr, N Schwentner

ULTRAFAST PHENOMENA XIV Vol. 79 page： 304 - 306 2005

Wavepacket interferometry and wavepacket dynamics in condensed phase

M Bargheer, M Fushitani, M Guhr, N Schwentner

ULTRAFAST PHENOMENA XIV Vol. 79 page： 304 - 306 2005

Tunneling chemical reactions in solid parahydrogen: Direct measurement of the rate constants of R+H-2 -> RH+H (R=CD3,CD2H,CDH2,CH3) at 5 K Reviewed Open Access

H Hoshina, M Fushitani, T Momose, T Shida

JOURNAL OF CHEMICAL PHYSICS Vol. 120 ( 8 ) page： 3706 - 3715 2004.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

Tunneling chemical reactions between deuterated methyl radicals and the hydrogen molecule in a parahydrogen crystal have been studied by Fourier transform infrared spectroscopy. The tunneling rates of the reactions R+H-2-->RH+H (R=CD3,CD2H,CDH2) in the vibrational ground state were determined directly from the temporal change in the intensity of the rovibrational absorption bands of the reactants and products in each reaction in solid parahydrogen observed at 5 K. The tunneling rate of each reaction was found to differ definitely depending upon the degree of deuteration in the methyl radicals. The tunneling rates were determined to be 3.3x10(-6) s(-1), 2.0x10(-6) s(-1), and 1.0x10(-6) s(-1) for the systems of CD3, CD2H, and CDH2, respectively. Conversely, the tunneling reaction between a CH3 radical and the hydrogen molecule did not proceed within a week's time. The upper limit of the tunneling rate of the reaction of the CH3 radical was estimated to be 8x10(-8) s(-1). (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1642582

High-resolution spectroscopy and the analysis of ro-vibrational transitions of molecules in solid parahydrogen Reviewed

T Momose, H Hoshina, M Fushitani, H Katsuki

VIBRATIONAL SPECTROSCOPY Vol. 34 ( 1 ) page： 95 - 108 2004.1

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

Solid parahydrogen provides a novel matrix for isolation spectroscopy of atoms and molecules. Ro-vibrational motion of molecules embedded in solid parahydrogen is well quantized on account of the weak interactions in the crystal and of the softness of the crystal being characteristic of quantum crystals. Most of the observed spectral linewidths are one or two orders of magnitude sharper than those observed in conventional rare gas matrices. The sharp linewidths make the parahydrogen crystal an excellent matrix for the study of ro-vibrational states and dynamics of dopant molecules in the condensed phase by high-resolution spectroscopy. In this article, we have summarized the most fundamental part of our study, that is, the theory of ro-vibrational states of dopant molecules in the crystal, which is necessary for the quantitative analysis of high-resolution infrared spectra. We also discuss what we have learned from the analysis of high-resolution infrared spectra in solid parahydrogen. These include perturbations to rotational motion of dopant molecules, reduction of rotational constants, vibrational dephasing and relaxation. Outstanding questions to be solved are also discussed herein. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.vibspec.2003.06.001

A study on diffusion of H atoms in solid parahydrogen Reviewed Open Access

M. Fushitani, T. Momose

Low Temperature Physics Vol. 29 ( 9-10 ) page： 740 - 743 2003.9

Publishing type：Research paper (scientific journal)

Diffusion of hydrogen atoms in solid parahydrogen was investigated using high-resolution infrared spectroscopy. Hydrogen atoms were produced as by-products of a photoinduced reaction of nitric oxides embedded in solid parahydrogen. The diffusion of the hydrogen atoms is mainly terminated by the reaction H+NO→HNO. The diffusion rate determined from the increase of the intensity of rotation-vibration transitions of HNO molecules was found to be two orders of magnitude larger than that determined by the self-recombination reaction of H+H→H2 in pure parahydrogen crystals. © 2003 American Institute of Physics.

