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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 D state through a double resonance scheme of S P D. Subsequently, we measured fluorescence spectra associated with the relaxation from the D to P 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 P D 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., Ca, Ca, and 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.
Miyabe, Masabumi; Oba, Masaki; Akaoka, Katsuaki; Kato, Masaaki*; Hasegawa, Shuichi*; Wakaida, Ikuo
Applied Physics A, 126(3), p.213_1 - 213_10, 2020/03
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 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.
Miyabe, Masabumi; Oba, Masaki; Jung, K.; Iimura, Hideki; Akaoka, Katsuaki; Kato, Masaaki; Otobe, Haruyoshi; Khumaeni, A.*; Wakaida, Ikuo
Spectrochimica Acta, Part B, 134, p.42 - 51, 2017/08
Times Cited Count:28 Percentile:91.14(Spectroscopy)Spectroscopic properties of atomic species of plutonium were investigated by combining laser ablation and resonance absorption techniques for the analysis of a plutonium oxide sample. For 17 transitions of Pu atoms and ions, the absorbance, isotope shift, and hyperfine splitting were determined via Voigt profile fitting of the recorded absorption spectra. Three transitions were selected as candidates for analytical use. Using these transitions, we investigated the analytical performance that was attainable and determined a correlation coefficient R2 between the absorbance and plutonium concentration of 0.9999, a limit of detection of 30-130 ppm, and a relative standard deviation of approximately 6% for an abundance of Pu of 2.4%. These results demonstrate that laser ablation absorption spectroscopy is applicable to the remote isotopic analysis of highly radioactive nuclear fuels and waste materials containing multiple actinide elements.
Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Khumaeni, A.*; Kato, Masaaki; Wakaida, Ikuo
Spectrochimica Acta, Part B, 110, p.101 - 117, 2015/08
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) 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.
Miyabe, Masabumi; Kato, Masaaki; Oba, Masaki; Wakaida, Ikuo; Watanabe, Kazuo; Wendt, K.*
Japanese Journal of Applied Physics, Part 1, 45(5A), p.4120 - 4122, 2006/05
Times Cited Count:2 Percentile:8.74(Physics, Applied)We developed a frequency-stabilized diode laser using magnetically induced circular dichroism. From a spectroscopic study on Rb- line, the most stable Doppler-broadened and Doppler-free lines were determined to be the transition from g=2 ground state of Rb and the crossover resonance from g=3 ground state to e=3 and 4 excited states of Rb respectively. Furthermore, we measured the fluctuation of the laser locked to the Doppler-free line to be 50kHz/8hour and thus revealed the applicability to a several-hours stabilization. The developed laser can be used as a reference laser for frequency stabilization system for multiple tunable lasers for RIMS analysis.
Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
Journal of Nuclear Science and Technology, 43(4), p.305 - 310, 2006/04
Times Cited Count:13 Percentile:65.92(Nuclear Science & Technology)We are developing an resonance ionization spectrometric apparatus aiming at an analysis of a radioactive isotope of calcium (Ca) in nuclear waste materials. The developed system consists of the reference laser whose frequency was locked on a Doppler-free absorption line of 85Rb and the computer-controlled fringe offset lock system which transfer frequency stability of the reference laser to slave lasers for Ca excitation. With heterodyne spectroscopy and laser induced fluorescence spectroscopy of Ca, it was confirmed that the developed apparatus was suitable for resonance ionization spectrometric analysis.
Miyabe, Masabumi; Geppert, C.*; Kato, Masaaki; Oba, Masaki; Wakaida, Ikuo; Watanabe, Kazuo; Wendt, K. D. A.*
Journal of the Physical Society of Japan, 75(3), p.034302_1 - 034302_10, 2006/03
Times Cited Count:17 Percentile:66.04(Physics, Multidisciplinary)High-resolution resonance ionization spectroscopy has been utilized to determine a precise ionization potential of Ca. Three-step resonance excitation with single-mode extended cavity diode lasers populates long and unperturbed Rydberg series of 4snp (1P1) and 4snf (1F3) states in the rage of n=20-150. By using an extended Ritz formula for quantum defect, the series convergence limit has been determined to be 49305.9240 (20) cm with the accuracy improved one order of magnitude higher than previously reported ones.
Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
JAERI-Tech 2005-043, 27 Pages, 2005/08
Multi-step resonance ionization spectrometry for long-lived nuclei in nuclear waste materials requires laser sources having high frequency stability and tunability. In this study we have developed a novel frequency control system consisting of digital circuitry and computer to improve the frequency tunability of the developed laser stabilization system using dichroic atomic vapor laser lock (DAVLL) and fringe offset lock (FOL) techniques. Based on the heterodyne experiment and multi-step laser induced fluorescence spectroscopy of atomic Ca, the frequency stability and tunability of the developed system were evaluated.
Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
JAERI-Research 2004-023, 17 Pages, 2004/11
High precision resonance ionization spectroscopy has been applied to determination of an accurate ionization potential of Ca. Three-step resonant excitation with single-mode extended cavity diode lasers populates a series of (P) and (F) Rydberg states in the rage of =20-150. By using an extended Ritz formula for quantum defect, the series convergence limit has been determined to be 49305.9240 (20) cm with the accuracy improved one order of magnitude higher than previously reported ones.
Miyabe, Masabumi; Kato, Masaaki; Oba, Masaki; Wakaida, Ikuo; Watanabe, Kazuo
JAERI-Tech 2004-065, 19 Pages, 2004/10
In nuclear waste materials there are various radionuclides to which standard analytical techniques are difficult to be applied. We are developing an analytical technique where such nuclides are ionized and mass-analyzed using diode laser based multi-step RIMS technique. The diode laser, however, has one drawback, i.e. its oscillation wavelength is readily drifted by acoustic, electric and optical noise, and thus the laser without frequency stabilization is not suitable for the analysis. In this study, we have developed (1) the diode laser whose frequency is stabilized to an intense absorption line of Rb by Zeeman effect and (2) the stabilization system where diode lasers for 3-step ionization of Ca are locked to the Rb-stabilized laser using a Fabry-perot interferometer. Additionally, to evaluate overall frequency stability of the stabilization system, fluctuations in the photoion and fluorescence signals arising from 3-step RIMS of Ca were simultaneously observed.
Miyabe, Masabumi; Oda, Koichi*; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo
JAERI-Tech 2004-064, 33 Pages, 2004/10
In nuclear waste materials there are various radionuclides to which standard analytical techniques are difficult to be applied. We are developing an analytical technique where such nuclides are analyzed using multi-step resonance ionization mass spectrometry. In this study, we have developed an external cavity diode laser applicable to the analysis. The wavelength and output power dependence on injection current and temperature were investigated for various types of laser diodes. Based on the data, we have obtained a suitable condition to operate the ECDL in stable single-mode oscillation, so that a continuous scanning range of about 100 GHz was realized. Additionaly, to evaluate the bandwidth of the developed ECDL, we have performed Doppler-free spectroscopy. The reasonable agreement of the measured isotope shift and HFS splitting with the reported values demonstrated that the developed ECDL is applicable to a precise laser spectroscopy as well as a laser trace analysis.
Maruyama, Yoichiro; Kato, Masaaki
JAERI-Research 2002-040, 15 Pages, 2003/02
As a tunable laser source for the study of real time LIDAR techique to detect some trace impurities in atmosphere, a dye laser has been employed. As a dye laser is difficult to handle, it is considered that the dye laser may not be used as a practical light source. A tunable solid stat laser composed of an optical parametricc oscillaotr (OPO) which has a wider wavelength range is one of the promising tunable light sources, however, there is no OPO with high repetition rate and large pulse energy. Therefore high repetition rate lasing characteristics of OPO are studied. In this experiment, -Barium Borate (BBO) crystal is utilized as a gain meduim of OPO and pumped by the second harmonic of Nd:YAG laser with the pulse repetition rate of 0.5 kHz. The threshold pumping peak power for BBO-OPO is around 16 MW/cm. Maximum OPO average output power of around 5.4 W is obtained with the power conversion efficiency of around 45%. The averege output power of OPO is increasing with the pumping power and undesirable thermal effects are not observed.
