The Experts below are selected from a list of 717075 Experts worldwide ranked by ideXlab platform
Katsuyuki Fukutani - One of the best experts on this subject based on the ideXlab platform.
-
Nuclear Reaction Analysis
Compendium of Surface and Interface Analysis, 2018Co-Authors: Markus Wilde, Katsuyuki FukutaniAbstract:Nuclear Reaction Analysis is a method to quantitatively determine the concentration versus depth distribution of light elements in the near-surface region of solids. To detect a specific nucleus A, the analyzed material is bombarded with a beam of projectile ions (a) at a high energy (100 keV–20 MeV) that is sufficient to overcome the Coulomb repulsion barrier to fuse the nuclei of a and A. Conserving the total energy, the resulting nuclear Reaction A(a,b)B forms a new nucleus B and emits secondary particles (b: protons (p), neutrons (n), 4He ions (‘α particles’) and/or γ-photons) with well-defined high (keV-MeV) energies. The presence of nucleus A in the target is then proven by registering such secondary particles (b) or the Reaction product (B) with a suitable detector.
-
quantification of hydrogen concentrations in surface and interface layers and bulk materials through depth profiling with nuclear Reaction Analysis
Journal of Visualized Experiments, 2016Co-Authors: Markus Wilde, Katsuyuki Fukutani, Shohei Ogura, Satoshi Ohno, Hiroyuki MatsuzakiAbstract:Nuclear Reaction Analysis (NRA) via the resonant (1)H((15)N,αγ)(12)C Reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a (15)N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the (1)H isotope in depths up to about 2 μm from the target surface. Surface H coverages are measured with a sensitivity in the order of ~10(13) cm(-2) (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~10(18) cm(-3) (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal (15)N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth Analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, (1)H((15)N,αγ)(12)C NRA is ideally suited for hydrogen Analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of (15)N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).
-
ir practical extinction coefficients of water in alkali lime silicate glasses determined by nuclear Reaction Analysis
Journal of the American Ceramic Society, 2015Co-Authors: Toshio Suzuki, Junko Konishi, Kiyoshi Yamamoto, Shohei Ogura, Katsuyuki FukutaniAbstract:Infrared spectroscopy (IR) is widely used to determine the water concentration in glasses, whereas determination of the IR practical extinction coefficient is necessary to deduce the absolute water concentration of glasses on the basis of Beer–Lambert law. From the nuclear Reaction Analysis data, the IR practical extinction coefficients of water were successfully determined for the alkali lime silicate glasses with different levels of sodium/potassium cation (Na/K) ratio. The two-band method is well-known to be useful for the determination of the water concentration in some alkali lime silicate glasses. It is proved here that the two-band method is not applicable to the variety of composition for alkali lime silicate and soda lime aluminosilicate glasses, whereas it is valid for the similar composition of soda lime silicate glasses [SLS: Composition (in mol%) 16Na2O·10CaO·74SiO2]. The single-band procedure with the IR practical extinction coefficient is crucial for the determination of the precise water concentration in the wide variety of glass composition although the determination of the IR practical extinction coefficient is troublesome. It also appears that the ion radius of alkali affects the IR practical extinction coefficient and the chemical state of OH group in glasses.
-
hydrogen detection near surfaces and shallow interfaces with resonant nuclear Reaction Analysis
Surface Science Reports, 2014Co-Authors: Markus Wilde, Katsuyuki FukutaniAbstract:Abstract This review introduces hydrogen depth profiling by nuclear Reaction Analysis (NRA) via the resonant 1H(15N,αγ)12C Reaction as a versatile method for the highly depth-resolved observation of hydrogen (H) at solid surfaces and interfaces. The technique is quantitative, non-destructive, and readily applied to a large variety of materials. Its fundamentals, instrumental requirements, advantages and limitations are described in detail, and its main performance benchmarks in terms of depth resolution and sensitivity are compared to those of elastic recoil detection (ERD) as a competing method. The wide range of 1H(15N,αγ)12C NRA applications in research of hydrogen-related phenomena at surfaces and interfaces is reviewed. Special emphasis is placed on the powerful combination of 1H(15N,αγ)12C NRA with surface science techniques of in-situ target preparation and characterization, as the NRA technique is ideally suited to investigate hydrogen interactions with atomically controlled surfaces and intact interfaces. In conjunction with thermal desorption spectroscopy, 15N NRA can assess the thermal stability of absorbed hydrogen species in different depth locations against diffusion and desorption. Hydrogen diffusion dynamics in the near-surface region, including transitions of hydrogen between the surface and the bulk, and between shallow interfaces of nanostructured thin layer stacks can directly be visualized. As a unique feature of 15N NRA, the Analysis of Doppler-broadened resonance excitation curves allows for the direct measurement of the zero-point vibrational energy of hydrogen atoms adsorbed on single crystal surfaces.
