Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Proton transfer from multiply-protonated ubiquitin ions, [M+zH](+z) (z = 6-12), to 1-butylamine was studied in the gas phase. Absolute reaction rate constant for proton transfer was determined from intensities of parent and product ions in the mass spectra. The reaction rate constant increased rapidly with increase of charge states for parent ions. By changing temperature of collision cell in region from 280 to 450 K, temperature dependence of reaction rate constant and branching fractions for proton transfer was measured. Dramatic change was observed for distribution of product ions and reaction rate constant. These results would correlate with conformation change of ubiquitin ions with change of temperature, which originates in self-solvation to protons by hydrophilic residues in polypeptide chains, delocalization of charges with self-solvation, and Coulomb repulsion between charges. (C) 2013 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.chemphys.2013.02.009

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Relaxation process of ammoniated NH4 radicals in the first excited state is studied with a femtosecond pump-probe technique and a time-of-flight mass spectroscopy. Small ammoniated NH4 radicals are produced by an ArF-excimer laser photolysis of ammonia clusters. The decay of the excited state is probed by a resonance-enhanced two-photon ionization method. NH4 radical in the first excited state is found to have a lifetime of an order of 50 ps. The lifetimes of NH4(NH3)(n) decrease from 1.4 ps (n = 1) to 300 fs (n = 4) with increasing the number of solvent molecules. The large reduction of the lifetimes is ascribed to the enhancement of nonradiative decay process as a result of the drastic change in the electronic structure of these clusters with the addition of ammonia molecules. For larger clusters (n greater than or equal to 5), the lifetime becomes almost constant at 120 fs. The observed size dependence of the lifetimes is discussed in relation to the formation of a one-center ion-pair state by the spontaneous ionization of NH4 in ammonia clusters.

DOI： 10.1021/jp030784d

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Electronic spectra of ammoniated ammonium radicals, NH4(NH3)(n), produced through the photolysis of ammonia clusters, are investigated with a laser photodepletion spectroscopy. Vibrationaly resolved bands beginning at energy of 9305 +/- 15 cm(-1) are successfully assigned to NH4NH3. These bands are ascribed to the 2 (2)A -1 (2)A transition derived from the 3p F-2(2)-3s (2)A(1) excitation of NH4. A second group of bands beginning at energy 10073 +/- 15 cm(-1) is assigned to the 1(2)E-1(2)A transition. Electronic spectra of a series of NH4(NH3), (n = 1-8) are also recorded with low resolution in the energy region of 4500-16000 cm(-1). A drastic decrease of the excitation energy from 15062 cm(-1) for NH4 to 5800 cm(-1) for NH4(NH3)(4) is observed, while no appreciable spectral change is found for n greater than or equal to 5. The large spectral change is ascribed to the spontaneous ionization of NH4 in ammonia clusters. Successive binding energies of NH4(NH3)(n) in the excited state are determined from the spectral band positions.

DOI： 10.1021/jp0145457

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For the collision-induced dissociation of small cationic aluminum clusters, the release of Al+ is known to dominate. An exception is Al-8(+), where we find the neutral atom evaporation to be energetically favorable, and to couple strongly with the Al+ release. These experimental results are discussed in the frame of the Clemenger-Nilsson electronic shell model. We find the electronic shell model to offer a consistent interpretation of the energy dependence of the dissociation dynamics of Al-8(+), if the crucial role of collisional deformation is taken into account. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0009-2614(99)00876-3

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Energy-resolved collision-induced dissociation (CID) of Al-n(+) (n = 2 - 11) in collision with argon is presented for the energy ranges from few hundred meV to 10 eV in the center of mass frame. The experiments were carried out with a recently constructed secondary ion tandem mass spectrometer, that is described in detail. The collision energy dependence is measured for the total and the partial dissociation cross sections, and the dissociation thresholds for the individual processes are estimated. The release of Al+ is found to be the dominating channel for n < 8. For n > 8, the cross section for the release of Al+ and Al are comparable. The release of more than one neutral atom from the larger clusters (n > 6) is found to be in good agreement with sequential atom loss. In the case of the smaller clusters, on the other hand, fission is the energetically favorable process. The closed shell cluster, Al-7(+) (20 valence electrons), is found to be exceptionally stable and the adiabatic ionization potential of Al-7 is found to be lower than that of the monomer. The stability of Al-7(+) is further reflected in the dissociation dynamics of the next neighbor, Al-8(+). The high stability of Al-7(+) as well as the dissociation dynamics of Al-8(+) are treated in the simple frame of the electronic shell model. Unlike Al-7(+), Al-3(+) (with 8 valence electrons) shows no sign of increased stability, and the dissociation dynamics seems to be controlled by the spin selection rules, rather than the energetics. In the present work, general trends and the dissociation dynamics of individual clusters are discussed. Qualitative information on the development of the geometric and electronic structure, with increasing cluster size, is deduced and discussed in terms of a transition from a covalent to a metallic character. Finally, this work is compared to earlier theoretical and experimental approaches to Al-n(+) clusters. (C) 1999 American Institute of Physics. [S0021-9606(99)00808- 9].

