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Itakura, Ryuji
no journal, ,
In the present study, we observe the photoelectron momentum images for each reaction pathway of ethanol in intense laser fields. A photoelectron is detected in coincidence with a mass-selected product ion. Although a lot of reaction channels are opened in intense laser induced ionization, we can securely obtain 3D photoelectron momentum images correlated to a specific product ion. The intensity dependence, pulse-length dependence, and detailed structure of the photoelectron images are examined quantitatively for gaining the further insight into the electronic dynamics induced by intense laser fields.
Hosaka, Koichi; Itakura, Ryuji; Yokoyama, Keiichi; Yamanouchi, Kaoru*; Yokoyama, Atsushi
no journal, ,
When molecules are exposed to intense laser fields, dissociative ionization is efficiently induced and several decomposition pathways competes. The present study aims at revealing the correlation between the electronic states just after ionization and the following dissociation process. The photoelectron-photoion coincidence momentum imaging (PEPICO-MI) technique enables us to detect photoelectrons and photoions produced in a single event simultaneously. We applied PEPICO-MI to dissociative ionization of ethanol (C
H
OH), whose branching ratio varies as a function of the laser pulse duration. When ethanol molecules are irradiated with a short laser pulse, photoelectron images strongly depend on the correlated product ions.
Akagi, Hiroshi; Otobe, Tomohito; Staudte, A.*; Shiner, A.*; Turner, F.*; Villeneuve, D. M.*; Doerner, R.*; Corkum, P. B.*
no journal, ,
no abstracts in English
Nakamura, Tatsufumi; Fukuda, Yuji; Kishimoto, Yasuaki*
no journal, ,
XFEL light has unique feature of high photon energy of 12
20 keV and high flux of 10
/pulse/cm
. The irradiation of XFEL light onto Carbon clusters which model bio-molecules leads to generation of high energy electrons of 1220 keV via inner-shell ionization. These high energy electrons induces electric field of the order of TV/m at the surface and inside the target, which leads to field ionization. Depending on the laser intensity, this field ionization quickly ionizes all the outer shell electrons. By using PIC simulation code, which includes field ionization, collisional ionization, and Auger effect, we show how the target is ionized depending on laser intensity and target size.
Nakamura, Tatsufumi; Fukuda, Yuji; Yogo, Akifumi; Tampo, Motonobu; Kando, Masaki; Hayashi, Yukio; Kameshima, Takashi; Pirozhkov, A. S.; Esirkepov, T. Z.; Pikuz, T. A.*; et al.
no journal, ,
In this study, we propose the Coulomb implosion mechanism of the negative ion acceleration in laser plasmas. When a cluster target is irradiated by an intense laser pulse and the ponderomotive pressure of the laser light blows away the electrons, the repelling force of an uncompensated electric charge of positive ions causes the cluster Coulomb explosion. In the case of a multi-species cluster with a relatively small number of the negative ions, the electric field formed by the positively charged component accelerates the negative ions inward. The negative ions leave the target, passing through the center or bouncing its vicinity. Theoretical description and present the results of the Particle-in-Cell simulation of the Coulomb explosion/implosion of a multi-species cluster are presented at the meeting.
Matsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi
no journal, ,
Faenov, A. Y.; Fukuda, Yuji; Pikuz, T. A.*; Bulanov, S. V.; Tanaka, Momoko; Kishimoto, Maki; Ishino, Masahiko; Kato, Yoshiaki*; Kawachi, Tetsuya
no journal, ,
Okano, Yasuaki*; Nishikino, Masaharu; Nakahara, Shogo*; Tokita, Shigeki*; Masuno, Shinichiro*; Hashida, Masaki*; Sakabe, Shuji*; Nakano, Hidetoshi*; Kawachi, Tetsuya; Nishimura, Hiroaki*; et al.
no journal, ,
The generation of monoenergetic hard X-rays more than 10 keV has attracted much attention for X-ray imaging in the field of high density physics and biomedical applications. Our group is currently developing an X-ray microbeam system to study radiobiological effects of cells as fundamental study of radiation therapy. In such applications, improvement of conversion efficiency (CE) from the driving laser to X-rays is an important issue and some approaches for efficient X-ray generation up to several keV have been proposed so far using low density, surface-structured targets, such as porous metals, velvet targets, and carbon nanotubes (CNTs), with the concepts of improvement of the laser absorption efficiency. In this work, we investigated the yields of K-alpha emission from bare and aligned CNT-array coated metal targets to take baseline data aiming to improve the CE in hard X-ray region (multi-keV to tens of keV) by adapting such kind of method.
Fukuda, Yuji; Faenov, A. Y.; Tampo, Motonobu; Yogo, Akifumi; Pikuz, T. A.*; Kando, Masaki; Kotaki, Hideyuki; Daito, Izuru; Hayashi, Yukio; Kawase, Keigo; et al.
no journal, ,
A near-critical plasma cloud embedded in an underdense plasma, created by the interaction of laser prepulses with the cluster-gas target, is irradiated by the high-repetition laser pulses. Through a shadowgraphy, observed is a 3-mm long stable channel formation, from which high energy ions, accelerated up to 10 MeV/n in the laser propagation direction, are detected in a stack of plastic nuclear track detectors.
:LuLiF
crystalAkahane, Yutaka; Aoyama, Makoto; Sugiyama, Akira; Kubo, Ryoichi*; Ogawa, Kanade; Tsuji, Koichi; Yamakawa, Koichi
no journal, ,
A diode-pumped regenerative amplification with cryogenically cooled Yb : LuLiF crystal has been demonstrated for the first time to our knowledge. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated 6 mJ, 13 ps pulses at 999 nm in wavelength and 8.5 mJ, 27 ps pulses at 1024 nm, respectively, without a pulse compressor. Simultaneous lasing at 999 and 1024 nm was demonstrated, which could be used for different frequency generation in the terahertz region.
Kotaki, Hideyuki; Daito, Izuru; Kando, Masaki; Hayashi, Yukio; Kawase, Keigo; Kameshima, Takashi; Fukuda, Yuji; Homma, Takayuki; Ma, J.*; Chen, L. M.*; et al.
no journal, ,
Ogawa, Kanade; Aoyama, Makoto; Akahane, Yutaka; Tsuji, Koichi; Harimoto, Tetsuo*; Kawanaka, Junji*; Nishioka, Hajime*; Fujita, Masayuki*; Yamakawa, Koichi
no journal, ,
We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 550 nm bandwidth in the near-infrared region. We have observed a substantial enhancement (nearly 2-fold) of the parametric amplification bandwidth by using time-delayed two broadband pump pulses at degeneracy.