記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

We have developed a technology for producing nonagglomerated nanoparticles by causing collisions of the agglomerates in supersonic flows. To form these nonagglomerated nanoparticles, we conducted three experiments: the collision of agglomerated particles in a supersonic flow with a metal plate, the collision of agglomerated particles contained in two counter-current supersonic flows, and the collision of agglomerated particles in a supersonic flow with dry ice particles. The possibility that these collisions could fragment the agglomerates was investigated by measuring the size distribution of the agglomerates after the collisions using a differential mobility analyzer. Based on the experimental results, we propose that the most efficient technology for the fragmentation of the agglomerates depends on the concentration of the agglomerates. When the concentration is high, two counter-current supersonic flows containing the agglomerates should be used. When the concentrations are low, collision of agglomerates with dry ice particles should be performed.

DOI： 10.1252/jcej.14we143

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

The formation of non-aggregated nickel nanoparticles by hydrogen reduction of nickel chloride has been studied in a tubular furnace reactor. A change in the proportion of non-aggregated particles in TEM images was observed using a rapid cooling of the entire aerosol produced in the reactor with jets of N-2 quenching gas and a Laval nozzle placed above the reactor. The proportion of non-aggregated particles was 38% for nickel particles produced without any cooling steps. When the aerosol was supercooled in the Laval nozzle after passing the jets of N-2 quenching gas, the proportion of non-aggregates was as large as 84%. It was found that the rapid cooling in the region downstream of the reactor is quite effective for preventing aggregation of particles.

DOI： 10.1252/jcej.13we268

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記述言語：英語   掲載種別：研究論文（大学，研究機関等紀要）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

We have developed a technology for the production of non-agglomerated nanoparticles by collisions of agglomerates in supersonic flows. To form non-agglomerated nanoparticles, we conducted the following three experiments: the collision of agglomerated particles in the supersonic flow with a fixed metal plate, the collision of agglomerates in the supersonic flow with a vibrating metal plate, and the counter-collision of two supersonic flows containing agglomerated particles. The probability of the fragmentation of agglomerates by means of the collisions was investigated by counting the number of non-agglomerated particles and agglomerated particles in TEM images. The results of the experiments revealed that the collision of agglomerates with a plate generates the problem of particles remaining on the metal plate even under low-collision velocity, and the counter-collision of two supersonic flows containing agglomerated particles induces the highly efficient fragmentation of agglomerates.

DOI： 10.1252/jcej.13we044

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

In microreactors, which comprise extremely narrow channels, a fluid is in laminar flow. The flow is constant spatially and temporally, and therefore, reactant concentrations are defined spatially, resulting in constant reactions. Consequently, the concentrations of reaction intermediates generated in microreactors are also defined spatially and are always constant. Regulation of the concentrations of the reaction intermediates enables efficient control of the reactions. In the present study, we have developed a basic technique for reaction control in microreactors by Raman microscopic spectrometry, and showed that the concentrations of the reaction intermediates are spatially defined as unique values that are dependent on the reactant concentration.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

The formation of non-agglomerated titania particles by oxidation of titanium-tetra-isopropoxide (TTIP) has been studied in a methane/oxygen coflow diffusion-flame reactor. A change in the proportion of virtually non-agglomerated particles in TEM images was observed using a rapid cooling of the entire flame aerosol with a blow of cold Ar quenching gas and supercooling in a Laval nozzle placed above the flame. The proportion of non-agglomerates was 25% for TiO2 particles produced without any cooling steps. When the quenching gas of 25 L/min Ar cooled at -70 degrees C blew on the tip of the flame, the proportion of non-agglomerates was 70%. When the flame aerosol was supercooled in the Laval nozzle after blowing -70 degrees C Ar quenching gas, a decrease in the aerosol temperature was induced from approximately 1500 to 300 degrees C in 0.9 ms and, as a result, the proportion of non-agglomerates was as large as 90%. It was found that the rapid cooling in the region of the flame tip is quite effective for preventing agglomeration.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC APPLIED PHYSICS  

We precisely measured the electrical mobilities of C-60 negative ions (1.0 nm in outer diameter) using a differential mobility analyzer in helium, neon, argon, and krypton at pressures ranging from 1.07 x 10(4) to 4.40 x 10(4) Pa. The measured inverse mobilities were larger than those calculated from the hard-sphere collision model. We proposed a formula describing the relation between the electrical mobilities and the diameter of C-60 ions in such noble gases, which compensates for the deviation from the hard-sphere collision model.

