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Goto, Aki*; Michishio, Koji*; Oka, Toshitaka; Tagawa, Masahito*; Yamashita, Shinichi*
Langmuir, 39(34), p.11954 - 11963, 2023/08
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)Atomic oxygen (AO) is one of the dominant components of the residual atmosphere in low Earth orbit. AO collides with spacecraft with translational energy of 5 eV, forming nanoscale protrusions on polymeric materials. This study investigated the size of free-volume holes and the layer thickness that interacted with AO for polyethylene (PE), polypropylene (PP), and polystyrene (PS) by positron annihilation lifetime spectroscopy. By the AO irradiation, oxidized layer formed in the surface, and the maximum depth of the oxidized layer for PE and PP were deeper than for PS. The different sizes of free-volume holes would affect the injection depths of AO, resulting in the oxidized layers' thicknesses and surface morphologies.
Yokota, Kumiko*; Tagawa, Masahito*; Yoshigoe, Akitaka; Teraoka, Yuden
Journal of Surface Analysis, 20(3), p.221 - 225, 2014/03
Yokota, Kumiko*; Tagawa, Masahito*; Matsumoto, Koji*; Furuyama, Yuichi*; Kitamura, Akira*; Kanda, Kazuhiro*; Tode, Mayumi; Yoshigoe, Akitaka; Teraoka, Yuden
Protection of Materials and Structures from the Space Environment; Astrophysics and Space Science Proceedings, Vol.32, p.531 - 539, 2012/08
Tagawa, Masahito*; Kishida, Kazuhiro*; Yokota, Kumiko*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden; Zhang, J.*; Minton, T. K.*
Protection of Materials and Structures from the Space Environment; Astrophysics and Space Science Proceedings, Vol.32, p.547 - 555, 2012/08
Kanda, Kazuhiro*; Yokota, Kumiko*; Tagawa, Masahito*; Tode, Mayumi; Teraoka, Yuden; Matsui, Shinji*
Japanese Journal of Applied Physics, 50(5), p.055801_1 - 055801_3, 2011/05
Recently, the irradiation of soft X-ray synchrotron radiation (SR) to highly-hydrogenated diamond-like-carbon (H-DLC) films in vacuum results in the desorption of hydrogen and the increase of film density, hardness and refractive index. In this study, we investigated SR irradiation effects on the H-DLC with different hydrogen contents. The H-DLC thin films were deposited on an Si wafer with 200 nm thickness by an amplitude-modulated radio frequency plasma chemical vapor deposition method. The SR irradiation was carried out at NewSUBARU BL6. The SR has a continuous spectrum from IR to soft X-ray, which is lower than 1 keV. The hydrogen content dependence on SR dose was estimated using elastic recoil detection analysis (ERDA) and Rutherford backscattering (RBS) techniques. The hydrogen content was kept constant in the low-hydrogenated DLC film, while that in the high-hydrogenated DLC film decreased exponentially with soft X-ray dose.
Kanda, Kazuhiro*; Yokota, Kumiko*; Tagawa, Masahito*; Tode, Mayumi; Teraoka, Yuden; Matsui, Shinji*
Japanese Journal of Applied Physics, 50(5), p.055801_1 - 055801_3, 2011/05
Times Cited Count：11 Percentile：43.98(Physics, Applied)Tagawa, Masahito*; Yokota, Kumiko*; Kitamura, Akira*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden; Kanda, Kazuhiro*; Niibe, Masahito*
Applied Surface Science, 256(24), p.7678 - 7683, 2010/10
Times Cited Count：13 Percentile：50.83(Chemistry, Physical)Surface structural changes of a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy (RBS), synchrotron radiation photoelectron spectroscopy (SR-PES), and near-edge X-ray absorption fine structure (NEXAFS). It was confirmed that the DLC surface was oxidized and etched by high-energy collisions of atomic oxygen. RBS and real-time mass-loss data showed a linear relationship between etching and atomic oxygen fluence. SR-PES data suggested that the oxide layer was restricted to the topmost surface of the DLC film. NEXAFS data were interpreted to mean that the sp
structure at the DLC surface was selectively etched by collisions with hyperthermal atomic oxygen, and an sp
-rich region remained at the topmost DLC surface. The formation of an sp-rich layer at the DLC surface led to surface roughening and a reduced erosion yield relative to the pristine DLC surface.
