Papers - HISHIKAWA, Akiyoshi

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

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

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

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Electron-ion coincidence momentum imaging of molecular dissociative ionization in intense laser fields: Application to CS(2) Reviewed

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

Journal of Electron Spectroscopy and Related Phenomena   Vol. 169 ( 2-3 ) page： 97-101   2009

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An electron-ion coincidence momentum imaging apparatus has been developed and applied to dissociative ionization of CS(2) in ultrashort intense laser fields. Photoelectron images of CS(2) in 35 fs intense laser fields (2 x 10(13) W/cm(2), 800 nm, linearly polarized) recorded in coincidence with the parent ion, CS(2)(+), 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 CS(2)(+) in intense laser fields. (C) 2008 Elsevier B.V. All rights reserved.

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

Matsuda, A. and Fushitani, M. and Thomas, R. A. and Zhaunerchyk, V. and Hishikawa, A.

Journal of Physical Chemistry A   Vol. 113 ( 11 ) page： 2254-2260   2009

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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.

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

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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

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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

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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

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

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

Journal of Chemical Physics   Vol. 128 ( 8 ) page： 084302   2008

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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： 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

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We demonstrate the visualization of ultrafast hydrogen migration in deuterated acetylene dication (C(2)D(2)(2+)) by employing the pump-probe Coulomb explosion imaging with sub-10-fs intense laser pulses (9 fs, 0.13 PW/cm(2), 800 nm). It is shown, from the temporal evolution of the momenta of the fragment ions produced by the three-body explosion, C(2)D(2)(3+) -> 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 (similar to 90 fs) and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation.

DOI： 10.1103/PhysRevLett.99.258302

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Dalitz plot analysis of Coulomb exploding O-3 in ultrashort intense laser fields Reviewed

Akitaka Matsuda, Eiji J. Takahashi, Akiyoshi Hishikawa

JOURNAL OF CHEMICAL PHYSICS   Vol. 127 ( 11 )   2007.9

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The three-body Coulomb explosion of O-3, O-3(3+)-> O++O++O+, in ultrashort intense laser fields (2x10(15) W/cm(2)) is studied with two different pulse durations (9 and 40 fs) by the coincidence momentum imaging method. In addition to a decrease in the total kinetic energy release, a broadening in the Dalitz plot distribution [Philos. Mag. 44, 1068 (1953)] is observed when the pulse duration is increased from 9 to 40 fs. The analysis based on a simple Coulomb explosion model shows that the geometrical structure of O-3 remains almost unchanged during the interaction with the few-cycle intense laser fields, while a significant structural deformation along all the three vibrational coordinates, including the antisymmetric stretching coordinate, is identified in the 40 fs intense laser fields. The observed nuclear dynamics are discussed in terms of the population transfer to the excited states of O-3. (c) 2007 American Institute of Physics.

DOI： 10.1063/1.2766718

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Electronic and nuclear responses of fixed-in-space H2S to ultrashort intense laser fields (vol 97, art no 243002, 2006) Reviewed

Akiyoshi Hishikawa, Eiji J. Takahashi, Akitaka Matsuda

PHYSICAL REVIEW LETTERS   Vol. 98 ( 1 )   2007.1

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DOI： 10.1103/PhysRevLett.98.019901

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

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

Physical Review Letters   Vol. 99 ( 25 ) page： 258302   2007

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We demonstrate the visualization of ultrafast hydrogen migration in deuterated acetylene dication (C(2)D(2)(2+)) by employing the pump-probe Coulomb explosion imaging with sub-10-fs intense laser pulses (9 fs, 0.13 PW/cm(2), 800 nm). It is shown, from the temporal evolution of the momenta of the fragment ions produced by the three-body explosion, C(2)D(2)(3+) -> 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 (similar to 90 fs) and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation.

DOI： Doi 10.1103/Physrevlett.99.258302

Dalitz plot analysis of Coulomb exploding O-3 in ultrashort intense laser fields Reviewed

Matsuda, A. and Takahashi, E. J. and Hishikawa, A.