DOI： 10.1143/JJAP.47.5684

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

Poly(amidoamine) (PAMAM) dendrimers generations 2 through 6 were aerosolized by an electrospray aerosol generator and their electrical mobility spectra observed using a differential mobility analyzer (DMA). We succeeded in measuring the electrical mobilities of the monomer and dimer ions of these dendrimers. The experimental results suggested that PAMAM dendrimers are useful as standard particles in the range of a few nanometers. (C) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jaerosci.2006.05.005

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC APPLIED PHYSICS  

An anomalous behavior was found in the electrical mobilities,of C-60 negative ions in He, Ne, and Ar gas measured using a differential mobility analyzer (DMA). The measured inverse mobilities were larger than those calculated with a hard-sphere collision model. We suggested that this anomalous behavior could be ascribed to the potential force of interactions between the C-60 negative ion and the gas molecule. Additionally, a method of ab initio calculation of potential energies between the C-60 negative ion and the sheath gas molecule was developed, to quantitatively understand the anomalous behavior.

DOI： 10.1143/JJAP.45.7243

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

A new dual-type differential mobility analyzer (dual-type DMA) was developed in order to detect transient number concentrations of airborne nanoparticles with diameters centralized at around 10 nm (for nuclei mode particles) and 100 nm (for accumulation mode particles) in automobile exhaust gas. The apparatus divides the gas sample into two parts, and each part is sent through one of two coaxially nested sections for analysis. For the scanning mode measurement, the nanoparticles are charged by Am-241 and their size distributions are determined by varying the applied voltage over 2 min. The transient mode measurement, on the other hand, fixes the voltages for the two sections at peaks near 10 and 100 nm in order to monitor the transient behavior of the exhaust nanoparticles. The measurement principles and design of the dual-type DMA are detailed and the results for time response experiments are presented using model nanoparticles charged by a corona charger. The transient concentrations of the nuclei mode and the accumulation mode particles from a diesel engine were shown to be detected by this method, when Am-241 was used for charging the particles.

DOI： 10.1007/s11051-005-3476-y

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

An analyzing technique of the ab initio molecular dynamics simulation is proposed with the use of short-time Fourier transform (ST-FT). The ST-FT analysis demonstrates the dynamical change of the vibrational states in the simulated system. Numerical assessments are preformed for the collision reaction of the ammonia cluster ion NH4+(NH3)(2) with the ammonia monomer NH3. Spectrogram obtained by the ST-FT method, which corresponds to the time evolution of vibrational power spectra, clarifies the relationship between the vibrational states and the reaction channels such as nonreactive collision, substitution, and incorporation.(C) 2004 American Institute of Physics.

DOI： 10.1063/1.1814978

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

A new cluster ion source utilizing corona discharge was studied. Selenium (Se) vapor was ionized by primary nitrogen ions, that were generated by corona discharge. We ionized selenium at the first stage of the cluster ion generation process. The selenium ions in the evaporation chamber can, in principle, promote the cluster growth. We observed cluster ions, Se-n(+) (n = 2 - 4) at 150-280 degreesC, with a pressures range of 240-430 Torr in the corona discharge chamber. The cluster intensities were found to be maximum at a pressure of 300-370 Torr. It was also found that the cluster intensities slowly increased with the temperature. Based on these results, we discuss the cluster ion formation processes. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1702117

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Collisional dynamics of size- and translational-energy-selected protonated water clusters H+(H2O)(n) (n = 2-11) in single collisions with D2O were investigated using guided-ion beam tandem mass spectrometry. The dominant reaction channel for the collision involves the incorporation of D2O into H+(H2O)(n) at low collision energy, whereas at high collision energy, the dissociation of H+(H2O)(n) is predominant. The measured total reaction cross section of H+(H2O)(n) with D2O is found to depend strongly on the cluster size; the cross section drastically increases as the cluster size increases from n = 4 to 5, 6 to 7, and 8 to 9 and has local minima at n = 6 and 8 at collision energies of 0.05 and 0.10 eV, respectively. The size dependence of the total cross section is discussed herein in terms of a comparison with the collision cross section obtained from ab initio calculations.