Sakuraba, Naotoshi; Numata, Masami; Komiya, Tomokazu; Ichise, Kenichi; Nishi, Masahiro; Tomita, Takeshi; Usami, Koji; Endo, Shinya; Miyata, Seiichi; Kurosawa, Tatsuya; et al.
JAEA-Technology 2009-071, 34 Pages, 2010/03
JAEA-Technology-2009-071.pdf:21.07MB
As a part of maintenance technology of a large-sized glove box for handling of TRU nuclides, we developed replacement technology for front acrylic panels using the bag-in/bag-out method and applied this technology to replace the deteriorated front acrylic panels at Waste Safety Testing Facility (WASTEF) in Nuclear Science Research Institute of Japan Atomic Energy Agency (JAEA). As a consequence, we could safely replace the front acrylic panels under the condition of continuous negative pressure only with partial decontamination of the glove box. We also demonstrated that the present technology is highly effective in points of safety, workability and cost as compared to the usual replacement technology for front acrylic panels of a glove box, where workers in an air-line suit replace directly the front acrylic panels in a green house.
Tagawa, Masahito*; Yokota, Kumiko*; Maeda, Kenichi*; Yoshigoe, Akitaka; Teraoka, Yuden; Akamatsu, Kensuke*; Nawafune, Hidemi*
Polyimides and Other High-Temperature Polymers; Synthesis, Characterization and Applications, Vol.5, p.249 - 259, 2009/08
Surface fluorination of PMDA-ODA polyimide has been performed by a hyperthermal F beam. The fundamental properties of the F-beam-exposed polyimide surface are reported based on the analytical results by X-ray photoelectron spectroscopy and contact angle measurements. It was observed that CF, CF
or CF
moieties were formed at the polyimide surfaces depending on the F beam fluences. Advancing contact angles of water can be controlled from 60 to 120 degrees by varying the F beam fluences. Surface roughness analyzed by atomic force microscopy slightly increased with atomic F beam exposures due probably to the formation of volatile products such as CF
. This is confirmed by the mass change during F beam exposure by a quartz crystal microbalance.
Tagawa, Masahito*; Yokota, Kumiko*; Maeda, Kenichi*; Yoshigoe, Akitaka; Teraoka, Yuden
Applied Physics Express, 2(6), p.066002_1 - 066002_3, 2009/06
Times Cited Count：3 Percentile：14.44(Physics, Applied)Hyperthermal (kinetic energy of 10 eV) fluorine atom beam interaction with highly oriented pyrolytic graphite (HOPG) was studied. Surface analytical results of atomic fluorine-exposed HOPG using synchrotron radiation photoelectron spectroscopy showed that the fluorine reaction was limited at the topmost HOPG(0001) layer. This is due to the fact that the kinetic energy of 10 eV is not sufficient to penetrate graphite layer but is enough for breaking C-C bonds and forms CF and CF functional groups through the beam-induced fluorination reactions. It was demonstrated that the use of hyperthermal energy in the range of 10 eV is advantageous for damage-free modification of the topmost surface of carbon-based materials.
Yokota, Kumiko*; Tagawa, Masahito*; Kitamura, Akira*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden; Fontaine, J.*; Belin, M.*
Transactions of the Japan Society for Aeronautical and Space Sciences, Space Technology Japan (Internet), 7(ists26), p.Pc_37 - Pc_42, 2009/06
The effect of hyperthermal atomic oxygen (AO) exposure on a surface property of Si-doped DLC was investigated. Two types of DLC were tested which contain Si atoms approximately 10 at% and 20 at%. Surface analytical results of high-resolution X-ray photoelectron spectroscopy using synchrotron radiation (synchrotron radiation photoemission spectroscopy; SR-PES) as well as Rutherford backscattering spectroscopy (RBS) have been used for characterization of the AO-exposed Si-doped DLC. It was identified by SR-PES that the SiO layer was formed by the hyperthermal AO exposure at the Si-doped DLC surface. RBS data indicates that AO exposure leads to severe thickness loss on the non-dope DLC, in contrast, SiO layer formed by the hyperthermal atomic oxygen reaction at the Si-doped DLC protects the DLC underneath the SiO layer.
