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Akagi, Hiroshi; Staudte, A.*; Shiner, A.*; Turner, F.*; Villeneuve, D. M.*; Ivanov, M. Yu.*; Corkum, P. B.*
no journal, ,
Angular dependence of tunnel ionization from a molecule in a strong laser field reflects the structure of the molecular orbital the electron tunnels from. Ours are the first measurements for a heteronuclear molecule. To determine the angle, we use circularly polarized light and detect the electron and fragment ion in coincidence. Concentrating on HCl, bond softening allows us to select the tunnel ionization from HOMO-1. The angular distribution is consistent with the shape of the orbital, modified by a contribution from the dipole moment of the neutral molecule and its cation.
Gejo, Tatsuo*; Iseda, Mitsuhiro*; Homma, Kenji*; Harries, J.; Tamenori, Yusuke*
no journal, ,
When a cluster undergoes inner-shell excitation, as well as electrons and ions fluorescence photons can also be detected. Depending on the excited state, the lifetime of this fluorescence is different, and so recording the arrival times of the photons relative to the exciting radiation, information can be obtained on the excited state distribution. This technique has previously been applied to the helium atom and water molecule, and is applied to clusters for the first time here. For argon clusters there are broadly two lifetime components, and their origin is discussed.
Kuniwake, Miki*; Harries, J.; Homma, Kenji*; Gejo, Tatsuo*
no journal, ,
When the O 1s electron of a water molecule is excited, Auger decay and dissociation occurs. Near threshold, the Auger electron is faster than the photo-electron, a post-collision interaction (PCI) occurs, and the photoelectron can be recaptured by either the parent ion or a fragment ion. Here we use Auger electron spectroscopy to investigate this process.
Itakura, Ryuji; Hasegawa, Hirokazu*; Kurosaki, Yuzuru; Yokoyama, Atsushi; Oshima, Yasuhiro*
no journal, ,
Nonadiabatic rotational excitation of molecules proceeds in intense laser fields. As the laser intensity increases, not only rotational excitation, but also tunnel ionization occurs. In the present study, rotational excitation dynamics accompanied by ionization is investigated through the resonant two-photon ionization measurement with a weak ns dye laser. Additionally, numerical simulations are performed introducing an imaginary potential into the time-dependent Schrodinger equation for describing ionization processes properly.
Saeki, Morihisa; Sasaki, Yuji; Yokoyama, Atsushi
no journal, ,
no abstracts in English
Shiga, Motoyuki
no journal, ,
Path integral molecular dynamics is a simulation method that can treat with nuclear quantum effect. On the other hand, ONIOM method is known as an efficient way to deal with large molecular systems. In this study, the combination of these two methods is applied to a quantum simulation of aqueous solutions, and the performance of this approach is discussed.
(
P) state of I
in an intense laser fieldMatsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi
no journal, ,
no abstracts in English
Fujii, Kentaro; Yokoya, Akinari; Shikazono, Naoya
no journal, ,
To investigate the K-shell photoabsorption effect (photoelectric effect and subsequent secondary electron effect) of DNA damage, dry plasmid DNA (pUC18) films were irradiated with synchrotron monochromatic soft X-rays (270, 435, 560, and 760 eV). Irradiated plasmid DNA was analyzed by agarose gel electrophoresis and the yields of strand breaks were determined by measuring the band intensity of the separated closed circular, open circular and linear forms of the plasmid DNA. The yields of base lesions were determined by the post-irradiation-treatment of the DNA with enzymatic probes (Fpg and Nth) which excise base lesionand visualized it as a strand break. The obtained yields of single strand break (SSB) and the base lesions revealed by enzymatic sensitive sites (ESS) of Fpg and Nth showed the characteristic dependence for photon energy. This result indicates that DNA lesions are induced through varieties of reaction pathways after core-electron ionizations.
Yokoyama, Atsushi
no journal, ,
no abstracts in English
clusters and its application to nanostructure imagingFukuda, Yuji; Faenov, A. Y.; Pikuz, T. A.*; Kando, Masaki; Kotaki, Hideyuki; Daito, Izuru; Homma, Takayuki; Kawase, Keigo; Kameshima, Takashi; Kawachi, Tetsuya; et al.
no journal, ,
The novel soft X-ray light source using the supersonic expansion of the mixed gas of He and CO, when irradiated by a femtosecond Ti:sapphire laser pulse, is observed to enhance the radiation of soft X-rays from the CO clusters. Using this soft X-ray emissions, nanostructure images of 100-nm thick Mo foils in a wide field of view (mm scale) with high spatial resolution (800 nm) are obtained with high dynamic range LiF crystal detectors.
-Co films with giant tunnel magnetoresistance effectMatsumoto, Yoshihiro; Sakai, Seiji; Naramoto, Hiroshi*; Nakagawa, Takeshi*; Takagi, Yasumasa*; Yokoyama, Toshihiko*; Shimada, Toshihiro*; Mitani, Seiji*; Takanashi, Koki; Maeda, Yoshihito
no journal, ,
no abstracts in English