Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 124

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Analysis of gadolinium oxide using microwave-enhanced fiber-coupled micro-laser-induced breakdown spectroscopy

Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo

Scientific Reports (Internet), 13, p.4828_1 - 4828_9, 2023/03

 Times Cited Count:0 Percentile:99.08(Multidisciplinary Sciences)

Journal Articles

Doppler-free ablation fluorescence spectroscopy of Ca for high-resolution remote isotopic analysis

Miyabe, Masabumi; Kato, Masaaki*; Hasegawa, Shuichi*

Journal of Analytical Atomic Spectrometry, 38(2), p.347 - 358, 2023/02

 Times Cited Count:0 Percentile:0.02(Chemistry, Analytical)

To develop remote isotopic analysis for the nuclids with small isotope shifts, Doppler-free fluorescence spectroscopy of Ca was performed using laser ablation plume. Counter-propagating laser beams from two external cavity diode lasers were used to irradiate the plume in order to excite the ground-state Ca atoms to the $$^{1}$$D$$_{2}$$ state through a double resonance scheme of $$^{1}$$S$$_{0}$$ $$rightarrow$$ $$^{1}$$P$$_{1}$$ $$rightarrow$$ $$^{1}$$D$$_{2}$$. Subsequently, we measured fluorescence spectra associated with the relaxation from the $$^{1}$$D$$_{2}$$ to $$^{1}$$P$$_{1}$$ states. The linewidth measured at 1 ms delay after ablation under helium gas pressure of 70 Pa was found to be less than 70 MHz, which was about 1/30 of the linewidth of the Doppler-limited fluorescence spectrum. A broad Gaussian pedestal was observed at less than 600 micro-second delay in the temporal variation in fluorescence spectra, and it was most likely due to the velocity-changing collision. Additionally, the pressure broadening rate coefficient for the second-step $$^{1}$$P$$_{1}$$$$rightarrow$$ $$^{1}$$D$$_{2}$$ transition was determined to be 46.0 MHz/torr from the spectra measured under various gas pressures. We evaluated analytical performances such as linearity of the calibration curve, limit of detection, and measurement accuracy using fluorescence signals of three naturally occurring Ca isotopes (i.e., $$^{40}$$Ca, $$^{42}$$Ca, and $$^{44}$$Ca). The limit of detection of isotopic abundance was estimated to be 0.09% from the 3-sigma criteria of the background. These results suggest that this spectroscopic technique is promising for remote isotopic analysis of nuclides with small isotope shifts.

Journal Articles

Isotope shift and hyperfine structure measurements on triple resonance excitation to the autoionizing Rydberg state of atomic strontium

Iwata, Yoshihiro; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo

Journal of Quantitative Spectroscopy & Radiative Transfer, 275, p.107882_1 - 107882_9, 2021/11

 Times Cited Count:3 Percentile:39.43(Optics)

Following the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, an isotope-selective analysis method using laser resonance ionization has been developed for strontium-90. In this study, the isotope shifts and hyperfine structure constants of stable isotopes were measured for two schemes expected to have high isotopic selectivity, and the isotope shifts of strontium-90 were evaluated using the King plot analysis. The measured strontium-90 optical isotopic selectivities ranged from $$10^3$$ to $$10^5$$, which are sufficient for analysis of real samples.

Journal Articles

Odd-parity autoionizing levels of uranium observed by two-color two-step photoionization optogalvanic spectroscopy

Miyabe, Masabumi; Satou, Yukihiko; Wakaida, Ikuo; Terabayashi, Ryohei*; Sonnenschein, V.*; Tomita, Hideki*; Zhao, Y.*; Sakamoto, Tetsuo*

Journal of Physics B; Atomic, Molecular and Optical Physics, 54(14), p.145003_1 - 145003_8, 2021/07

 Times Cited Count:0 Percentile:0.01(Optics)

Two-color two-step photoionization optogalvanic spectroscopy was performed using high-repetition-rate titanium sapphire lasers and a uranium hollow cathode lamp to find the two-step resonance ionization schemes of uranium. Many ionization transitions were observed by exciting uranium atoms in a ground state into five, even parity, excited levels with the first-step laser and by scanning the second-step laser wavelengths. By blocking the first-step laser, single-color, two-photon ionization transitions were also identified. From these results, we have found more than 50 odd-parity autoionizing levels of uranium in the energy, ranging from the ionization potential (49958.4 cm$$^{-1}$$) to 51150 cm$$^{-1}$$. The determined energy levels are within 1 cm$$^{-1}$$ of previously reported values.