Yokota, Kumiko*; Tagawa, Masahito*; Kitamura, Akira*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden
Applied Surface Science, 255(13-14), p.6710 - 6714, 2009/04
Times Cited Count：13 Percentile：50.25(Chemistry, Physical)The densities of hydrogen and carbon atoms in a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy and elastic recoil detection analysis. The hydrogen density in DLC decreased upon atomic oxygen exposure with collision energy as low as 2 eV, whereas an exposure greater than 3 eV was necessary to remove carbon atoms. A high collision energy also led to hydrogen desorption in the deeper region of DLC. The surface density of hydrogen decreased 6% by atomic oxygen exposure, and was independent of the collision energy. Additionally, the non-bonded hydrogen, which could diffuse in DLC, was desorbed by the energy transfer from the atomic oxygen collisions.
Yokota, Kumiko*; Tagawa, Masahito*; Kitamura, Akira*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden; Fontaine, J.*; Belin, M.*
AIP Conference Proceedings 1087, p.368 - 383, 2008/05
The effect of hyperthermal atomic oxygen (AO) exposure on a surface property of Si-doped DLC was investigated. Two types of DLC were tested which contain Si atoms approximately 10 at% and 20 at%. Surface analytical results of high-resolution X-ray photoelectron spectroscopy using synchrotron radiation (synchrotron radiation photoemission spectroscopy; SR-PES) as well as Rutherford backscattering spectroscopy (RBS) have been used for characterization of the AO-exposed Si-doped DLC. It was identified by SR-PES that the SiO layer was formed by the hyperthermal AO exposure at the Si-doped DLC surface. RBS data indicates that AO exposure leads to severe thickness loss on the non-dope DLC, in contrast, SiO layer formed by the hyperthermal atomic oxygen reaction at the Si-doped DLC protects the DLC underneath the SiO layer.
and diamond-like carbon lubricating films; Atomic oxygen-induced erosion and its effect on tribological propertiesTagawa, Masahito*; Yokota, Kumiko*; Matsumoto, Koji*; Suzuki, Mineo*; Teraoka, Yuden; Kitamura, Akira*; Belin, M.*; Fontaine, J.*; Martin, J. M.*
Surface & Coatings Technology, 202(4-7), p.1003 - 1010, 2007/12
Times Cited Count：63 Percentile：89.41(Materials Science, Coatings & Films)Effects of 5 eV atomic oxygen beam on MoS and diamond-like carbon (DLC) lubrication films are evaluated relevance to space environmental effects in the low Earth orbit. X-ray photoelectron spectra indicate that the loss of S atoms and Mo oxidation at the atomic oxygen irradiated MoS is significant. Depth profiles of S and Mo indicate that the oxidation is restricted within 3 nm from the surface. This is due to the fact that Mo oxide plays as a protective layer against further oxidation. The surface oxidation affects the friction coefficient. However, due to the delamination of oxide layer, wear-life of the film is reduced in some conditions. In contrast, no sever oxidation states of C atoms are detected at DLC surface. However, the loss of DLC itself is measured by Rutherford backscattering spectroscopy. It is concluded that the protection of DLC film is mandatory for the use of DLC in the LEO space applications.
Tagawa, Masahito*; Yokota, Kumiko*; Tsumamoto, Shinnosuke*; Sogo, Chie*; Yoshigoe, Akitaka; Teraoka, Yuden
Applied Physics Letters, 91(3), p.033504_1 - 033504_3, 2007/07
Times Cited Count：5 Percentile：22.64(Physics, Applied)A direct oxidation reaction of Si atoms on an Si(001) surface was studied by ellipsometry and synchrotron radiation photoemission spectroscopy. In-situ ellipsometry measurements when exposed to 2.7-5.0 eV O atom beams indicated that oxide growth followed a linear relationship with an O atom fluence up to an oxide thickness of 0.6-0.7 nm. In contrast, the limit of linear growth was 0.3 nm in the case of the 1.8 eV beam. These results suggest that the backbonds of Si atoms in the first layer are directly oxidized by O atom with a translational energy between 2.7-5.0 eV.
