Faculty Profiles - FUSHITANI, Mizuho

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