DOI： 10.1021/jp034129h

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The cross-sections for incorporation of D2O into size- and energy-selected water cluster ions H+(H2O)(n) (n = 2-9) were experimentally measured under single-collision conditions using guided-ion beam tandem mass spectrometry. After estimation of the collision cross-section, the reaction probability for incorporation of D2O into H+(H2O)(n) was investigated as a function of the collision energy. The reaction probability for incorporation was found to be equal to unity at low collision energy by using the experimental data and theoretical curve derived from our model related to the recoil energy of the incident molecule. We examined, by calculation, the temperature dependence of the probability of the incorporation of H2O into neutral water clusters (H2O)(n). (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0301-0104(03)00362-8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Reaction cross sections for the reactions of protonated water clusters, H+(H2O)(n) (n = 1-6) with dirnethylsulfoxide (DMSO) were measured at the collision energy of 0.1 eV. The cross section at n = 2, which was found to be twice as large as that at n = 4, showed a possibility of direct proton transfer process. The proton is likely to transfer directly from H+(H2O)(2) to DMSO without forming an intermediate complex because of the larger proton affinity of DMSO than that of water dimer. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0009-2614(03)01095-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Collisional reactions of size- and energy-selected unprotonated water clusters (H2O)(n)(+) (n = 2 and 3) in a single-collision with D2O were investigated at very low collision energy ranging from 0.05 to 2.0 eV using guided-ion beam tandem mass spectrometry. First, in the unimolecular and collision-induced dissociations of (H2O)(2)(+) and (H2O)(3)(+), only the H2O+ fragment, but not the H3O+ fragment, was observed. These results suggest that the structure of (H2O)(2+) is primarily hemibonded '(H2O...OH2)' rather than proton-transferred '(H3O+...OH)'. Second, the measured incorporation cross-section of (H2O)(2)(+) Was found to be smaller than that of H+(H2O)(2). From the dipole moment obtained by ab initio calculation. we found that the small values of the incorporation cross-section for (H2O)(2)(+) were caused by the small value, 0.0 debye, of the dipole moment of the cluster. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0009-2614(03)01085-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The reactions of size-selected protonated water clusters, H+(H2O)(n) (n = 2-6), with an acetone molecule were studied in a guided ion beam (GIB) apparatus. The collision energy dependence of the reaction cross-sections was investigated over the range of 0.05-2.0 eV in the center-of-mass frame. Water cluster beams with very narrow kinetic energy spreads, 0.02-0.04 eV, were generated to allow accurate measurement of the reaction cross-sections. We observed reaction products of incorporation and dissociation: the incorporation products are cluster ions having acetone whereas the dissociation products are protonated water clusters resulting from the evaporation of water molecule(s) from the parent cluster ions. Our results demonstrate that the incorporation process is dominant at low collision energies and that the proportion of the dissociation process increases as the collision energy increases. The incorporation cross-section at n = 5 is found to be the largest among the cluster sizes examined at the collision energy as low as 0.1 eV, which may be due to the water molecule in the second shell of the cluster. We also find that when the collision energy is larger than 0.5 eV, the dissociation cross-section has a maximum at n = 5, which is also probably due to the water molecule in the second shell of the cluster, and a minimum at n = 3, which may occur because the cluster ion core of the trimer, H3O+, has one H-site that is not occupied by water molecules. (Int J Mass Spectrom 220 (2002) 375-383) (C) 2002 Elsevier Science B.V. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Ab initio molecular dynamic (MD) simulations were performed for investigating collision reaction between NH4+(NH3)(2) trimer and ND3 monomer. Collision cross-section with the use of three criteria was obtained for the collision energy of 0.1-1.0 eV. The MD simulation showed that the reaction followed by the collision is closely connected with the degree of contact in the first collision. (C) 2002 Elsevier Science B.V. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The collisions of size- and energy-selected H+(H2O)(n) (n = 2-11) with D2O have been investigated using guided-ion beam mass spectrometry. The H/D exchange reaction was observed by incorporation of D2O into H+ (H2O)(n). The measured rate constants of this reaction are found to depend strongly on the cluster size- the rate constants drastically decrease up to n = 6, and then level off for 6 less than or equal to n less than or equal to 11. This size dependence is discussed in terms of the structure of protonated water clusters: the core H3O and H5O2+ ions, so-called Eigen and Zundel cations respectively, are completely surrounded by the first water layer and cause the rate constants for 6 less than or equal to n less than or equal to 11 essentially insensitive to n. (C) 2002 Elsevier Science B.V. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

We describe the design and performance of a spectrometer that simultaneously measures the size-dependent concentration and chemical composition of particles ranging from 5 to 40 nm. The spectrometer consists of a differential mobility analyzer for size analysis and an inductively coupled plasma mass spectrometer for composition analysis. For a particle size of 30 nm, the lower detection limit of the spectrometer for particle concentration is about 1 x 10(5) particles cm(-3). (C) 2002 Elsevier Science Ltd. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG  

A mixture of SF6 ( 4% molar fraction) and inert Ar gas was continuously fed into a plane-symmetric guided Laval nozzle, The clustering of SF6 was observed using an FT-IR spectrometer in the nozzle flow (optical pathlength: 10 mm). The density and vibrational temperature of the SF6 monomers were experimentally determined from the absorption peaks of the monomers. We theoretically calculated the density of the SF6 monomers as a function of distance from the throat of the nozzle using a cluster formation model based on the RRK (Rice-Ramsper-Kassel) theory to represent the dynamics of dissociation of the vibrationally excited clusters. We found that the model adequately simulated the decrease in SF6 monomers and 10 collisions of the vibrationally excited SF6 clusters with Ar atoms were necessary for the stabilization of the clusters under our experimental conditions.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