DOI： 10.1063/1.1614182

Quantum property of solid hydrogen as revealed by high-resolution laser spectroscopy Reviewed Open Access

H. Katsuki, M. Fushitani, T. Momose

Low Temperature Physics Vol. 29 ( 9-10 ) page： 832 - 837 2003.9

Publishing type：Research paper (scientific journal)

Pure vibrational overtone transitions of solid parahydrogen are studied using high-resolution laser spectroscopy. Extremely narrow spectral linewidth (∼20MHz) allows us to observe rich spectral structure that originates in subtle intermolecular interactions in the crystal. It is found that anisotropy of the distribution of zero-point lattice vibration of hydrogen molecules perturbs the energy levels of the vibrationally excited states significantly. A large amplitude of zero-point lattice vibration, an intrinsic propoerty of quantum solids, is directly observed from the present high-resolution spectroscopy. The first observation of a pure vibrational overtone transition of solid orthodeuterium is also discussed. © 2003 American Institute of Physics.

DOI： 10.1063/1.1619353

Stimulated stokes downconversion in liquid and solid parahydrogen Reviewed

B. J. McCall, A. J. Huneycutt, R. J. Saykally, C. M. Lindsay, T. Oka, M. Fushitani, Y. Miyamoto, T. Momose

Applied Physics Letters Vol. 82 ( 9 ) page： 1350 - 1352 2003.3

Publishing type：Research paper (scientific journal)

The results of investigations into the suitability of condensed-phase parahydrogen as a Raman-shifting medium for infrared cavity ringdown laser absorption spectroscopy were reported. The conversion of ∼10-ns pulses of 532-nm radiation into first-, second-, and third-order vibrational Stokes radiation in bulk liquid and solid parahydrogen after a single 11-cm pass was observed. It was found that the liquid H2 yields more efficient conversion than solid H2 with certain focal geometries, and in case of the solid, a collimated or loosely focused pump geometry was more efficient than a tight focus.

DOI： 10.1063/1.1556560

Generation of infrared radiation by stimulated Raman scattering in para-hydrogen crystal at 5 K Reviewed

Mizuho Fushitani, Susumu Kuma, Yuuki Miyamoto, Hiroyuki Katsuki, Tomonari Wakabayashi, Takamasa Momose, Andrey F. Vilesov

Optics Letters Vol. 28 ( 1 ) page： 37 - 39 2003.1

Publishing type：Research paper (scientific journal)

We report the preliminary results of our experiments with stimulated Raman scattering in para-hydrogen crystal aimed at developing a continuously tunable laboratory laser source of mid-infrared radiation. With laser pulses at 532 nm, a conversion efficieney for the first Stokes beam of as much as 20% in the forward direction was observed through a single-pass, 5-cm-long crystal. Generation of mid-infrared pulses at 4.5 μm was achieved by use of the output of a near-infrared pulsed laser (1.6 μm, 3 ns), and an absorption spectrum of gaseous CD4 molecules was successfully recorded. These results suggest use of the solid para-hydrogen Raman shifter as a promising light source for mid-infrared spectroscopy. © 2003 Optical Society of America.

DOI： 10.1364/OL.28.000037

Generation of infrared radiation by stimulated Raman scattering in para-hydrogen crystal at 5 K

Fushitani M, Kuma S, Miyamoto Y, Katsuki H, Wakabayashi T, Momose T, Vilesov AF

OPTICS LETTERS Vol. 28 ( 1 ) page： 37 - 39 2003.1

The P-2(1/2)<- P-2(3/2) transition of the iodine atom photoproduced from alkyl iodides in solid parahydrogen: detection of new absorptions

Fushitani M, Momose T, Shida T

CHEMICAL PHYSICS LETTERS Vol. 356 ( 3-4 ) page： 375 - 382 2002.4

The <sup>2</sup>P<inf>1/2</inf> ← <sup>2</sup>P<inf>3/2</inf> transition of the iodine atom photoproduced from alkyl iodides in solid parahydrogen: Detection of new absorptions Reviewed

