Slow Positron Beam Apparatus for Surface and Subsurface Analysis of Samples in Air

Oshima, Nobuyuki; O’Rourke, Brian; Kuroda, R.; Suzuki, Ryoichi; Watanabe, Hirokazu; Kubota, Shoji; Tenjinbayashi, K.; Uedono, Akira; Hayashizaki, Noriyosu

doi:10.1143/apex.4.066701

Cited by 15 publications

(19 citation statements)

References 16 publications

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“…For the investigation at hand, Teflon AF 1600 was used because Teflon AF 1600 has a very long o-Ps lifetime component of between 5 and 6 ns, and so the large change of this lifetime component in the interphase can be easily detected. 22 In the SiN substrate, no o-Ps is formed, 21 so we can exclude an influence on the measured o-Ps lifetime from the substrate. A schematic of the sample setup and the implantation profile can be seen in Figure 2.…”

Section: ■ Introductionmentioning

confidence: 99%

Free Volume Profiles at Polymer–Solid Interfaces Probed by Focused Slow Positron Beam

et al. 2015

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The properties of materials involving polymer−solid interfaces are determined not only by the properties of the constituents but also by the interfacial region of the polymer near the solid, the socalled interphase. Here we report on positron annihilation lifetime spectroscopy (PALS) measurements of the free volume near the interface with a focused positron beam. The measurements were performed at an interface between a Teflon AF 1600 film and a 30 nm thick SiN membrane from the backside of a Si substrate which was locally etched away to expose the ultrathin SiN membrane. We were able to focus the positron beam onto the exposed region and to probe the SiN−Teflon AF 1600 interfacial region with low implantation energies, resulting in very narrow implantation profiles and excellent depth resolution. We found a pronounced decrease in orthopositronium lifetime close the interface. On the basis of modeling, we could estimate the interphase width and the average density increase in the interfacial region as ∼12 nm and 5−7%, respectively.

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Section: ■ Introductionmentioning

confidence: 99%

Free Volume Profiles at Polymer–Solid Interfaces Probed by Focused Slow Positron Beam

et al. 2015

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“… is the material density (in g/cm 3 ) and  is the Gamma function. Neglecting backscatter, the transmission through a film of a certain depth can be estimated by integrating this function.…”

Section: Positron Transmission Fractionmentioning

confidence: 99%

“…used to successfully extract slow positrons outside the vacuum chamber [3,4]. Three different windows have been used with the following dimensions; 30 nm  0.6 mm  0.6 mm, 200 nm  1.5 mm  1.5 mm and 500 nm  3.0 mm  3.0 mm.…”

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“…Three different windows have been used with the following dimensions; 30 nm  0.6 mm  0.6 mm, 200 nm  1.5 mm  1.5 mm and 500 nm  3.0 mm  3.0 mm. The density of the SiN windows is around 3.0 g/cm 3 and the compositional ratio of Si to N is approximately 1 : 1 [3]. When one side of the window is evacuated to vacuum the window bends slightly towards the vacuum side.…”

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confidence: 99%

“…If we consider the SiN -Gas layer -Sample as a multilayer system, the stopping probability  i of positrons in the i-th layer is given by [1,3];…”

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Monte Carlo simulations of the extraction of slow positrons into gas through thin SiN windows

O’Rourke

Zhou

Oshima

et al. 2013

J. Phys.: Conf. Ser.

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Probing the internal structure of reverse osmosis membranes by positron annihilation spectroscopy: Gaining more insight into the transport of water and small solutes

Fujioka

Oshima

Suzuki

et al. 2015

Journal of Membrane Science

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. Probing the internal structure of reverse osmosis membranes by positron annihilation spectroscopy: gaining more insight into the transport of water and small solutes. Journal of Membrane Science, Probing the internal structure of reverse osmosis membranes by positron annihilation spectroscopy: gaining more insight into the transport of water and small solutes AbstractReverse osmosis (RO) has been employed as a key separation process in many industrial applications. In recent years, the use of positron annihilation spectroscopy (PAS) including positron annihilation lifetime spectroscopy (PALS) and Doppler broadening of annihilation radiation to characterise the internal structure of the skin layer of thin film composite membranes has renewed research interest for further development and optimisation of the RO process. In this paper, we highlight the need for better understanding of the skin layer internal structure. We review relevant PAS techniques that could provide an unprecedented level of insight to our understanding of the internal structure of the active skin layer of RO membranes. PALS data reported in previous studies revealed that commercially available RO membranes have a mean free-volume hole-radius of 0.20-0.29 nm in the active skin layer. Data corroborated from the literature show a good correlation between the mean free-volume hole-radius of RO membranes and the rejection of boric acid which can be considered as a model small and neutral solute. The data also highlight the need for a comprehensive inter-laboratory study to standardise free-volume hole-radius measurement using PALS. In addition to free-volume holeradius, free-volume fraction and thickness of the active skin layer appear to be important membrane properties governing neutral solute rejection. A roadmap is suggested to enhance the understanding of the transport of small and neutral solutes in RO. This includes integrating PAS with other techniques (e.g. molecular dynamics simulation) to describe the internal structure of RO membranes. Reverse osmosis (RO) has been employed as a key separation process in many industrial 2 applications. In recent years, the use of positron annihilation spectroscopy (PAS) including 3 positron annihilation lifetime spectroscopy (PALS) and Doppler broadening of annihilation 4 radiation to characterise the internal structure of the skin layer of thin film composite 5 membranes has renewed research interest for further development and optimisation of the RO 6 process. In this article, we highlight the need for better understanding of the skin layer 7 internal structure. We review relevant PAS techniques that could provide an unprecedented 8 level of insight to our understanding of the internal structure of the active skin layer of RO 9 membranes. PALS data reported in previous studies revealed that commercially available RO 10 membranes have a mean free-volume hole-radius of 0.20-0.29 nm in the active skin layer. 11Data corroborated from the literature show a good correlation between the mean free-volume 1...

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Slow Positron Beam Apparatus for Surface and Subsurface Analysis of Samples in Air

Cited by 15 publications

References 16 publications

Free Volume Profiles at Polymer–Solid Interfaces Probed by Focused Slow Positron Beam

Free Volume Profiles at Polymer–Solid Interfaces Probed by Focused Slow Positron Beam

Monte Carlo simulations of the extraction of slow positrons into gas through thin SiN windows

Probing the internal structure of reverse osmosis membranes by positron annihilation spectroscopy: Gaining more insight into the transport of water and small solutes

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