We have developed a differential mobility analyzer (DMA) based on the DMA devised by Seto et al. (1997) and a Faraday cup electrometer for measurement of nanometer-sized particles at a few hundred Pa and examined the operating characteristics of the DMA using the tandem DMA technique. The tandem DMA calibration establishes that the DMA successfully classifies particles in the 200-930 Pa pressure range. It was also found that the transfer function of the DMA follows the triangular transfer function and the resolution of the DMA is close to that given for an ideal case. As a standard of a minimum pressure that may be probed with the present DMA system, 400 Pa is estimated when the DMA operates with a 3 nl min(-1) sheath flow and a 1 nl min(-1) aerosol flow rate. (C) 2000 Elsevier Science Ltd. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Stable geometries and electronic structures of ammonia cluster ions NH4+ (NH3)(n-1) (n = 1-17) are investigated by the ab initio theory in order to clarify the origin of the observed magic number. Since the ammonium ion NH4+ brings about a large attraction to ammonia monomers, the stable geometries of NH4+(NH3)(n-1) (n = 1-17) have shell structures around the ion. The calculated binding energy, which well reproduces the experimental ones, decreases monotonically as the cluster size increases. Gibbs free energies are also estimated with the use of the calculated electronic and vibrational energies. The Gibbs free energy curve with respect to the cluster size gives a minimum at n = 5 in comparatively wide temperature and pressure region, which corresponds to the experimental magic number. The minimum is found to be due to two competitive factors; that is, the nonlinear aspect of the binding energy and the linear instability of the translational entropy as the cluster size increases. (C) 2000 Elsevier Science B.V. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

We theoretically investigated collision cross sections due to the attractive forces between NH4+(NH3)(n-1) (n=2-8) and ND3. We found that the dependence of the collision cross sections on collision energy and cluster size are comparable to those of measured fusion cross sections. The kinetic magic number, n=5, is related to the structure of the pentamer. Namely, the center ion in the pentamer is surrounded by first-shell ammonia molecules. (C) 2000 American Institute of Physics. [S0021-9606(00)00917-X].

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER VERLAG  

SF6 clustering (3%-6% in molar fraction) by homogeneous nucleation in argon was experimentally studied in a steady-state-flow supersonic Laval nozzle. The onset of clustering was detected by FT-IR spectroscopy. Measurements of the static pressure in the nozzle, together with the equations of isentropic flow, yielded the relation between the pressure of SF6, P-c, and the temperature, T-c, at the observed onset of clustering in the range 60 K < T-c < 110 K and 0.1 Torr < P-c < 2.0 Torr. We found that there was no influence of the argon carrier gas pressure, which ranged from 1.9 to 21 Torr at the onset points, on the onset of condensation. In addition, the logarithmic value of the supersaturation ratio was found to linearly depend on T-c(-3/2) at the onset as deduced by Wegener and Wu from the classical theory of homogeneous nucleation [Adv. Colloid Interface Sci. 7, 325 (1977)]. Our results indicate that supersonic expansion in the nozzle did not form heterogeneous clusters consisting of SF6 and Ar but single-component clusters of SF6 in a mixture of SF6 and Ar under the experimental conditions studied herein. We obtained an onset curve (pressure versus temperature) for the SF6 homogeneous clustering, which indicated the boundary for diminishing of the the SF6 monomers in the supersonic Laval nozzle.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

A recently reported intermolecular potential for SF6, featuring exchange, dispersion, and electrostatic terms, is used to determine minimum energy structures of homogeneous SF6 clusters up to the decamer. By adding appropriate interaction terms, also structures of mixed (SF6)a-Ar-n clusters are calculated. A second order line shift formalism, treating the anharmonic intramolecular force field and the intermolecular potential as a perturbation, is employed to calculate the corresponding IR-spectra in the region of the nu(3) vibrational mode of the monomer (at 917.968 cm(-1)). The leading interaction mechanism responsible for the line shifts is confirmed to be the resonant dipole-dipole coupling. The theoretical spectra fairly describe both size-selected spectra for clusters up to the tetramer and recently measured FT-IR spectra in a continuous supersonic Laval nozzle flow.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Science Ltd  

The collision induced reaction of ammonia cluster ions with ND3 molecule was investigated at the collision energies ranging from 0.02 to 1.5 eV in the center-of-mass frame. In the collision of NH4 +(NH3)n-1 with ND3, the two types of cluster ion products, dissociation product and incorporation product, were observed. By measuring the mass spectra of product cluster ions, the reaction rate of incorporation and dissociation for the size-selected ammonia cluster ions was determined.

