Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hayakawa, Sho*; Okita, Taira*; Itakura, Mitsuhiro; Kawabata, Tomoya*; Suzuki, Katsuyuki*
Journal of Materials Science, 54(16), p.11096 - 11110, 2019/08
Times Cited Count：11 Percentile：42.21(Materials Science, Multidisciplinary)Nakanishi, Daiki*; Kawabata, Tomoya*; Doihara, Kohei*; Okita, Taira*; Itakura, Mitsuhiro; Suzuki, Katsuyuki*
Philosophical Magazine, 98(33), p.3034 - 3047, 2018/09
Times Cited Count：10 Percentile：47.84(Materials Science, Multidisciplinary)By using the six sets of interatomic potentials for face-centredcubic metals that differ in the stacking fault energy (SFE) while most of the other material parameters are kept almost identical, we conducted molecular dynamics simulations to evaluate the effects of SFE on the defect formation process through collision cascades. The ratio of glissile SIA clusters tends to decrease with increasing SFE. This is because perfect loops, the edges of which split into two partial dislocations with stacking fault structures between them in most cases, prefer to form at lower SFEs. The enhanced formation of glissile SIA clusters at lower SFEs can also be observed even at increased temperature.
Inukai, Munehiro*; Horike, Satoshi*; Itakura, Tomoya*; Shinozaki, Ryota*; Ogiwara, Naoki*; Umeyama, Daiki*; Nagarker, S.*; Nishiyama, Yusuke*; Malon, M.*; Hayashi, Akari*; et al.
Journal of the American Chemical Society, 138(27), p.8505 - 8511, 2016/07
Times Cited Count：135 Percentile：95.46(Chemistry, Multidisciplinary)Itakura, Ryuji; Hosaka, Koichi*; Yokoyama, Atsushi; Ikuta, Tomoya*; Kannari, Fumihiko*; Yamanouchi, Kaoru*
Progress in Ultrafast Intense Laser Science XI; Springer Series in Chemical Physics, Vol.109, p.23 - 42, 2015/00
We investigate the multichannel dissociative ionization of ethanol in intense laser fields by the photoelectron-photoion coincidence momentum imaging and identify separately the ionization and subsequent electronic excitation in ethanol. From the energy correlation between a photoelectron and a fragment ion, we reveal the amount of the internal energy gained by ethanol cations from the laser field varies depending on the respective ionization and electronic excitation pathways.
Ikuta, Tomoya*; Hosaka, Koichi*; Akagi, Hiroshi; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*; Itakura, Ryuji
Journal of Physics B; Atomic, Molecular and Optical Physics, 44(19), p.191002_1 - 191002_5, 2011/10
Times Cited Count：10 Percentile：47.15(Optics)Ionization and subsequent electronic excitation occurring within the same laser pulse (400 nm, 96 fs, 1.3
18 TW/cm
) are separately investigated by measuring in coincidence an electron and a product ion produced from C
H
OH. We reveal that the nascent population in the electronically excited CHOH
prepared by the ionization decreases as the laser intensity increases, while the subsequent electronic excitation is enhanced through the resonant electronic transitions. Ionization and electronic excitation mechanisms are described based on the electronic state distributions of CHOH.
Itakura, Ryuji; Liu, P.*; Furukawa, Yusuke*; Okino, Tomoya*; Yamanouchi, Kaoru*; Nakano, Hidetoshi*
Journal of Chemical Physics, 127(10), p.104306_1 - 104306_5, 2007/09
Times Cited Count：48 Percentile：84.79(Chemistry, Physical)Coulomb explosion of methanol induced by intense laser pulses with 
t = 7 and 21 fs is investigated by coincidence momentum imaging. When t = 7, the angular distribution of recoil vectors for the direct C-O bond breaking exhibits a peak deflected from the laser polarization direction by 30-45 deg., and the corresponding angular distribution for the migration pathway exhibits almost the same profile. When the laser pulse is stretched to t = 21 fs, the angular distributions for the direct and migration pathways exhibit a broad peak along the laser polarization direction. However, the extent of the anisotropy in the migration pathway is smaller than that in the direct pathway, exhibiting a substantial effect of hydrogen atom migration.
Ikuta, Tomoya; Hosaka, Koichi; Itakura, Ryuji; Akagi, Hiroshi; Yamanouchi, Kaoru*; Kannari, Fumihiko*; Yokoyama, Atsushi
no journal, ,
Recently, using a photoelectron-photoion coincidence momentum imaging apparatus, we found two possible pathways for the dissociative ionization of ethanol in intense NIR laser fields: one pathway is the direct access to the electronically excited states leading to the dissociation, the other is the stepwise excitation through the ionization to the electronic ground state. In this study, we investigate the dissociative ionization in intense UV laser with the same technique and compare the results with those with the NIR pulses.