Journal of Chemical Physics   Vol. 127 ( 11 ) page： 114318   2007

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The three-body Coulomb explosion of O-3, O-3(3+)-> O++O++O+, in ultrashort intense laser fields (2x10(15) W/cm(2)) is studied with two different pulse durations (9 and 40 fs) by the coincidence momentum imaging method. In addition to a decrease in the total kinetic energy release, a broadening in the Dalitz plot distribution [Philos. Mag. 44, 1068 (1953)] is observed when the pulse duration is increased from 9 to 40 fs. The analysis based on a simple Coulomb explosion model shows that the geometrical structure of O-3 remains almost unchanged during the interaction with the few-cycle intense laser fields, while a significant structural deformation along all the three vibrational coordinates, including the antisymmetric stretching coordinate, is identified in the 40 fs intense laser fields. The observed nuclear dynamics are discussed in terms of the population transfer to the excited states of O-3. (c) 2007 American Institute of Physics.

DOI： Doi 10.1063/1.2766718

Coincidence momentum imaging of two- and three-body Coulomb explosion of ethanol in intense laser fields Reviewed

Ryuji Itakura, Takahiro Teramoto, Akiyoshi Hishikawa, Kaoru Yamanouchi

ULTRAFAST OPTICS V   Vol. 132   page： 375 - +   2007

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

Dissociative ionization of ethanol in intense laser fields is investigated by the coincidence momentum imaging method. Two-body Coulomb explosion channels with the hydrogen migration are identified in addition to a three-body Coulomb explosion channel. On the basis of the momentum vector distributions of the fragment ions, the dissociative ionization dynamics is discussed.

DOI： 10.1007/978-0-387-49119-6_49

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Coulomb explosion imaging of molecular dynamics in intense laser fields Reviewed

Akiyoshi Hishikawa, Kaoru Yamanouchi

Springer Series in Chemical Physics   Vol. 85   page： 1 - 24   2007

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The nuclear dynamics of polyatomic molecules in intense laser fields (∼1 PW/cm2) is studied through the momentum imaging of the fragment ions produced through Coulomb explosion. Characteristic nuclear dynamics that occur on the multidimensional potential energy surfaces in intense laser fields, such as sequential and concerted bond-breaking and hydrogen migration, are elucidated from momentum correlations among the fragment ions. © 2007 Springer-Verlag.

DOI： 10.1007/978-3-540-38156-3-1

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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   page： 12056   2007

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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

Web of Science

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

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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

Web of Science

Electronic and nuclear responses of fixed-in-space H2S to ultrashort intense laser fields Reviewed

Akiyoshi Hishikawa, Eiji J. Takahashi, Akitaka Matsuda

PHYSICAL REVIEW LETTERS   Vol. 97 ( 24 )   2006.12

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

The Coulomb explosion dynamics of H2S, H2S3+-> H++S++H+, in ultrashort intense laser fields (12 fs, similar to 2x10(14) W/cm(2)) is studied by the coincidence momentum imaging of the three fragment ions. Different electronic and nuclear responses are identified depending on the direction of laser polarization epsilon in the molecular frame. The dependence can be interpreted in terms of the electronic and bonding characters of charge transfer states of H2S coupled to the electronic ground state.

DOI： 10.1103/PhysRevLett.97.243002

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Dissociative ATI of H-2 and D-2 in intense soft x-ray laser fields Reviewed

K Hoshina, A Hishikawa, K Kato, T Sako, K Yamanouchi, EJ Takahashi, Y Nabekawa, K Midorikawa

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS   Vol. 39 ( 4 ) page： 813 - 829   2006.2