DOI： 10.1016/S0021-8502(99)80030-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER VERLAG  

Condensation, by homogeneous nucleation, of UF6 carried in a mixture of argon and methane was studied experimentally in a continuously operating supersonic Laval nozzle. The onset of condensation was detected by Rayleigh light scattering. Measurements of static pressure in the nozzle, together with the equations of isentropic flow, permitted the determination of the relation between the pressure of UF6, P-k, and the temperature, T-c, at the observed onset of condensation. The experiments addressed conditions of condensation onset in the range 80 < T-c < 160 K and 0.1 P-k < 3.0 Torr. We found that there was no influence of the pressure of the carrier gas argon, which ranged from 3.5 to 68 Torr at onset points, on the onset of condensation. The dependence of the supersaturation ratio on temperature at the onset could be expressed by a straight line as deduced by P.P. Wegener and B.J.C. Wu from the classical theory of homogeneous nucleation [Adv. Colloid Interface Sci. 7, 325 (1977)]. These results indicate that supersonic expansion in the nozzle formed single-component droplets of UF6 in a mixture of UF6, CH4, and Ar under the experimental conditions studied herein.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

A method based on laser light scattering is presented for the observation of the condensation of working molecules in a steady-state-flow supersonic Laval nozzle operating in a closed loop. The distribution of scattered light from droplets formed by condensation along the flow direction is measured from photographs to determine the point of condensation onset. The temperature and density at the onset point are obtained from the values of static pressure based on the equations of isentropic flow.

DOI： 10.1080/18811248.1998.9733836

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

DOI： 10.1016/S0021-8502(98)00099-8

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記述言語：英語   出版者・発行元：TAYLOR & FRANCIS LTD  

DOI： 10.1080/18811248.1997.9733794

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

The Fourier transform infrared spectra of UF6 clusters seeded in Ar were measured in a continuous supersonic Laval nozzle flow at various pressures. The spectra of the clusters showed completely different features when the total pressure P(total) was changed from 3.0 to 6.0 Torr at a fixed male fraction of UF6, X(UF6) = 0.08. From measurements of the temperature and UF6 monomer density in the nozzle flow, it was found that: the clusters grew in a supercooled state, i.e., at a supersaturation ratio S much greater than 1, when P(total) = 3.0 Torr. In contrast, UF6 clusters grew in a near-equilibrium state, i.e., at S approximate to 1, when P(total) = 6.0 Torr. A comparison between the measured and calculated spectra revealed that the distribution of the potential energy of the cluster configurations was similar to an inverted population at P(total) = 3.0 Torr, and similar to the Boltzmann distribution at P(total) = 6.0 Torr. The fact that the distribution of the potential energy of the cluster configurations was similar to an inverted population in the supercooled state at P(total) = 3.0 Torr was explained qualitatively on the basis of the RRK theory. The spectra measured at X(UF6) = 0.04 support our explanation. (C) 1997 American Institute of Physics.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The FT-IR spectra of clusters of UF6 seeded in argon were measured in a continuous supersonic Laval nozzle Row. We observed absorption peaks of UF6 clusters on both the red- and the blue-shifted sides of the monomer peak (around 627 cm(-1)) at a temperature below 130 K. We assigned these peaks using calculated results on the frequency shifts and transition strength of the IR spectra of UF6 clusters. Clusters as large as 10 in size were found to be for med under our experimental conditions. Vibrational predissociation of UF6 clusters was observed after a single shot from a Raman laser tuned to a vibrational mode of the UF6 clusters (614.8 cm(-1)) in the Laval nozzle. We monitored the concentration of UF6 monomers in the ground state with a diode laser spectrometer, and qualitatively interpreted the time-scale of the predissociation of the UF6 clusters and the recombination of UF6 monomers subsequent to the predissociation in the nozzle. After the UF6 clusters had dissociated in less than 1 ns, the excited monomers formed by the dissociation were deactivated with a time constant of about 0.3 mu s via vibrational relaxation induced by collisions with carrier gas (argon) atoms. The recombination of UF6 monomers produced by the vibrational predissociation competed with vibrational relaxation. The time constant of the recombination (about 6 mu s) was found to be much larger than that of the relaxation. (C) 1997 Elsevier Science B.V.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

DOI： 10.1080/18811248.1997.9733683

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

DOI： 10.1016/S0021-8502(97)85245-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

This article describes the design and performance of a pulsed valve developed as a gas source for a 500-nm-long supersonic Laval nozzle with a 3-mm-wide throat. The valve consists of a plate cam and a valve seat equipped with O-rings on both the upper and lower faces. The duration of quasi-steady-state expansion is measured to be 12 ms at the nozzle throat when the pulsed valve is filled with Ar gas at 100 Torr. (C) 1996 American Institute of Physics.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER VERLAG  

