Faculty Profiles - HISHIKAWA, Akiyoshi

Papers - HISHIKAWA, Akiyoshi

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Probing the ultrafast nuclear motion in CS22+ in intense laser fields Reviewed

A Hishikawa, M Ueyama, K Yamanouchi

JOURNAL OF CHEMICAL PHYSICS Vol. 122 ( 15 ) 2005.4

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

The temporal evolution of the nuclear wave packet of CS(2)2+ formed in an intense laser field (60 fs, 0.13 PW/cm(2)) is traced in real time by the pump-and-probe technique combined with coincidence momentum imaging of the Coulomb explosion process, CS23+->S+ + C+ + S+. The momentum correlations among the fragment ions obtained as a function of the pump-probe time delay between 133 fs to 3 ps reveal that the nuclear wave packet in CS22+ evolves not only along the anti-symmetric stretching coordinate to yield S+ and CS+ but also along the symmetric stretching coordinate leading to the simultaneous breaking of the two C-S bonds. The contribution from two different electronic states having bent and linear-type geometrical configurations is identified in the wave packet motion along the bending coordinate of CS22+. 2005 American Institute of Physics.

DOI： 10.1063/1.1895745

Web of Science

Probing the ultrafast nuclear motion in CS22+ in intense laser fields Reviewed

Hishikawa, A. and Ueyama, M. and Yamanouchi, K.

Journal of Chemical Physics Vol. 122 ( 15 ) page： 151104 2005

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

DOI： Doi 10.1063/1.1895745

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

Ueyama, M. and Hasegawa, H. and Hishikawa, A. and Yamanouchi, K.

Journal of Chemical Physics Vol. 123 ( 15 ) page： 154305 2005

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

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： Doi 10.1063/1.2032988

Hydrogen migration in acetonitrile in intense laser fields in competition with two-body Coulomb explosion Reviewed

A Hishikawa, H Hasegawa, K Yamanouchi

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Vol. 141 ( 2-3 ) page： 195 - 200 2004.12

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

Two-body Coulomb explosion processes of acetonitrile (CH3CN) and deuterated acetonitrile (CD3CN), CH3CN2+ --> CH3-n+ +HnCN+ and CD3CN2+ --> CD3-n+ +DnCN+ (n = 0-2), in an intense laser field (0.15 pW/cm(2), 70 fs) are investigated by the coincidence momentum imaging method. The comparable yields derived for the three pathways (n = 0-2) shows that the hydrogen atom migration proceeds in competition with the Coulomb explosion. The angular distributions of the fragment ions for n = 0 exhibits a sharp peak along the laser polarization direction while the angular distribution becomes more isotropic as n increases. Based on a least-squares analysis of the fragment anisotropy, the dissociation lifetimes of the doubly charged acetonitrile were determined, from which the time scale of the hydrogen migration as well as the deformation of the C-C-N skeleton prior to the explosion were discussed. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elspec.2004.06.009

Web of Science

Nuclear dynamics on the light-dressed potential energy surface Of CS2 by coincidence momentum imaging Reviewed

A Hishikawa, H Hasegawa, K Yamanouchi

CHEMICAL PHYSICS LETTERS Vol. 388 ( 1-3 ) page： 1 - 6 2004.4

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

The non-sequential three-body Coulomb explosion, CS23+ --> S+ + C+ + S+, in an intense laser field (0.2 PW/cm(2), 60 fs) is studied by the coincidence momentum imaging of the fragment ions. The observed angular distribution of the momentum vectors of the two S+ ions, p(1) (S+) and p(2)(S+), exhibits a peak at an angle as small as theta(12) similar to 140degrees, showing that the nuclear motion is induced along the bending coordinate to a large extent prior to the explosion. On the other hand, the difference between their absolute values, Deltap(12) = \p(1)(S+)\ - \p(2)(S+), has a sharp distribution peaked at Deltap(12) = 0, suggesting that the symmetric stretching motion dominates over the antisymmetric stretching motion in the laser field. Based on the energy dependence of the momentum vector correlation, the characteristic nuclear dynamics of CS2 on the light-dressed potential energy surfaces in an intense laser field is discussed. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2004.01.128

Web of Science

Hydrogen migration in acetonitrile in intense laser fields in competition with two-body Coulomb explosion Reviewed

Hishikawa, A. and Hasegawa, H. and Yamanouchi, K.

Journal of Electron Spectroscopy and Related Phenomena Vol. 141 ( 2-3 ) page： 195-200 2004

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

Hydrogen migration in acetonitrile in intense laser fields studied by coincidence momentum imaging Reviewed

Hishikawa, A. and Hasegawa, H. and Yamanouchi, K.