Hayakawa, Ryoma*; Nakae, Mari*; Yoshimura, Takeshi*; Ashida, Atsushi*; Fujimura, Norifumi*; Uehara, Tsuyoshi*; Tagawa, Masahito*; Teraoka, Yuden
Journal of Applied Physics, 100(7), p.073710_1 - 073710_8, 2006/10
Times Cited Count：12 Percentile：42.56(Physics, Applied)A structural analysis and dielectric property measurements of silicon nitride films fabricated using atmospheric pressure (AP) plasma were carried out, and the results were compared to a radio frequency (RF) plasma case. Using AP plasma, 1.8-nm-thick films composed of SiN
O
were obtained in the temperature range from 298 to 773 K. X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry revealed 10% more nitrogen atoms corresponding to the NSi bond in the film using AP plasma than those using RF plasma. In the temperature range, the leakage current densities were not affected by the temperature. Films fabricated at 298 K showed leakage current density of as low as 7
10
A/cm at 5MV/cm. This value was one order of magnitude lower than that using RF plasma.
Tagawa, Masahito*; Sogo, Chie*; Yokota, Kumiko*; Yoshigoe, Akitaka; Teraoka, Yuden; Shimura, Takayoshi*
Applied Physics Letters, 88(13), p.133512_1 - 133512_3, 2006/03
Times Cited Count：8 Percentile：31.28(Physics, Applied)Synchrotron radiation photoelectron spectroscopy (SR-PES) and crystal truncation rod (CTR) scattering profiles were used to investigate an ultrathin SiO overlayer on an Si(001) surface formed by a 5 eV O-atom beam at room temperature. The SR-PES spectra indicated that the suboxides in the O-atom-beam oxidized film were concentrated on the SiO surface rather than at the Si/SiO interface. The CTR scattering data of the O-atom-beam oxidation film had a lower intensity near (1 1 L) (0.3-L-0.8), suggesting a lower content of the SiO ordered structure in the oxide film. An inverse diffusion of the interstitial Si atoms in the oxidation kinetics can explain the data.
film formed by a hyperthermal O-atom beam at room temperatureTagawa, Masahito*; Sogo, Chie*; Yokota, Kumiko*; Hachiue, Shunsuke; Yoshigoe, Akitaka; Teraoka, Yuden
Japanese Journal of Applied Physics, 44(12), p.8300 - 8304, 2005/12
Times Cited Count：5 Percentile：21.82(Physics, Applied)Si oxide layers formed on Si(001) substrates by irradiation of hyperthermal oxygen atomic beams at room temperature were analysed at the JAERI soft X-ray beamline by photoemission spectroscopy. It was found that sub-oxide components were scarcely observed in the Si oxide layers formed by the atomic oxygen beam.
Tagawa, Masahito*; Sogo, Chie*; Miyagai, Suguru*; Yokota, Kumiko*; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
Ultra-thin oxide-layers on Si(001) surfaces, formed by an atomic oxygen beam with hyperthermal incident energy, were analysed by photoemission spectroscopy with synchrotron radiation. The formation of ultra-thin oxide-layers was performed in Kobe University. The photoemission spectroscopy was performed at the surface chemistry experimental station installed in the JAEA soft X-ray beamline in the SPring-8. Comparing the photoemission spectra with those of thermal oxidation with oxygen gas, it was found that a few suboxides were observed in the ultra-thin oxide-layers formed by atomic oxygem beams.
Yokota, Kumiko*; Tagawa, Masahito*; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
The oxide film formed on Si(001) in a simulated low-Earth-orbit(LEO)-space environment was analyzed by synchrotron radiation photoelectron spectroscopy (SR-PES). The SR-PES results clearly indidcated that the amount of suboxides at the Si/SiO interface formed in a simulated LEO environment at room temperature was much lower than that formed by an ordinary high-temperature oxidation process.