The time-dependent change in the concentration of UF6 monomers populated in the ground state was monitored in a supersonic Laval nozzle how with an infrared diode-laser spectrometer in which the frequency of the laser beam was fixed at the v = 1 <-- 0 transition (627.7 cm(-1)) of the nu(3) vibrational mode of the (UF6)-U-238 monomer. The concentration of UF6 monomers in the ground state increased immediately after a single shot from a Raman laser tuned to a vibrational mode of UF6 clusters (614.8 cm(-1)) was applied to the gas in the nozzle. Subsequently, this concentration leveled off and slowly returned to the previous level. These results indicate that the population of UF6 monomers in the ground state increased as a result of the predissociation of UF6 clusters vibrationally excited with Raman laser radiation. It is demonstrated that one can utilize this procedure for vibrational predissociation of UF6 clusters as a technique to increase the concentration of UF6 monomers in an irradiation zone for molecular laser isotope separation of uranium.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER VERLAG  

A MultiPhoton-Ionization Time-Of-Flight Mass Spectrometry (MPI/TOFMS) apparatus was developed for real-time measurement of the uranium isotopic ratio in nascent UF5 formed by the 266 nm photolysis of effusive UF6 (< 300 K, approximate to 1.3 x 10(-4) Pa). The UF5 was selectively and efficiently multiphoton ionized by 532 nm radiation at appreciably low fluences (< 10 J/cm(2)). The main ions observed, U+ and U2+, were subsequently analyzed with a TOFMS with mass resolution of 1190 to separate U-235(n+) and U-238(n+) completely. The isotopic ratio measurements showed good precision resulting from the excellent agreement which was observed between the isotopic ratios in UF5 products and those in a parent UF6 sample. These results suggested that the MPI/TOFMS method can be applied to the real-time analysis of separation factors in the molecular laser isotope separation of uranium by ionization of UF5 following the infrared photodissociation of UF6.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The clustering of UF6 seeded in Ar was observed in a continuous supersonic Laval nozzle flow. The onset conditions for UF6 clustering were investigated by measuring the FTIR spectra of UF6 monomer and clusters in the nozzle. The onset conditions for the clustering, temperature, density of UF6 (or partial pressure), and cooling rate, were determined as {130 K, 0.009 mol m(-3) (10 Pa), 0.6 x 10(6) K s(-1)} and {155 K, 0.06 mol m(-3) (80 Pa), 1.5 x 10(6) K s(-1)}. The onset temperature determined here was higher by 40-50 K than that determined by a light-scattering method. The frequency shift of the main peak of the UF6 clusters from the monomer peak was about -17 cm(-1), which was smaller than the shift of the crystalline UF6 by about 11 cm(-1). The increase in temperature caused by the heat of condensation and the change of the spectra of UF6 clusters with the growth after the onset were also observed. It was shown that the clustering rate due to the collision between the monomer and cluster is much higher than that due to the collision between the monomers.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

A Separation factor was measured in isotopically selective infrared multiphoton dissociation (IRMPD) of supercooled UF6 in a supersonic expansion by multiphoton ionization (MPI) and time-of-flight mass spectrometry (TOFMS). A pulsed free-jet nozzle was used to generate a UF6-molecular beam seeded in Ar (similar to 10(-7) Torr in UF6 partial pressure). Two-frequency p-H-2 Raman laser beams around 16 mu m were used for the dissociation of UF6 under collisionless conditions in the molecular beam where the flow velocity for UF6 is about 500 m/s. The U-235/U-238 isotopic ratios in nascent UF5 photoproducts were determined by selective MPI of UF5 at 532 nm followed by TOFMS with a mass resolution as high as 1200. A separation factor of about 2 was observed under the experimental conditions chosen for the demonstration of this method.

DOI： 10.1080/18811248.1995.9731833

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The Hamiltonian of the induction effect (dipole-induced dipole interaction) in the model proposed by Snels and Reuss is corrected. This model was proposed for the calculation of the frequency shift and transition strength of the IR spectra of clusters of highly symmetric molecules such as (SF6)(n), (SiF4)(n) and (SM(4))(n). Disagreement between the observed frequency shifts and the calculated results obtained using this model for (SF6)(3) and (SF6)(4) was found to be caused by the incorrect Hamiltonian of the dipole-induced dipole interaction. The calculated results for (SF6)(3) and (SF6)(4) with the corrected Hamiltonian agree with the observed spectra.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

A spectroscopic method is proposed for the simultaneous determination of both the rotational temperature of UF6 diluted with Ar and the total pressure in a supersonic Laval nozzle expansion. This method utilizes the fact that the relative intensities of the sub-bands of a Q branch depend on the rotational temperature and pressure. The values determined for the rotational temperature were found to agree with the temperature calculated on the assumption of thermal equilibrium under isentropic expansion. The total pressures estimated from the Q branch agree with the ones measured with a capacitance manometer.