Physica Scripta Vol. T110 page： 108-111 2004

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

The two-body Coulomb explosion of acetonitrile, CH3CN2+ -> CH3-n+ + HnCN+(n = 0-2), in intense laser fields (0.15 PW/cm(2), 70 fs) is studied by the coincidence momentum imaging technique. It is found that the fragment ions for n 0 are ejected mostly in the direction of the laser polarization vector with < cos(2)theta > = 0.68, where theta is the angle between the fragment recoil direction and the laser polarization vector, while the angle distribution becomes more isotropic as n increases, i.e., < cos(2)theta > = 0.49 for n = 1 and < cos(2)theta > = 0.37 for n = 2. From this characteristic correlation between the anisotropy in the fragment ejection and the hydrogen migration, the Coulomb explosion dynamics competing with the hydrogen atom transfer from the methyl group to the nitrile group is investigated.

Nuclear dynamics on the light-dressed potential energy surface of CS2 by coincidence momentum imaging Reviewed

Hishikawa, A. and Hasegawa, H. and Yamanouchi, K.

Chemical Physics Letters Vol. 388 ( 1-3 ) page： 1-6 2004

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

Hydrogen migration in acetonitrile in intense laser fields studied by coincidence momentum imaging Reviewed

Akiyoshi Hishikawa, Hirokazu Hasegawa, Kaoru Yamanouchi

PHYSICA SCRIPTA Vol. T110 page： 108 - 111 2004

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

DOI： 10.1238/Physica.Topical.110a00108

Web of Science

Hydrogen migration in acetonitrile in intense laser fields studied by coincidence momentum imaging Reviewed

Akiyoshi Hishikawa, Hirokazu Hasegawa, Kaoru Yamanouchi

Physica Scripta T Vol. T110 page： 108 - 111 2004

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

The two-body Coulomb explosion of acetonitrile, CH3CN 2+ → CH3-n+ + HnCN+ (n = 0-2), in intense laser fields (0.15 PW/cm2, 70 fs) is studied by the coincidence momentum imaging technique. It is found that the fragment ions for n = 0 are ejected mostly in the direction of the laser polarization vector with 〈 cos2 θ 〉 = 0.68, where θ is the angle between the fragment recoil direction and the laser polarization vector, while the angle distribution becomes more isotropic as n increases, i.e., 〈 cos2 θ 〉 = 0.49 for n = 1 and 〈 cos2 θ 〉 = 0.37 for n = 2. From this characteristic correlation between the anisotropy in the fragment ejection and the hydrogen migration, the Coulomb explosion dynamics competing with the hydrogen atom transfer from the methyl group to the nitrile group is investigated. © Physica Scripta 2004.

DOI： 10.1238/Physica.Topical.110a00108

Scopus

Sequential three-body Coulomb explosion of CS2 in intense laser fields appearing in momentum correlation map Reviewed

A Hishikawa, H Hasegawa, K Yamanouchi

CHEMICAL PHYSICS LETTERS Vol. 361 ( 3-4 ) page： 245 - 250 2002.7

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

The three-body Coulomb explosion process of CS2 in intense laser fields (60 fs, 0.36 x 10(15) W/cm(2)), CS23+ --> S+ + C+ + S+, is studied by the triple coincidence momentum imaging of the atomic fragment ions. The set of the observed momentum vectors of the fragment ions determined for respective explosion events exhibits a clear trajectory originating from the rotational motion of an intermediate CS2+ ion, formed in a sequential explosion process of CS23+ prior to the complete three-body fragmentation. The contribution of the sequential pathway to the overall three-body explosion process is estimated to be 17(1)%. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0009-2614(02)00880-1

Web of Science

Suppression of decomposition of aniline cation in intense laser fields by cluster formation with ammonia molecules Reviewed

J Watanabe, R Itakura, A Hishikawa, K Yamanouchi

JOURNAL OF CHEMICAL PHYSICS Vol. 116 ( 22 ) page： 9697 - 9702 2002.6

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

Mass-selected aniline cations and [aniline-(NH3)(n)](+) (n=1 and 2) cluster ions are exposed to the femtosecond laser fields (lambdasimilar to395 nm,Isimilar to4x10(15) W/cm(2)) and the nanosecond laser fields (lambda=532 nm,Isimilar to2.7x10(10) W/cm(2)) by using a tandem type time-of-flight mass spectrometer. In the case of the bare aniline cation, the decomposition forming the five-membered ring compound, cyclopentadienyl cation (C5H6+), dominantly proceeds in both the femtosecond and nanosecond laser fields. When one or two ammonia molecules are attached to the aniline cation, the decomposition is significantly suppressed. This suppression was interpreted in terms of an intermolecular energy flow through the hydrogen bonding. (C) 2002 American Institute of Physics.