Journal Articles

Investigation on the DC Stark shifts of strontium autoionization states for isotope-selective resonance ionization

Iwata, Yoshihiro; Miyabe, Masabumi; Hasegawa, Shuichi*

Journal of Quantitative Spectroscopy & Radiative Transfer, 265, p.107549_1 - 107549_7, 2021/05

 Times Cited Count:1 Percentile:13.5(Optics)

Following the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, an isotope-selective analysis method using laser resonance ionization has been developed for strontium-90. In this study, we focused on ionization via autoionization states in terms of high isotopic selectivity and ionization efficiency, and the DC Stark shifts caused by the external electric field were measured for these states. It was found that the external electric field in the ionization region has to be of the order of 0.1 V/cm or less to suppress its effect on the observed spectra.

Journal Articles

Highly sensitive detection of sodium in aqueous solutions using laser-induced breakdown spectroscopy with liquid sheet jets

Nakanishi, Ryuzo; Oba, Hironori; Saeki, Morihisa; Wakaida, Ikuo; Tanabe, Rie*; Ito, Yoshiro*

Optics Express (Internet), 29(4), p.5205 - 5212, 2021/02

 Times Cited Count:10 Percentile:84.06(Optics)

Laser-induced breakdown spectroscopy (LIBS) combined with liquid jets was applied to the detection of trace sodium (Na) in aqueous solutions. The sensitivities of two types of liquid jets were compared: a liquid cylindrical jet with a diameter of 500 $$mu$$m and a liquid sheet jet with a thickness of 20 $$mu$$m. Compared with the cylindrical jet, the liquid sheet jet effectively reduced the splash from the laser-irradiated surface and produced long-lived luminous plasma. The limit of detection (LOD) of Na was determined to be 0.57 $$mu$$g/L for the sheet jet and 10.5 $$mu$$g/L for the cylindrical jet. The LOD obtained for the sheet jet was comparable to those obtained for commercially available inductively coupled plasma emission spectrometers.

Journal Articles

Development of laser ablation absorption spectroscopy for nuclear fuel materials; Plume expansion behavior for refractory metals observed by laser-induced fluorescence imaging spectroscopy

Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Kato, Masaaki*; Hasegawa, Shuichi*; Wakaida, Ikuo

Applied Physics A, 126(3), p.213_1 - 213_10, 2020/03

AA2019-0700.pdf:2.82MB

 Times Cited Count:5 Percentile:39.72(Materials Science, Multidisciplinary)

The dynamic behavior of an ablation plume in low pressure rare gas ambient was investigated with laser-induced fluorescence imaging spectroscopy for three refractory metals, i.e. titanium, zirconium and hafnium. A comparison of the plume expansion behaviors for the species of these elements revealed an atomic weight effect on the plume structure formation. A hemispherical thin layer and cavity structure reported previously for gadolinium were observed also for these elements. It was found that the plume size increases as well as the layer thickness decreases with increasing atomic weight. For ground state atoms of Ti, substantial amount of atoms were observed even at the center of the plume. Also, the persistence of the Ti atomic plume was as long as 300 $$mu$$s, which was significantly longer than the other species studied. Furthermore, the mass-dependent elemental separation was observed in the ablation plume produced from a multielement sample. These results suggest that the observed plume structure arises from the ion-electron recombination process and the recoil of the ablated species during the multiple collisions with gas atoms.