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記述言語：英語   出版者・発行元：SPRINGER VERLAG  

Measurements of multiphoton absorption of 16 mu m Raman-laser radiation in supercooled (UF6)-U-238 at 90 K were performed by using a pulsed Laval nozzle with an optical path length of 50 cm. The laser fluence was varied between 50 and 500 mJ/cm(2) for four frequencies in the range from 625 to 629 cm(-1). The energy absorbed by (UF6)-U-238 molecules was investigated as a function of laser frequency or fluence, and highly accurate results were obtained with the use of the nozzle whose optical path length is much greater than that of nozzles used before. The results indicated that the absorption cross section at the peak absorption frequency (627.8cm(-1)) was proportional to the -1/3 power of the fluence.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Antimony/magnesium/oxygen clusters are produced by a gas aggregation source, in which a mixture of antimony and magnesium is vaporized and reacted with N2O introduced in helium carrier gas. The resulting product distribution is detected by a time-of-flight mass spectrometer following ionization with a KrF excimer laser. Four types of cluster products are observed: Sb-x(+), SbxMgyOz+, SbxMgy+, and MgyOz+. The mass spectral intensity distributions display enhanced abundances for Mg2O+, Sb2-4Mg3O+, Sb1-4Mg2O+, Sb4Mg+, Sb5Mg2+, and Sb6Mg2+. The experimental observation of Mg2O+ and Mg3O+ shows that the suboxides of group 2 are stable species, consistent with theoretical predictions. The binding abilities of antimony clusters to magnesium and magnesium oxides are found to be dependent on cluster size. When the number of antimony atoms in the clusters is smaller than 6, SbxMgyOz+ are the main products dominating the mass distribution. On the other hand, when the cluster size of Sb-x is larger than 6, only Sb/Mg alloy clusters are observed. The unusual stabilities of Sb2-4Mg3O+ and Sb1-4Mg2O+ clusters are evidently due to the formation of covalent bonds between Sb and Mg atoms. In Sb4Mg+, Sb5Mg2+, and Sb6Mg2+ alloy clusters, however, the Mg atom donates two electrons to the skeleton of the Sb clusters in order to satisfy Wade's rules. The structures of these stable clusters can be predicted by the polyhedral skeletal electronic pair theory.

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記述言語：英語   出版者・発行元：AMER INST PHYSICS  

This note describes the design and performance of a pulsed valve developed as a gas source for a 500 mm long supersonic Laval nozzle with a 3 mm wide throat. The valve consists of a rotating drum with a slit, which allows an opening duration of approximately 14 ms. The duration of quasi-steady-state expansion is measured to be 10 ms at the nozzle throat when the pulsed valve is filled with 200 Torr of Ar gas.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SOC CHEMICAL ENG JAPAN  

A mathematical model is proposed for multifrequency infrared multiphoton dissociation of polyatomic molecules with implications for laser isotope separation. In this model, the dissociation probability is expressed by the functional form based on the product of power-law terms for individual fluences. The data (on the fluence dependence of reaction volume) in the experiments performed on multiphoton dissociation of UF6 cooled at 90 K with multifrequency 16-mum laser beams are utilized to verify our proposed model. This model can show the fluence conditions for high contrast ratios where the dissociation probability for isotopically selective dissociation overwhelms that for nonselective dissociation.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

A method is presented for the determination of the dissociation yield of UF6 in infrared laser isotope separation of uranium. The fluorescence intensity from vibrationally excited HF molecules in the dissociation with 16 mum infrared radiation is related to that in the dissociation with 266 nm ultraviolet radiation for which the absorption cross section and the quantum yield are known. One can calibrate the dissociation yield of UF6 from the fluorescence intensity in 16 mum irradiation, using the experimental result that the fluorescence signal linearly increases with the pulse energy of the 266 nm beam, and the relation derived theoretically between its energy and the number of dissociated molecules. The authors discuss how the fast thermalization of F atoms in both irradiation cases guarantees such a calibration method in spite of the difference in the translational energy of dissociation fragment F atoms.

DOI： 10.1080/18811248.1994.9735128

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHAPMAN HALL LTD  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN SOC APPLIED PHYSICS  

Using a continuous wave CO2 laser, whiskerizing on the surface of carbon fibers was achieved by the catalytic pyrolysis of allene (C3H4). As a catalyst, iron particles generated by laser-induced thermal decomposition of pentacarbonyliron (Fe(CO)5) or ferrocene ((C5H5)2Fe) were used. The whiskers grown on the surface of the carbon fibers were found to have disordered carbon structures, as determined by Raman spectroscopic measurement.