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The dissociative photoionization processes of H-2 and D-2 in an intense, short-pulsed soft x-ray field (lambda = 29.6 nm, 3 x 10(12) W CM-2, 15 fs) generated as the 27th high-order harmonic of a Ti:sapphire laser is investigated for the first time by time-of-flight mass spectrometry. The ejected H+ fragment ions from H2 are distributed in the kinetic energy range of 3-20 eV peaked at 10.0 eV, and the yield exhibits a nonlinear dependence of the order of 1.7(l) on the light field intensity of the 27th harmonic. Similarly, the D+ fragment ions from D-2 are distributed in the 3-20 eV range peaked at 10.3 eV, and the yield exhibits a nonlinear dependence of the order of 1.6 +/- 0.2. The kinetic energy distributions of H+ and D+ and the nonlinearity in their yields are interpreted well by the two coexisting ionization processes: (i) one-photon dissociative ionization and (ii) dissociative two-photon above-threshold-ionization (ATI) mainly into the repulsive 2p pi(u) state.

DOI： 10.1088/0953-4075/39/4/007

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Electronic and nuclear responses of fixed-in-space H2S to ultrashort intense laser fields Reviewed

Hishikawa, A. and Takahashi, E. J. and Matsuda, A.

Physical Review Letters   Vol. 97 ( 24 ) page： 243002   2006

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The Coulomb explosion dynamics of H2S, H2S3+-> H++S++H+, in ultrashort intense laser fields (12 fs, similar to 2x10(14) W/cm(2)) is studied by the coincidence momentum imaging of the three fragment ions. Different electronic and nuclear responses are identified depending on the direction of laser polarization epsilon in the molecular frame. The dependence can be interpreted in terms of the electronic and bonding characters of charge transfer states of H2S coupled to the electronic ground state.

DOI： Doi 10.1103/Physrevlett.97.243002

Dissociative ATI of H-2 and D-2 in intense soft x-ray laser fields Reviewed

Hoshina, K. and Hishikawa, A. and Kato, K. and Sako, T. and Yamanouchi, K. and Takahashi, E. J. and Nabekawa, Y. and Midorikawa, K.

Journal of Physics B-Atomic Molecular and Optical Physics   Vol. 39 ( 4 ) page： 813-829   2006

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The dissociative photoionization processes of H-2 and D-2 in an intense, short-pulsed soft x-ray field (lambda = 29.6 nm, 3 x 10(12) W CM-2, 15 fs) generated as the 27th high-order harmonic of a Ti:sapphire laser is investigated for the first time by time-of-flight mass spectrometry. The ejected H+ fragment ions from H2 are distributed in the kinetic energy range of 3-20 eV peaked at 10.0 eV, and the yield exhibits a nonlinear dependence of the order of 1.7(l) on the light field intensity of the 27th harmonic. Similarly, the D+ fragment ions from D-2 are distributed in the 3-20 eV range peaked at 10.3 eV, and the yield exhibits a nonlinear dependence of the order of 1.6 +/- 0.2. The kinetic energy distributions of H+ and D+ and the nonlinearity in their yields are interpreted well by the two coexisting ionization processes: (i) one-photon dissociative ionization and (ii) dissociative two-photon above-threshold-ionization (ATI) mainly into the repulsive 2p pi(u) state.

Concerted and sequential Coulomb explosion processes of N2O in intense laser fields by coincidence momentum imaging Reviewed

M Ueyama, H Hasegawa, A Hishikawa, K Yamanouchi

JOURNAL OF CHEMICAL PHYSICS   Vol. 123 ( 15 )   2005.10

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

The Coulomb explosion dynamics of N2O in intense laser fields (800 nm, 60 fs, similar to 0.16 PW/cm(2)) is studied by the coincidence momentum imaging method. From the momentum correlation maps obtained for the three-body fragmentation pathway, N2O3+-> N++N++O+, the ultrafast structural deformation dynamics of N2O prior to the Coulomb explosion is extracted. It is revealed that the internuclear N-N and N-O distances stretch simultaneously as the bond angle > N-N-O decreases. In addition, two curved thin distributions are identified in the momentum correlation maps, and are interpreted well as those originating from the sequential dissociation pathway, N2O3+-> N++NO2+-> N++N++O+. (c) 2005 American Institute of Physics.

DOI： 10.1063/1.2032988

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