Journal Articles

Laser-induced breakdown spectroscopy and related resonance spectroscopy for nuclear fuel cycle management and for decommissioning of "Fukushima Daiichi Nuclear Power Station"

Wakaida, Ikuo; Oba, Hironori; Miyabe, Masabumi; Akaoka, Katsuaki; Oba, Masaki; Tamura, Koji; Saeki, Morihisa

Kogaku, 48(1), p.13 - 20, 2019/01

By Laser Induced Breakdown Spectroscopy and by related resonance spectroscopy, elemental and isotope analysis of Uranium and Plutonium for nuclear fuel materials and in-situ remote analysis under strong radiation condition for melt downed nuclear fuel debris at damaged core in "Fukushima Daiichi Nuclear Power Station", are introduced and performed as one of the application in atomic energy research field.

Journal Articles

Effect of defocusing on laser ablation plume observed by laser-induced fluorescence imaging spectroscopy

Oba, Masaki; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo

Japanese Journal of Applied Physics, 55(2), p.022401_1 - 022401_4, 2016/02

 Times Cited Count:3 Percentile:15.07(Physics, Applied)

We used laser-induced fluorescence imaging with a varying beam focal point to observe ablation plumes from metal and oxide samples of gadolinium. The plumes expand vertically when the focal point is far from the sample surface. In contrast, the plume becomes hemispherical when the focal point is on the sample surface. In addition, the internal plume structure and the composition of the ablated atomic and ionic particles also vary significantly. The fluorescence intensity of a plume from a metal sample is greater than that from an oxide sample, which suggests that the number of monatomic species produced in each plume differs. For both the metal and oxide samples, the most intense fluorescence from atomic (ionic) species is observed with the beam focal point at 3-4 mm (2 mm) from the sample surface.

Journal Articles

Ablation plume structure and dynamics in ambient gas observed by laser-induced fluorescence imaging spectroscopy

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Khumaeni, A.*; Kato, Masaaki; Wakaida, Ikuo

Spectrochimica Acta, Part B, 110, p.101 - 117, 2015/08

AA2015-0183.pdf:3.11MB

 Times Cited Count:25 Percentile:82.24(Spectroscopy)

The dynamic behavior of an ablation plume in ambient gas has been investigated by laser-induced fluorescence imaging spectroscopy. The second harmonic beam from an Nd:YAG laser (0.5-6J/cm$$^{2}$$) was focused on a sintered oxide pellet or a metal chip of gadolinium. The produced plume was subsequently intersected with a sheet-shaped UV beam from a dye laser so that time-resolved fluorescence images were acquired with an intensified CCD camera at various delay times. The obtained cross-sectional images of the plume indicate that the ablated ground state atoms and ions of gadolinium accumulate in a hemispherical contact layer between the plume and the ambient gas, and a cavity containing a smaller density of ablated species is formed near the center of the plume. At earlier expansion stage, another luminous component also expands in the cavity so that it coalesces into the hemispherical layer. The splitting and coalescence for atomic plume occur later than those for ionic plume. Furthermore, the hemispherical layer of neutral atoms appears later than that of ions; however, the locations of the layers are nearly identical. This coincidence of the appearance locations of the layers strongly suggests that the neutral atoms in the hemispherical layer are produced as a consequence of three-body recombination of ions through collisions with gas atoms. The obtained knowledge regarding plume expansion dynamics and detailed plume structure is useful for optimizing the experimental conditions for ablation-based spectroscopic analysis.

Journal Articles

Identification of asbestos by laser-induced fluorescence microscopy

Ozu, Akira; Esaka, Fumitaka; Yasuda, Kenichiro

Bunseki Kagaku, 60(1), p.75 - 80, 2011/01

 Times Cited Count:0 Percentile:0(Chemistry, Analytical)

Microscopic studies on laser-induced fluorescence emitted from asbestos (chrysotile) and a building material (glass-wool: a substitute material for asbestos) fibrous particle excited by a ultra-violet (266 nm) laser, have been conducted by visualizing those particles with the fluorescence. The fluorescence characteristics observed under the microscope agreed approximately with those observed in the determination using bulk samples. The decay ratio of the fluorescence intensity at 540 nm and other wavelength was in good agreement with that with bulk sample. The total amount of the intensity of glass-wool per unit area at $$>$$ 350 nm was 23 times larger than that of chrysotile, corresponding to that with bulk sample. A practical microscopic method used to discriminate asbestos by combining the decay ratio and total amount of the intensity are proposed.

