著者

Oh Junepyo Kondo Takahiro Hatake Daigo Honma Yujiro Arakawa Keitaro Machida Takahiro Nakamura Junji

出版者

IOP Publishing

雑誌

Journal of physics. Condensed matter (ISSN:09538984)

巻号頁・発行日

vol.22, no.30, pp.304008, 2010-07-13

被引用文献数

8 6

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The effect of the local electronic modification of the graphite surface on the gas–graphite interaction has been investigated by the molecular beam scattering technique. The angular intensity distributions of He and Ar beams scattered from pristine and defect induced graphite surfaces have been measured at various surface temperatures. From the He scattering results, the cross-section for the He diffuse scattering per defect is estimated as being as much as 113 nm2. The origin of the extremely large cross-section is ascribed to the modulated electronic states of graphite around the defect based on the STM measurements, which is due to the local breaking of the π conjugated system of graphite. From the Ar scattering results, the effective mass of the graphite surface for the Ar collision has been estimated as M = 114 u, based on the analysis with the hard cube model. The new component appears in the scattering distribution of Ar for the defect induced graphite surface. The component has a larger peak position angle than that for the pristine graphite surface, indicating that the normal component of the translational energy of the Ar atom was greatly lost by the collision at the electronically modified area of graphite.

著者

Kondo Takahiro Kato Hiroyuki S. Bonn Mischa Kawai Maki

出版者

American Institute of Physics

雑誌

The journal of chemical physics (ISSN:00219606)

巻号頁・発行日

vol.126, no.18, pp.181103, 2007-05

被引用文献数

29 17

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The isothermal crystallization process of thin amorphous solid water (ASW) films on Ru(0001) has been investigated in real time by simultaneously employing helium atom scattering, infrared reflection absorption spectroscopy, and isothermal temperature-programmed desorption. The measurements reveal that the crystallization mechanism consists of random nucleation events in the bulk of the ASW films, followed by homogeneous growth. Morphological changes of the solid water film during crystallization expose the water monolayer just above the substrate to the vacuum during the crystallization process.

著者

Kondo Takahiro Honma Yujiro Oh Junepyo Machida Takahiro Nakamura Junji

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.82, no.15, pp.153414, 2010-10

被引用文献数

50

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We report nonuniform and long-range electronic perturbation of graphite near the Fermi level by the point defect based on the measurements with scanning tunneling spectroscopy. The states propagate with threefold symmetry perpendicular to the zigzag edges at the point defect, indicating the formation of the nonbonding states. The propagation continues for 3–4 nm from the defect and is accompanied by oscillations in the state energy and state intensity with a periodicity of (√3×√3)R30°. The oscillation in the state intensity is ascribed to the disruption in the π-conjugated system in graphite around the defect, i.e., edge-states propagation from the defect while the oscillation in the state energy is ascribed to electron-electron interactions between the nonbonding π electronic states and the standing-wave caused by π bands of graphite.

著者

Kondo Takahiro Kato Hiroyuki S. Bonn Mischa Kawai Maki

出版者

American Institute of Physics

雑誌

The journal of chemical physics (ISSN:00219606)

巻号頁・発行日

vol.127, no.9, pp.094703, 2007-09

被引用文献数

41 20

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The deposition and the isothermal crystallization kinetics of thin amorphous solid water (ASW) films on both Ru(0001) and CO-precovered Ru(0001) have been investigated in real time by simultaneously employing helium atom scattering, infrared reflection absorption spectroscopy, and isothermal temperature-programmed desorption. During ASW deposition, the interaction between water and the substrate depends critically on the amount of preadsorbed CO. However, the mechanism and kinetics of the crystallization of ~50 layers thick ASW film were found to be independent of the amount of preadsorbed CO. We demonstrate that crystallization occurs through random nucleation events in the bulk of the material, followed by homogeneous growth, for solid water on both substrates. The morphological change involving the formation of three-dimensional grains of crystalline ice results in the exposure of the water monolayer just above the substrate to the vacuum during the crystallization process on both substrates.