DOI： 10.1063/1.1475753

Web of Science

Coincidence Imaging of coulomb explosion of CS2 in intense laser fields Reviewed

H Hasegawa, K Doi, A Hishikawa, K Yamanouchi

SCIENCE OF SUPERSTRONG FIELD INTERACTIONS Vol. 634 page： 197 - 198 2002

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

The coincidence imaging technique is applied to direct determination of the momentum vectors of all the fragment ions produced through every event of the Coulomb explosion of a single molecular ion, CS2+ (z = 2 - 4) formed in intense laser fields (0.36 PW/cm(2)). The molecular structure Of CS23+ just before the three-body Coulomb explosion is reconstructed from the measured momentum vectors of the atomic fragment ions. It was confirmed that the skeletal deformation of CS2 is induced to a large extent in intense laser fields.

Web of Science

Coincidence imaging of Coulomb explosion of CS2 in intense laser fields Reviewed

H Hasegawa, A Hishikawa, K Yamanouchi

CHEMICAL PHYSICS LETTERS Vol. 349 ( 1-2 ) page： 57 - 63 2001.11

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

The coincidence imaging technique is applied to direct determination of the momentum vectors of all the fragment ions produced through every event of the Coulomb explosion of a single molecular ion, CS22+ (z = 2-4) formed in intense laser of CS23+ just fields (similar to 60 fs, 0.36 x 10(15) W/cm(2)). The molecular structure I before the Coulomb explosion, CS23+ --> S+ + C+ + S+, is reconstructed from the measured momentum vectors of the fragment ions. The mean C-S bond length of <r > = 2.5 Angstrom and the azimuthally averaged S-C-S bond angle, < gamma > = 145 degrees, thus determined indicate that structural deformation occurs to a large extent in the intense laser fields. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0009-2614(01)01087-9

Web of Science

Real-time probing of alignment and structural deformation of CS2 in intense nanosecond laser fields Reviewed

A Iwasaki, A Hishikawa, K Yamanouchi

CHEMICAL PHYSICS LETTERS Vol. 346 ( 5-6 ) page： 379 - 386 2001.10

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

A time evolution of the alignment and structural deformation processes of neutral CS2 in intense non-resonant nanosecond laser fields (1.9 X 10(12) W/cm(2)) is derived by ionizing CS2 using intense circularly polarized feintosecond laser fields (5.5 x 10(14) W/cm(2)). From the real-time probing of the momentum distribution of the resultant S3+ and C2+ fragment ions produced through the Coulomb explosion induced by the intense fenitosecond laser fields, it is identified that the alignment and the structural deformation proceed simultaneously in the nanosecond laser fields. (C) 2001 Elsevier Science BN. All rights reserved.

DOI： 10.1016/S0009-2614(01)00963-0

Web of Science

Light-induced multiple electronic-state coupling of O-2(+) in intense laser fields Reviewed

A Hishikawa, SL Liu, A Iwasaki, K Yamanouchi

JOURNAL OF CHEMICAL PHYSICS Vol. 114 ( 22 ) page： 9856 - 9862 2001.6

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

The dissociation processes, O-2(+)-->O++O, in intense laser fields (100 fs, similar to 3x10(14) W/cm(2)) are studied at the laser wavelength of 795 and 398 nm on the basis of the momentum imaging maps of the O+ fragment ions. The covariance map measurements are performed with high momentum resolution to assign securely the dissociation pathways. From the anisotropic momentum distribution of O+ with respect to the laser polarization direction, the electronic states of O-2(+) are found to be coupled exclusively through parallel transitions in the course of the dissociation process. The released kinetic energy of O+ for both 795 and 398 nm are interpreted consistently by a sequential coupling model of light-dressed potential curves of O-2(+) in the quartet Pi state manifold. (C) 2001 American Institute of Physics.

DOI： 10.1063/1.1368383

Web of Science

Ionization and fragmentation dynamics of benzene in intense laser fields by tandem mass spectroscopy Reviewed

R Itakura, J Watanabe, A Hishikawa, K Yamanouchi

JOURNAL OF CHEMICAL PHYSICS Vol. 114 ( 13 ) page： 5598 - 5606 2001.4

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

Using a tandem time-of-flight mass spectrometer, benzene cations produced by the resonantly enhanced multiphoton ionization are mass separated and are exposed to intense laser fields (similar to 2x10(16) W/cm(2)) at lambda similar to 790 and 395 nm with the pulse duration of similar to 50 fs. Comparing the yields of the product ions with those obtained from neutral benzene molecules, the ionization and dissociation dynamics of benzene in intense laser fields is investigated. At lambda similar to 790 nm, the formation of parent benzene ions is a dominant process irrespective of the initial charge states, i.e., major products obtained when starting from neutral benzene are benzene cations and dications and those obtained when starting from benzene cation are benzene dications. On the other hand, at lambda similar to 395 nm, the fragmentation processes to produce C4Hi+(i=2-4) and C3Hj+(j=1-3) dominate over further ionization to the benzene dication for both cases starting from neutral benzene and benzene cation, indicating the population trapping occurs by the efficient confinement in the light-dressed mixture of the C and X states of benzene cations assisted by the ultrafast intramolecular decay process. (C) 2001 American Institute of Physics.