Mizuho Fushitani, Takamasa Momose, Tadamasa Shida

Chemical Physics Letters Vol. 356 ( 3-4 ) page： 375 - 382 2002.4

Publishing type：Research paper (scientific journal)

Alkyl iodides were photolyzed in solid parahydrogen at about 5 K. The first photolysis with 253.7 nm photons yielded two products by reactions, RI + hv (253.7 nm) → Rfree + ·Ifree and (R·-·I), the latter being a complex between the radical R· and the iodine atom ·I. Subsequent photolysis with 193 nm photons activated the radical moiety in both products to induce a reaction, R· + H2 + hv (193 nm) → RH + ·H, which gave the products RHfree and (RH-·I). The radical R· and the alkane RH were characterized by the mid-IR absorption while the iodine atoms in ·Ifree and (R·-·I) and (RH-·I) were identified by the near IR absorption of the magnetic dipole transition of the atom. © 2002 Published by Elsevier Science B.V.

DOI： 10.1016/S0009-2614(02)00354-8

UV-photolysis of HI⋯CO<inf>2</inf> complexes in solid parahydrogen: Formation of CO and H<inf>2</inf>O Reviewed

Mizuho Fushitani, Tadamasa Shida, Takamasa Momose, Markku Räsänen

Journal of Physical Chemistry A Vol. 104 ( 16 ) page： 3635 - 3641 2000.4

Publishing type：Research paper (scientific journal)

The photochemistry of (HI)m⋯(CO2)n (m, n = 1,2, ...) complexes trapped in solid parahydrogen was studied by Fourier transform infrared absorption spectroscopy. Photolysis of the HI in the HI⋯(CO2)n complexes results in the generation of carbon monoxide and water molecules along with iodine atoms. Analysis of the observed spectra leads to the conclusion that the energetic hydrogen atom produced by the photolysis of HI initiates the reaction with one of the CCh molecules in the complexes as H + CO2 → OH + CO, which is followed by the secondary reaction of OH radicals with the matrix hydrogen as OH + H2 → H2O + H. These four-atom reactions are of practical importance in combustion processes as well as of theoretical importance in fundamental chemical dynamics. The result of the present study shows the usefulness of the parahydrogen matrix for fundamental study of photochemistry with the use of weakly bound complexes. © 2000 American Chemical Society.

DOI： 10.1021/jp9938462

Photoinduced reactions of methyl radical in solid parahydrogen

Fushitani M, Sogoshi N, Wakabayashi T, Momose T, Shida T

JOURNAL OF CHEMICAL PHYSICS Vol. 109 ( 15 ) page： 6346 - 6350 1998.10

Photoinduced reactions of methyl radical in solid parahydrogen Reviewed

Mizuho Fushitani, Norihito Sogoshi, Tomonari Wakabayashi, Takamasa Momose, Tadamasa Shida

Journal of Chemical Physics Vol. 109 ( 15 ) page： 6346 - 6350 1998

Publishing type：Research paper (scientific journal)

Photolysis of methyl iodide in solid parahydrogen (p-H2) at about 5 K is studied with ultraviolet light at 253.7 and 184.9 nm. It is found that the light at 253.7 nm produces only methyl radical, whereas the light at 184.9 nm yields both methyl radical and methane. The mechanism of the formation of the photoproducts is elucidated by analyzing the temporal behavior of the observed vibrational absorption. It is concluded that methyl radical in the ground state does not react with p-H2 molecules appreciably but that the radical in the electronic excited state of B̃(2A1′), accessible by reabsorption of 184.9 nm photons by the radical, decomposes to a singlet methylene CH2 ã(1A1) and a hydrogen atom (2S) and that the singlet methylene reacts with a p-H2 molecule to give methane. © 1998 American Institute of Physics.

DOI： 10.1063/1.477276

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