Journal Articles

Feasibility study on identification of asbestos using laser-induced fluorescence

Ozu, Akira; Esaka, Fumitaka; Yasuda, Kenichiro

Bunseki Kagaku, 58(6), p.569 - 576, 2009/06

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

Laser-induced fluorescence of asbestos and several kinds of building materials such as glass-wools and talc, etc., have been studied for discriminating asbestos from the other materials. The fluorescence spectrums excited by ultra-violet (266 nm) laser pulse were observed over the wavelength range 350 to 700 nm, and the difference of the spectrum in shape between asbestos and the other materials was identified. The lifetime and relative intensity of the fluorescence emitted from those materials were also investigated and evaluated for the numerical discrimination of asbestos. Novel methods are presented for discriminating asbestos by comparing the relative ratio of the fluorescence intensity between two different ranges (430 and 575 nm) of the wavelength, and/or the lifetime and the total amount of the fluorescence. Applications of the method to conventional particle measurement systems, as examples, a microscopic method and an optical particle counter, are discussed.

Journal Articles

Time-resolved laser-induced fluorescence of asbestos in visible region

Ozu, Akira; Esaka, Fumitaka; Yasuda, Kenichiro

Japanese Journal of Applied Physics, 48(4), p.042303_1 - 042303_5, 2009/04

 Times Cited Count:4 Percentile:18.61(Physics, Applied)

Nanosecond time-resolved laser-induced fluorescence spectroscopy was performed on five kinds of asbestos materials (chrysotile, crocidolite, amosite, tremolite and anthophyllite) using a ultra-violet laser pulse of 266 nm. Most of the fluorescence spectra had a broad wavelength band of 350-700 nm and a maximum near around 450 nm in the visible region. The spectra also varied in shape over time. Although all the spectra were similar in shape, a significant difference in the relative ratio of fluorescence intensity between the two different wavelength regions was identified. The lifetime and total amount of fluorescence intensity were also investigated and the differences were observed for the different kinds of asbestos. Several methods potentially useful for discriminating asbestos from other materials through use of their fluorescence characteristics are discussed.

JAEA Reports

Emission characteristics of copper plasma in laser-induced breakdown spectroscopy (Contract research)

Maruyama, Yoichiro; Wakaida, Ikuo

JAEA-Technology 2008-051, 13 Pages, 2008/07

JAEA-Technology-2008-051.pdf:2.07MB

Plasma emission characteristics of copper were studied by using Laser-Induced Breakdown Spectroscopy (LIBS). The intensity of plasma emission depended on the species of atmospheric gases, and the strongest plasma emission was obtained in the Ar atmosphere. And it was observed that the intensity reached its maximum at 1-2 microseconds after the ablation and decreased. The spectrum broadening due to Stark effect was observed and the spectral width varied with the observed time and the atmospheric gases, and the narrowest spectral width was obtained in He atmosphere. The plasma temperature calculated from spectral intensities reached around 10,000 K at 1-2 microseconds after the ablation and increased with increasing ablation laser energy.

Journal Articles

Selective detection of aerosol particles using remote particle counter

Ozu, Akira

Kurin Tekunoroji, 17(7), p.54 - 57, 2007/07

A method for the selective detection of aerosol particles consisting of a specified substance has been demonstrated by using laser-induced fluorescence. A remote particle counter developed for the remote monitoring of aerosol particles was applied to visualize laser-induced fluorescence emitted from a specific aerosol particles. It is made of a Q-switched Nd:YAG laser, a CCD camera equipped with a fast gate shutter, and a personal computer. An optical low-pass filter equipped with the camera can transmit the laser-induced fluorescence and eliminate the backscattered laser light from particles. The method was applied to detect alcohol mist aerosol in which a laser dye is dissolved and asbestos particles suspended in air. This method is expected to be useful for measuring selectively the number of a specific aerosol.

