Papers by Author: Atsuo Kawasuso

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Authors: Atsuo Kawasuso, Masashi Suezawa, Mitsuru Hasegawa, S. Yamaguchi, Koji Sumino
Authors: Atsuo Kawasuso, F. Redmann, Reinhard Krause-Rehberg, Peter Sperr, Thomas Frank, Michael Weidner, Gerhard Pensl, Hisayoshi Itoh
Authors: Atsuo Kawasuso, Masuyuki Hasegawa, Masashi Suezawa, S. Yamaguchi, Koji Sumino
Authors: Masaki Maekawa, Atsuo Kawasuso, Tetsuya Hirade, Y. Miwa
Abstract: We have developed a positron microbeam using magnetic lenses based on the commercial scanning electron microscope. The minimum beam diameter was 1.9 μm on target. Two-dimensional image of S parameter was successfully obtained. Using this apparatus, S parameter distribution around the crack tip introduced by a stress corrosion cracking of a stainless steel was obtained. S parameter increases at the further region of the tip of the crack. This shows that vacancy type defects may be generated as crack precursor.
Authors: Atsuo Kawasuso, Yuki Fukaya, M. Hashimoto, Ayahiko Ichimiya, H. Narita, I. Matsuda
Abstract: In this work, we studied a few surfaces, of which the structures have not yet been revealed, using reflection high-energy positron diffraction (RHEPD). We studied the Ge(111)/Pb and Ge(111)/Sn surfaces that exhibit the phase transition from 3×3 to √3×√3 periodicities at around 200K. We found that in both phases the equilibrium positions of Pb and Sn adatoms are conserved. That is, in the unit-cell, one of three adatoms is located upper position and two of them are located lower positions (one-up-two-down). The phase transition is interpreted in terms of an order-disorder type. We furthermore studied the quasi-one dimensional Si(111)/In surface which exhibits the metal-insulator transition at around 120K. The high temperature phase is well explained as the zigzag chain structure. We found that a dynamic atomic displacement which leads to the formation of hexagon structure occur below 120 K. We confirmed the appearance of the band gap using the surface structure determined from the RHEPD rocking curves.
Authors: Atsuo Kawasuso, Hisayoshi Itoh, Dai Bum Cha, Sohei Okada
Authors: Yoshimasa Horii, Atsuo Kawasuso, Masuyuki Hasegawa, Masashi Suezawa, S. Yamaguchi, Koji Sumino
Authors: F. Redmann, Atsuo Kawasuso, Konrad Petters, Reinhard Krause-Rehberg, Hisayoshi Itoh
Authors: Dai Bum Cha, Hisayoshi Itoh, Norio Morishita, Atsuo Kawasuso, Takeshi Ohshima, Yuichi Watanabe, J. Ko, Kin Kiong Lee, Isamu Nashiyama
Authors: Masaki Maekawa, Atsuo Kawasuso, Masahito Yoshikawa, Ayahiko Ichimiya
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