-
location of hydrogen adsorbed on rh 111 studied by low energy electron diffraction and nuclear Reaction Analysis
Physical Review B, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh(111) surfaces were investigated by dynamical low-energy electron-diffraction (LEED) Analysis. Exposure of ${\mathrm{D}}_{2}$ induced no additional LEED patterns except for $(1\ifmmode\times\else\texttimes\fi{}1)$. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers $({d}_{12})$ is smaller by $1.2(\ifmmode\pm\else\textpm\fi{}0.6)%$ than the corresponding bulk distance of $2.194\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. On the other hand, the contraction of ${d}_{12}$ is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh(111) was determined to be 0.84 ML by nuclear Reaction Analysis (NRA). Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
Toshio Kasai - One of the best experts on this subject based on the ideXlab platform.
-
location of hydrogen adsorbed on rh 111 studied by low energy electron diffraction and nuclear Reaction Analysis
Physical Review B, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh(111) surfaces were investigated by dynamical low-energy electron-diffraction (LEED) Analysis. Exposure of ${\mathrm{D}}_{2}$ induced no additional LEED patterns except for $(1\ifmmode\times\else\texttimes\fi{}1)$. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers $({d}_{12})$ is smaller by $1.2(\ifmmode\pm\else\textpm\fi{}0.6)%$ than the corresponding bulk distance of $2.194\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. On the other hand, the contraction of ${d}_{12}$ is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh(111) was determined to be 0.84 ML by nuclear Reaction Analysis (NRA). Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
-
Location of hydrogen adsorbed on Rh(111) studied by low-energy electron diffraction and nuclear Reaction Analysis
Physical Review B - Condensed Matter and Materials Physics, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh111 surfaces were investigated by dynamical low-energy electron-diffraction LEED Analysis. Exposure of D2 induced no additional LEED patterns except for 11. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers d12 is smaller by 1.2�0.6% than the corresponding bulk distance of 2.194 �. On the other hand, the contraction of d12 is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh111 was determined to be 0.84 ML by nuclear Reaction Analysis NRA. Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
Masuaki Matsumoto - One of the best experts on this subject based on the ideXlab platform.
-
location of hydrogen adsorbed on rh 111 studied by low energy electron diffraction and nuclear Reaction Analysis
Physical Review B, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh(111) surfaces were investigated by dynamical low-energy electron-diffraction (LEED) Analysis. Exposure of ${\mathrm{D}}_{2}$ induced no additional LEED patterns except for $(1\ifmmode\times\else\texttimes\fi{}1)$. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers $({d}_{12})$ is smaller by $1.2(\ifmmode\pm\else\textpm\fi{}0.6)%$ than the corresponding bulk distance of $2.194\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. On the other hand, the contraction of ${d}_{12}$ is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh(111) was determined to be 0.84 ML by nuclear Reaction Analysis (NRA). Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
-
Location of hydrogen adsorbed on Rh(111) studied by low-energy electron diffraction and nuclear Reaction Analysis
Physical Review B - Condensed Matter and Materials Physics, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh111 surfaces were investigated by dynamical low-energy electron-diffraction LEED Analysis. Exposure of D2 induced no additional LEED patterns except for 11. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers d12 is smaller by 1.2�0.6% than the corresponding bulk distance of 2.194 �. On the other hand, the contraction of d12 is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh111 was determined to be 0.84 ML by nuclear Reaction Analysis NRA. Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
-
influence of h2 annealing on the hydrogen distribution near sio2 si 100 interfaces revealed by in situ nuclear Reaction Analysis
Journal of Applied Physics, 2002Co-Authors: Markus Wilde, Masuaki Matsumoto, Katsuyuki Fukutani, Ziyuan Liu, Koichi Ando, Yoshiya Kawashima, Shinji FujiedaAbstract:Employing hydrogen depth-profiling via 1H(15N,αγ)12C nuclear Reaction Analysis (NRA), the “native” H concentration in thin (19–41.5 nm) SiO2 films grown on Si(100) under “wet” oxidation conditions (H2+O2) was determined to be (1–2)×1019 cm−3. Upon ion-beam irradiation during NRA this hydrogen is redistributed within the oxide and accumulates in a ∼8-nm-wide region centered ∼4 nm in front of the SiO2/Si(100) interface. Annealing in H2 near 400 °C introduces hydrogen preferentially into the near-interfacial oxide region, where apparently large numbers of hydrogen trap sites are available. The amount of incorporated H exceeds the quantity necessary to H-passivate dangling Si bonds at the direct SiO2/Si(100) interface by more than one order of magnitude. The H uptake is strongly dependent on the H2-annealing temperature and is suppressed above 430 °C. This temperature marks the onset of hydrogen desorption from the near-interfacial oxide trap sites, contrasting the thermal stability of the native H, which prevails homogeneously distributed in the SiO2 films after oxidation at 900 °C. Hydrogen bound in the near-interface oxide region is not redistributed by the ion-beam irradiation, further emphasizing its different chemical interaction with the SiO2 network as opposed to the native oxide H. The mechanism of the irradiation-induced H redistribution and its possible relation to the degradation of electrically stressed electronic devices are discussed.