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記述言語：英語   出版者・発行元：TAYLOR & FRANCIS LTD  

DOI： 10.1080/18811248.1991.9731441

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JOHN WILEY & SONS INC  

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ナノクラスター

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第９章1-5分子レーザー法

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招待

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記述言語：英語   出版者・発行元：AMER INST PHYSICS  

An incorporation of ND3 into protonated ammonia cluster ions NH4+(NH3)(n-1) (n=3-9), together with a dissociation of the cluster ions, was observed in the collision of the cluster with ND3 at collision energies ranging from 0.04 to 1.4 eV in the center-of-mass frame. The branching fractions of the cluster ion species produced in the reactions were obtained as a function of the collision energy. The branching fractions of the incorporation products were successfully explained in terms of the Rice-Ramsperger-Kassel (RRK) theory at collision energies lower than the binding energy of the cluster ion. In addition, the internal energy distributions of the parent cluster ions were determined, and found to be in good agreement with those predicted using the evaporative ensemble model. In incorporations at collision energies lower than the binding energy of the cluster ion, all of the collision energy was transferred to the internal energy of the cluster ions; subsequently, an evaporation of ammonia molecules occurred in an equilibrium process after a complete energy redistribution in the clusters. In contrast, at collision energies higher than the binding energy of the cluster ion, a release of an ammonia molecule from the incorporation products occurred in a nonequilibrium process. The transition from the complex mode to the direct mode in the incorporation was observed at collision energies approximately equal to the binding energy. On the other hand, the collision energy dependence of the cross sections for the dissociation and for a nonreactive collision were estimated by a RRK simulation in which the collision energy transfer was interpreted by using the classical hard-sphere collision model. A relationship between reactivity and reaction modes in the collision of NH4+(NH3)(4) with ND3 is discussed via a comparison of the experimental results with the RRK simulation. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1804179

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招待

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招待

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INVITED

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招待

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展望講演

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記述言語：英語   出版者・発行元：Elsevier Science Ltd  

The collision induced reaction of ammonia cluster ions with ND3 molecule was investigated at the collision energies ranging from 0.02 to 1.5 eV in the center-of-mass frame. In the collision of NH4 +(NH3)n-1 with ND3, the two types of cluster ion products, dissociation product and incorporation product, were observed. By measuring the mass spectra of product cluster ions, the reaction rate of incorporation and dissociation for the size-selected ammonia cluster ions was determined.

DOI： 10.1016/S0021-8502(99)80030-5

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INVITED

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記述言語：英語   出版者・発行元：Springer Verlag  

The time-dependent change in the concentration of UF6 monomers populated in the ground state was monitored in a supersonic Laval nozzle flow with an infrared diode-laser spectrometer in which the frequency of the laser beam was fixed at the v = 1 ← 0 transition (627.7 cm-1) of the V3 vibrational mode of the 238UF6 monomer. The concentration of UF6 monomers in the ground state increased immediately after a single shot from a Raman laser tuned to a vibrational mode of UF6 clusters (614.8 cm-1) was applied to the gas in the nozzle. Subsequently, this concentration leveled off and slowly returned to the previous level. These results indicate that the population of UF6 monomers in the ground state increased as a result of the predissociation of UF6 clusters vibrationally excited with Raman laser radiation. It is demonstrated that one can utilize this procedure for vibrational predissociation of UF6 clusters as a technique to increase the concentration of UF6 monomers in an irradiation zone for molecular laser isotope separation of uranium.

DOI： 10.1007/BF01112839

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記述言語：英語   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

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記述言語：英語   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

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記述言語：英語   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

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開催地：Xi'an  

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開催地：堺  

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開催地：Xi'an  

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開催地：堺  

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開催地：京都  

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開催地：名古屋  

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開催地：東大阪  

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開催地：福岡  

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開催地：Kyoto  

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開催地：Tokyo  

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開催地：Bangkok  

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開催地：つくば  

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開催地：札幌  

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開催地：Ghent  

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開催地：Ghent  

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開催地：Zurich, Switzerland  

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開催地：仙台  

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開催地：つくば  

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開催地：仙台  

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公開番号：特開2000-37940 

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特許番号/登録番号：特許-3294228 

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公開番号：特開2005-214931 

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公開番号：特開2002-190258 

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公開番号：特開2007-315817 

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特許番号/登録番号：特許-2752023 

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公開番号：特開H09-024248 

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公開番号：特開H07-227524 

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