DOI： 10.1063/1.1352619

Web of Science

Resonance-state selective photodissociation of OCS (2(1)Sigma(+)): Rotational and vibrational distributions of CO fragments Reviewed

R Itakura, A Hishikawa, K Yamanouchi

JOURNAL OF CHEMICAL PHYSICS Vol. 113 ( 16 ) page： 6598 - 6607 2000.10

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

The rotational and vibrational state distributions of the CO fragments produced through the photodissociation of OCS in the vacuum ultraviolet (VUV) region (150-155 nm), OCS (2 (1)Sigma (+))--> CO (X (1)Sigma (+))+S(S-1), are derived for the three lowest quasi-bound vibrational resonances (upsilon*=0-2) in the 2 (1)Sigma (+) state. The rotational state distributions of the CO fragments in the upsilon (CO)=0 and 1 vibrational states are determined, respectively, by the analysis of the rotational structures in the laser-induced fluorescence (LIF) spectra of the A(1)Pi -X (1)Sigma (+)(0,0) and (1,1) transitions of CO. The rotational temperatures of CO in the upsilon (CO)=0 state are low (similar to 100 K) for all the three resonances, while those in the upsilon (CO)=1 state are substantially higher, i.e., 2210, 940, and 810 K for upsilon*=0, 1, and 2, respectively. The vibrational state distributions of CO are derived from the Doppler spectroscopy of the counterpart S(S-1) fragments. From the analysis of the observed Doppler profiles, it is found for all the three lowest vibrational resonances of OCS that the vibrational distributions are represented well by the Boltzmann-type distribution with a vibrational temperature of around 7000 K. On the basis of these new findings, the energy partitioning in the photodissociation process through these three vibrational resonances in the 2 (1)Sigma (+) state is discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)01740-2].

DOI： 10.1063/1.1310606

Web of Science

Extraction of molecular dynamics in intense laser fields from mass-resolved momentum imaging maps: application to Coulomb explosion of NO Reviewed

A Iwamae, A Hishikawa, K Yamanouchi

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Vol. 33 ( 2 ) page： 223 - 240 2000.1

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

The nuclear dynamics of NO in intense laser fields (similar to 1.4 PW cm(-2)) is studied on the basis of the momentum-scaled time-of-flight spectra and mass-resolved momentum imaging maps of the atomic fragment ions, NP+ and Oq+ (p, q = 1-3), produced from the (p, q) Coulomb explosion pathways of NO, i.e. NO(p+q)+ --> Np+ + Oq+. A procedure to extract nuclear dynamics from the momentum maps is proposed by taking account of the effect of the finite detector size. The resultant nine (p, q) single-pathway components show that (a) the distributions of the N-O internuclear distance of NOz+ just before the Coulomb explosion exhibit significant broadening (similar to 1 Angstrom); (b) the distance at which the corresponding distribution takes a maximum increases from 1.68 to 2.34 Angstrom as z from 2 to 6 with a small amount of suppression at odd z (z = 3, 5); and (c) the atomic fragment ions exhibit narrower angular distributions for a larger total charge z (= p + q) of NOz+.

DOI： 10.1088/0953-4075/33/2/308

Web of Science

Ultrafast structural deformation of polyatomic molecules in intense laser fields Reviewed

K Yamanouchi, A Hishikawa, A Iwamae, SL Liu

PHYSICS OF ELECTRONIC AND ATOMIC COLLISIONS Vol. 500 page： 182 - 191 2000

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

The momentum vector distributions of fragment ions produced through the Coulomb explosion of small molecules such as NO, CO2, NO2, and H2O in intense laser fields (similar to 1 PW/cm(2)) are measured by the mass-resolved momentum imaging (MRMI) technique. For NO, the MRMI maps for a single (p,q) pathway, NO(p+q)+ --> NP+ + Oq+ (p, q = 1 similar to 3), are extracted from the observed MRMI maps on the basis of the momentum matching of the NP+ and Oq+. ion pair. In the MRMI maps for the fragment ions produced from CO2, NO2, and H2O, their ultrafast structural deformation both along the stretching coordinate and along the bending coordinate is identified. The <O-C-O angle distribution of CO2 Spreads significantly (FWHM similar to 40 degrees), and the <O-N-O bond angle of NO2 increases toward a linear configuration within the ultrashort duration of the laser pulse. This type of deformation is also identified for H2O. These structural deformations are most reasonably interpreted as a consequence of the formation of light-dressed potential energy surfaces.

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Papers - HISHIKAWA, Akiyoshi