-
nuclear Reaction Analysis of h at the pb si 111 interface monolayer depth distinction and interface structure
Physical Review B, 2001Co-Authors: Katsuyuki Fukutani, Markus Wilde, Masuaki MatsumotoAbstract:Hydrogen atoms buried at the interface between Pb layers and the Si( 111) surface were investigated by resonant nuclear Reaction Analysis (NRA) using 1 H( 1 5 N,αγ) 1 2 C in grazing incidence geometry. Pb atoms were deposited on the H-terminated Si( 111) surface at 110 K, and the H depth was clearly distinguished with a depth scale of one monolayer. The NRA spectrum revealed a monotonous shift to higher energy with increasing Pb coverage indicating H remains at the interface between Pb and the Si substrate. The dependence of the spectral shift on the Pb coverage was found to have an offset corresponding to a depth of about 0.1 I nm. This offset suggests a model for the Pb/H/Si(111) interface structure implying that the initial Pb layer resides in the preadsorbed H layer.
Masayuki Fukuoka - One of the best experts on this subject based on the ideXlab platform.
-
location of hydrogen adsorbed on rh 111 studied by low energy electron diffraction and nuclear Reaction Analysis
Physical Review B, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh(111) surfaces were investigated by dynamical low-energy electron-diffraction (LEED) Analysis. Exposure of ${\mathrm{D}}_{2}$ induced no additional LEED patterns except for $(1\ifmmode\times\else\texttimes\fi{}1)$. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers $({d}_{12})$ is smaller by $1.2(\ifmmode\pm\else\textpm\fi{}0.6)%$ than the corresponding bulk distance of $2.194\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. On the other hand, the contraction of ${d}_{12}$ is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh(111) was determined to be 0.84 ML by nuclear Reaction Analysis (NRA). Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
-
Location of hydrogen adsorbed on Rh(111) studied by low-energy electron diffraction and nuclear Reaction Analysis
Physical Review B - Condensed Matter and Materials Physics, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh111 surfaces were investigated by dynamical low-energy electron-diffraction LEED Analysis. Exposure of D2 induced no additional LEED patterns except for 11. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers d12 is smaller by 1.2�0.6% than the corresponding bulk distance of 2.194 �. On the other hand, the contraction of d12 is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh111 was determined to be 0.84 ML by nuclear Reaction Analysis NRA. Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
Shouhei Ogura - One of the best experts on this subject based on the ideXlab platform.
-
location of hydrogen adsorbed on rh 111 studied by low energy electron diffraction and nuclear Reaction Analysis
Physical Review B, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh(111) surfaces were investigated by dynamical low-energy electron-diffraction (LEED) Analysis. Exposure of ${\mathrm{D}}_{2}$ induced no additional LEED patterns except for $(1\ifmmode\times\else\texttimes\fi{}1)$. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers $({d}_{12})$ is smaller by $1.2(\ifmmode\pm\else\textpm\fi{}0.6)%$ than the corresponding bulk distance of $2.194\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. On the other hand, the contraction of ${d}_{12}$ is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh(111) was determined to be 0.84 ML by nuclear Reaction Analysis (NRA). Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
-
Location of hydrogen adsorbed on Rh(111) studied by low-energy electron diffraction and nuclear Reaction Analysis
Physical Review B - Condensed Matter and Materials Physics, 2007Co-Authors: Masayuki Fukuoka, Shouhei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani, Michio Okada, Toshio KasaiAbstract:The structures of clean and hydrogen-adsorbed Rh111 surfaces were investigated by dynamical low-energy electron-diffraction LEED Analysis. Exposure of D2 induced no additional LEED patterns except for 11. Surface-layer relaxation occurs vertically on both clean and D-saturated surfaces. On the clean surface, the interlayer distance between the first and second layers d12 is smaller by 1.2�0.6% than the corresponding bulk distance of 2.194 �. On the other hand, the contraction of d12 is removed on the D-saturated surface. Detailed LEED Analysis demonstrates that the D atoms are adsorbed on the fcc threefold hollow sites. The absolute saturation coverage of H on Rh111 was determined to be 0.84 ML by nuclear Reaction Analysis NRA. Moreover, the zero-point vibrational energy of H was derived from the Analysis of the NRA resonance profile, which is discussed in comparison with the results of high-resolution electron-energy-loss spectroscopy.