Oba, Masaki; Kato, Masaaki; Maruyama, Yoichiro
Japanese Journal of Applied Physics, Part 2, 41(8A), p.L881 - L883, 2002/08
Times Cited Count:0 Percentile:0(Physics, Applied)Optical parametric oscillator using a periodically poled KTP as a gain medium pumped by a pulsed Nd:YAG green laser of which maximum pulse repetition frequency is 100 Hz is demonstrated. Output energy of 5.8 mJ at the pulse repetition frequency of 100 Hz with the conversion efficiency of about 40% is obtained by double-pass pumping scheme. Threshold pumping energy is 1.6 mJ of which peak power is as low as 18 MW/cm. At the pulse repetition frequency between 10 Hz and 100 Hz, the conversion efficiency is almost constant and undesirable thermal effects are not observed.
Maruyama, Yoichiro; Oba, Masaki; Kato, Masaaki
JAERI-Tech 2002-004, 13 Pages, 2002/02
For the in-situ measurement of various substances in the atmosphere by using DIAL (Differential Absorption LIDAR) , a high repetition rate tunable laser is required to obtain data within a few seconds. As the pump source of the tunable laser, the performance of high repetition rate and high average power is indispensable. For the generation of high quality laser radiation, a laser oscillator with 1 kHz pulse repetition rate is made and seeded with very narrow linewidth single-longitudinal mode laser radiation from the outside of the oscillator cavity and its characteristics are studied. As the results, after the thermal equilibrium of the oscillator laser crystal, a single-longitudinal and near TEMoo transverse mode are realized at the pulse repetition rate between 0.5kHz and 1kHz. Single frequency operation is preserved by controlling the cavity length. The average output power of 3W (3mJ per pulse) is obtained. It is confirmed that this oscillator has enough performance as a oscillator of MOPA (Master Oscillator Power amplifier) system.
Maruyama, Yoichiro; Kato, Masaaki; Ozu, Akira
Optical Pulse and Beam Propagation III (Proceedings of SPIE Vol.4271), p.335 - 338, 2001/01
no abstracts in English
Ozu, Akira; Kato, Masaaki; Maruyama, Yoichiro
Japanese Journal of Applied Physics, Part 1, 39(9A), p.5118 - 5123, 2000/09
Times Cited Count:2 Percentile:12.65(Physics, Applied)no abstracts in English
Ozu, Akira; Kato, Masaaki; Maruyama, Yoichiro
Review of Scientific Instruments, 71(6), p.2288 - 2291, 2000/06
Times Cited Count:2 Percentile:26.97(Instruments & Instrumentation)no abstracts in English
Ozu, Akira; Kato, Masaaki; Maruyama, Yoichiro
Applied Physics Letters, 76(21), p.2979 - 2981, 2000/05
Times Cited Count:9 Percentile:41.42(Physics, Applied)no abstracts in English
Ozu, Akira; Kato, Masaaki; Maruyama, Yoichiro
Optics Communications, 177(1-6), p.355 - 361, 2000/04
Times Cited Count:4 Percentile:26.56(Optics)no abstracts in English
Tei, Kazuyoku; Matsuoka, Fumiaki*; Kato, Masaaki; Maruyama, Yoichiro; Arisawa, Takashi
Optics Letters, 25(7), p.481 - 483, 2000/04
Times Cited Count:14 Percentile:57.24(Optics)no abstracts in English