Itakura, Ryuji; Ikuta, Tomoya*; Hosaka, Koichi*; Akagi, Hiroshi; Yamanouchi, Kaoru*; Yokoyama, Atsushi; Kannari, Fumihiko*
no journal, ,
When ethanol molecules are irradiated with an intense UV pulse (400 nm,100 fs, I = 10 TW/cm
), channel-specific photoelectron momentum images correlated with CHOH, CH
OH, CHOH, and CH show different features, suggesting that different electronic and vibrational state distributions are prepared upon the ionization for the respective product ion channels.
Ikuta, Tomoya; Itakura, Ryuji; Hosaka, Koichi*; Akagi, Hiroshi; Yamanouchi, Kaoru*; Kannari, Fumihiko*; Yokoyama, Atsushi
no journal, ,
When ethanol molecules are irradiated with an intense UV pulse (400 nm, 100 fs, 1533 TW/cm), channel-specific photoelectron momentum images correlated with CHOH, CHOH, CHOH, and CH show different features, suggesting that different electronic and vibrational state distributions are prepared upon the ionization for the respective product ion channels. Basically, the electronic ground state and the first electronically excited state are prepared upon the ionization, and then the subsequent interaction between the ion and the laser field takes place, leading to the respective reaction channels.
Ikuta, Tomoya; Itakura, Ryuji; Hosaka, Koichi*; Akagi, Hiroshi; Yamanouchi, Kaoru*; Kannari, Fumihiko*; Yokoyama, Atsushi
no journal, ,
Dissociative ionization of ethanol is more efficiently induced by intense ultraviolet laser fields than by intense near-infrared laser fields. In this study, our concern are focused on the electronic excitation dynamics in dissociative ionization of ethanol in intense ultraviolet laser fields. Photoelectron-photoion coincidence measurement allows us to understand the dissociation mechanism in terms of electronic excitation.
Ikuta, Tomoya; Itakura, Ryuji; Hosaka, Koichi*; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*
no journal, ,
We investigate the dissociative ionization dynamics of ethanol in two color (UV-NIR) laser fields using photoelectron-photoion coincidence momentum imaging. The details of the ionization dynamics for the respective reaction channels are elucidated. The reaction mechanism in terms of the electronic excitation is discussed.
Itakura, Ryuji; Ikuta, Tomoya*; Hosaka, Koichi*; Akagi, Hiroshi; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*
no journal, ,
Using photoelectron-photoion coincidence technique, we identify two ionization routes of ethanol to the electronic ground state and the electronically excited state of ethanol cation in intense ultraviolet (UV) laser fields (400 nm, 96 fs). The population ratio of the electronically excited state with respect to the electronic ground state of CHOH at the instant of the ionization decreases significantly as the laser intensity increases from 1.3 to 18.1 TW/cm. It is also revealed that the probability of the subsequent electronic excitation of CHOH within the same pulse is enhanced as the laser intensity increases.
Itakura, Ryuji; Ikuta, Tomoya*; Hosaka, Koichi*; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*
no journal, ,
Photoionization dynamics of ethanol in two-color (400 and 800 nm) intense laser fields is investigated using photoelectron-photoion coincidence spectroscopy. It is found that the fragment ion CHOH is formed dominantly through the ionization to the electronically excited state by the 400-nm pulse when a 400-nm pulse and a 800-nm pulse are temporally separated. When a 400-nm pulse is temporally overlapped with a 800-nm pulse, the ionization to the electronically excited state by the 400-nm pulse is significantly suppressed, indicating that the ionization channel to the electronically excited state is closed due to the AC stark up-shift by the 800-nm pulse.
Itakura, Ryuji; Ikuta, Tomoya*; Hosaka, Koichi*; Akagi, Hiroshi; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*
no journal, ,
We investigate dissociative ionization of ethanol induced by intense laser fields using photoelectron-photo ion coincidence momentum imaging. Our attentions are focused on the energy correlation between an electron and a fragment ion produced from an identical ethanol molecule. We reveal that the internal energy gained from laser fields depends on the ionization and fragmentation pathways. We discuss the ionization and dissociation mechanism based on the experimental results depending on the laser characteristics.
Itakura, Ryuji; Ikuta, Tomoya*; Hosaka, Koichi*; Akagi, Hiroshi; Yokoyama, Atsushi; Yamanouchi, Kaoru*; Kannari, Fumihiko*
no journal, ,
We investigate dissociative ionization of ethanol induced by intense laser fields using photoelectron-photo ion coincidence momentum imaging. Our attention is focused on the correlation between (1) photoelectron energy reflecting the state of ethanol cation at ionization and (2) kinetic energy of a fragment ion. From the observed correlation maps, we clarified that the internal energy gained from the laser field strongly depends on the ionization and dissociation pathways.
Okita, Taira*; Itakura, Mitsuhiro; Nakanishi, Daiki*; Kawabata, Tomoya*
no journal, ,