Oral presentation

Development of trace analysis on Ca isotopes using resonance ionization mass spectrometry

Miyabe, Masabumi; Oba, Masaki; Wakaida, Ikuo; Kato, Masaaki; Watanabe, Kazuo

no journal, , 

no abstracts in English

Oral presentation

Development of laser remote analysis for nuclear fuel materials, 2; Breakdown characteristics and the effect of double pulse irradiation of LIBS

Oba, Masaki; Maruyama, Yoichiro; Akaoka, Katsuaki; Miyabe, Masabumi; Wakaida, Ikuo

no journal, , 

The irradiation characteristics of the Cu metal as dummy nuclear fuel materials were measured by double pulse LIBS. In this measurement, signal was enhanced compared with single pulse LIBS.

Oral presentation

Asbestos discrimination based on spectral analysis of laser-induced fluorescence

Ozu, Akira; Esaka, Fumitaka; Yasuda, Kenichiro

no journal, , 

Laser-induced fluorescence of three kinds of asbestos, fibrous building materials, and non-fibrous building materials were studied for asbestos discrimination. Lifetimes and relative intensity of the fluorescence from those materials excited by ultra-violet pulse laser of 266 nm were investigated. It was observed that the fluorescence of those materials was nearly made of two lifetimes (short and long) and the lifetime was changed with measured wavelength. The total amount of the fluorescence from chrysotile was around 10 times larger than that of crocidolite and amosite, and far smaller (1/45) than that of glass wool. Significant difference of the lifetime and intensity among those materials was identified. The discrimination methods using the difference of the decay ratio of the fluorescence intensity and the total amount of the fluorescence are discussed and the applications of those methods for microscopic analysis and optical particle measurement system are presented.

Oral presentation

Development of laser remote analysis; Basic characteristics in impurity analysis of uranium oxide by Laser Induced Breakdown Spectroscopy (LIBS), 2

Wakaida, Ikuo; Akaoka, Katsuaki; Oba, Masaki; Maruyama, Yoichiro; Miyabe, Masabumi; Otobe, Haruyoshi; Kato, Masaaki; Niki, Hideaki*

no journal, , 

Basic study of the quick, simple and onsite remote analysis without chemical separation is required for the analysis of Low-decontaminated TRU fuel for FBR of the next generation. LIBS will be one of the useful techniques for the remote analysis, and we are studying about the emission characteristics such as time-spatial phenomenon and laser power dependence in the uranium oxide contained with calcium impurity. The influence by the change of plasma temperature will be able to control by the selection of the emission energy level. The strength of the impurity emission is estimated by the deconvolution technique and calibration characteristic is obtained. By the comparison with the standard deviation, the detection limit of 70 ppm ($$sigma$$) in the impurity analysis of uranium oxide fuel will be determined.

Oral presentation

Development of laser remote analysis for nuclear fuel materials, 2-5; Study on plume dynamics by resonance imaging spectroscopy

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Hironori; Tampo, Motonobu; Wakaida, Ikuo

no journal, , 

We investigate dynamic behavior of ablation plume produced in background gas for nondestructive remote isotope analysis for a next-generation fuel. From our previous studies, it is expected that most of the ablated particles are concentrated on the surface of the plume in helium gas, and there is a cavity where few particles exists close to the ablation spot. In the present study actually we observed such plume structure using the laser-induced fluorescence images of Gd atoms and ions. It was also found that the minimum thickness of the layer where neutral atoms were concentrated was less than 0.5mm and the positions of the atomic layer was very close to that of ionic layer. From this observation, the neutral atoms are more likely to be produced as a result of recombination of the ions and electrons. The knowledge of the plume structure is thought be of importance in optimizing the experiment conditions for ablation analysis.

124 (Records 1-20 displayed on this page)