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Journal Articles

Temperature dependence of positron annihilation lifetime in near-surface and bulk of room-temperature ionic liquid observed by a slow positron beam

Hirade, Tetsuya; Michishio, Koji*; Kobayashi, Yoshinori*; Oshima, Nagayasu*

Chemical Physics Letters, 795, p.139507_1 - 139507_4, 2022/05

We obtained the temperature dependence up to 150$$^{circ}$$C of the triplet positronium ($$ortho$$-Ps) lifetime in N,N,N-Trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide (TMPA-TFSI) by the vertical slow positron beamline installed at AIST. Positrons penetrate into the liquid surface of TMPA-TFSI with the positron energies of 2 keV and 12 keV to investigate at the near-surface and the balk. The surface structure was visible at 150$$^{circ}$$C, 120$$^{circ}$$C above the melting temperature. The $$ortho$$-Ps lifetime became shorter at higher temperatures for both positron energies. Similar temperature dependence had appeared just in water as the result of the reaction of $$ortho$$-Ps and radiolysis products such as the OH radicals. The temperature dependence observed for TMPA-TFSI suggested that the chemical reaction of $$ortho$$-Ps occurred.

Journal Articles

Temperature dependence of ortho-positronium annihilation in room temperature ionic liquids

Hirade, Tetsuya; Michishio, Koji*; Kobayashi, Yoshinori*; Oshima, Nagayasu*

Acta Physica Polonica A, 137(2), p.109 - 112, 2020/02

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Recently, it was reported that the positronium (Ps) bubble in Room Temperature Ionic Liquids (RTILs) showed some phenomena that were very different from them observed in other molecular liquids. Now the reason of these interesting phenomena is being understood. The structure caused by the ionic interaction between anions and cations can exist even at the higher temperatures than the melting temperatures. It was the reason why the oscillation of Ps bubble was observed at the temperatures near the melting temperatures in RTILs. The temperature dependence of the Ps bubble size estimated by the triplet Ps ($$ortho$$-Ps) pick-off annihilation lifetime indicated that there was a nano-meter structure remained by ionic interactions even at high temperatures. The $$ortho$$-Ps pick-off annihilation lifetime will be a strong tool to study nano-structure in RTILs.

Journal Articles

Research progress at the Slow Positron Facility in the Institute of Materials Structure Science, KEK

Hyodo, Toshio*; Wada, Ken*; Mochizuki, Izumi*; Kimura, Masao*; Toge, Nobukazu*; Shidara, Tetsuo*; Fukaya, Yuki; Maekawa, Masaki*; Kawasuso, Atsuo*; Iida, Shimpei*; et al.

Journal of Physics; Conference Series, 791(1), p.012003_1 - 012003_8, 2017/02

 Times Cited Count:3 Percentile:82.4

no abstracts in English

Journal Articles

Increase in the beam intensity of the linac-based slow positron beam and its application at the Slow Positron Facility, KEK

Wada, Ken*; Hyodo, Toshio*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; Fukaya, Yuki; et al.

European Physical Journal D, 66(2), p.37 - 40, 2012/02

 Times Cited Count:34 Percentile:86.14(Optics)

no abstracts in English

Oral presentation

Recent development of the slow positron facility at institute of materials structure science, KEK

Wada, Ken*; Hyodo, Toshio*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Suzuki, Ryohei*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

The New experiment stations at KEK Slow Positron Facility

Wada, Ken*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Ikeda, Mitsuo*; Osawa, Satoshi*; Shidara, Tetsuo*; Michishio, Koji*; Tachibana, Takayuki*; Nagashima, Yasuyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Increase in the intensity and brightness enhancement of the slow positron beam and its application at the Slow Positron Facility, KEK

Wada, Ken*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Yagishita, Akira*; Ikeda, Mitsuo*; Osawa, Satoshi*; Suwada, Tsuyoshi*; Furukawa, Kazuro*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Beam-line improvement and new experiment stations of KEK-IMSS slow-positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Beam-line improvement and recent results of KEK-IMSS slow-positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Present status of the KEK-IMSS Slow Positron Facility; A New beam-line branch and a rearrangement of the experiment stations

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Recent developments and results of the KEK slow positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Materials science at the KEK slow positron facility

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.

no journal, , 

no abstracts in English

Oral presentation

Introduction to the slow positron facility at KEK

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Michishio, Koji*; Terabe, Hiroki*; Iida, Shimpei*; Nagashima, Yasuyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Application of a linac-based intense slow-positron beam to diffraction experiments

Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Shidara, Tetsuo*; Fukaya, Yuki; Maekawa, Masaki; Kawasuso, Atsuo; Michishio, Koji*; Terabe, Hiroki*; Iida, Shimpei*; et al.

no journal, , 

no abstracts in English

Oral presentation

Temperature dependence of ortho-positronium lifetime in a room temperature ionic liquid

Hirade, Tetsuya; Michishio, Koji*; Kobayashi, Yoshinori*; Oshima, Nagayasu*

no journal, , 

Positronium (Ps) forms bubbles in liquids, and the bubbles become larger due to the lower surface tension at higher temperatures, resulting in longer o-Ps lifetimes. In room-temperature ionic liquids, it has been shown that the structure of Ps bubble is different and depends on the structure formed by the Coulomb force of the ions. We successfully obtained that the o-Ps lifetime did not increase at high temperatures. The existence of new state of Ps bubble was further clarified.

Oral presentation

Microstructure formation on polymer surfaces induced by atomic oxygen irradiation; Free volumes of polymer surfaces

Goto, Aki*; Tagawa, Masahito*; Michishio, Koji*; Oka, Toshitaka; Yamashita, Shinichi*

no journal, , 

Films of polyethylene, polypropylene and polystyrene were irradiated with AO, and their surface morphologies and free volumes were investigated. Nanoscale protrusions were formed for all sample surfaces with the AO fluences of $$10^{18}$$ atoms/cm$$^{2}$$ - $$10^{19}$$ atoms/cm$$^{2}$$. The free volumes in the surfaces within 40 nm - 50 nm decreased due to the AO irradiations.

Oral presentation

Microstructure formation on polymers induced by atomic oxygen; Higher-order structure effects on morphologies

Goto, Aki*; Tanji, Takashi*; Tagawa, Masahito*; Michishio, Koji*; Oka, Toshitaka; Yamashita, Shinichi*

no journal, , 

Atomic oxygen (AO) is a dominant constituent of residual atmosphere in low Earth orbit, it is necessary to evaluate materials' durability against AO before launching but the mechanism for the microstructure formation has not been understood. In this study, we irradiated AO to polymer surface and investigated the change of surface morphologies. The mass losses of irradiated polymers were similar regardless of polymer's type and temperature, however, the formed protrusions became larger and fewer with increasing temperature. This shows that the polymer chains' thermal motions affected the surface morphologies.

17 (Records 1-17 displayed on this page)
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