DOI： 10.1063/1.478320

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A collisional reaction of a sodium cluster ion, Na-n(+)(n=3-9), with a nitrous oxide molecule, N2O, was investigated by using a tandem mass-spectrometer equipped with four octopole ion guides. Two types of ions, NakO+ and Na-P(+) (p<n), were produced by the reaction; NakO+ and Na-p(+) result from oxidation and direct collisional dissociation of the parent cluster ion, Na-n(+), respectively. The absolute total cross section and partial cross sections for the NakO+ (oxidation) and Na-P(+) (direct dissociation) production were measured as a function of the collision energy of a given parent cluster ion, Na-n(+), in the energy range up to 5 eV (center-of-mass frame). The cross sections and their collision-energy dependence show that the oxidation proceeds when electron harpooning from Na-n(+) to N2O occurs and otherwise the direct collisional dissociation proceeds. (C) 1997 American Institute of Physics.

DOI： 10.1063/1.473117

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Reaction dynamics of sodium cluster ions, Na-n(+) (n = 2 - 9), in collision with molecular oxygen, O-2 was investigated by measuring the absolute dissociation cross sections and the branching fractions by using a tandem mass spectrometer equipped with several octapole ion guides. The mass spectrum of the product ions show that the dominant reaction channels are production of oxide ions, NakOi (i = 1,2), and intact ions, Na-p(+) (p < n). With increase in the collision energy, the cross section for the production of the oxide ions decreased, while that for the production of the intact ions increased. The collision-energy dependences of the cross section for the oxide formation reveals that electron harpooning from the molecule to Na-n(+), preludes the oxide-ion formation. On the other hand, the collision-energy dependences of the cross sections for the intact ion formation is explained by a hard-sphere-collision model similar to the collisional dissociation of Na-n(+) by rare-gas impact.

DOI： 10.1007/s004600050161

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Dissociation dynamics of a sodium cluster ion, Na-n(+) (n=2-9 and 11), in collision with a rare gas atom (He or Ne) was investigated by measuring the absolute cross sections for the production of fragmented ions by using a tandem mass-spectrometer equipped with several octapole ion guides. The mass spectra of the fragmented ions show that release of Na and/or Na-2 from Na-n(+) occurs dominantly. The absolute total cross section for the dissociation of Na-n(+) and the absolute partial cross sections for the Na and/or the Na-2 release were determined at different collision energies and cluster sizes. The absolute total dissociation cross sections were calculated by a scheme that f dissociates with leaving Na and Na-2 unimolecularly, On the other hand, collisionally excited Na-n(+) the partial cross sections;for the Na and the Na-2 release were successfully explained by the orbital correlation diagram for the dissociation system; the dissociation channel involving an adiabatic transition was found to be influenced significantly by the collision energy and the cluster size. (C) 1996 American Institute of Physics.

DOI： 10.1063/1.472750

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Vibrational predissociation spectra of NH4+(NH3)(n-1) (n = 6-9) were measured in the wavenumbers of 1045 - 1091 cm(-1) by using a tandem mass spectrometer equipped with a serpentine octopole ion guide and a line-tunable cw CO2 laser. Each spectrum consists of an intense and broad peak and a weak one. The dissociation cross sections were in the order of 10(-17)-10(-18) cm(2). As n increases, the wavenumber of the intense and broad peak red-shifts gradually, and its intensity increases. The Hartree-Fock and the second-order Moller-Plesset calculations were performed to obtain the wavenumbers and the intensities of the optical absorption by these cluster ions with n = 2-8. The comparison of the experimental results with the calculations leads us to conclude that NH4+(NH3)(n-1) forms a shell structure and causes the absorption band associated with the collective v(2) vibration of NH3 to split.

DOI： 10.1021/jp960003r

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A sodium cluster ion, Na-9(+), having a closed electronic shell was allowed to collide with a rare-gas atom (He or Ne), and collisionally fragmented ions were measured by using a tandem mass-spectrometer equipped with several octapole ion guides. The mass spectrum of the product ions show that sodium atom and dimer are released dominantly from the cluster ion, Na-9(+). The dependencies of the absolute cross sections for the Na and the Na-2 release on the collision energy were determined for collision energies up to 3 eV in the center of mass frame. The cross section for the Na-2 release increases much more rapidly than that for the Na release as the collision energy increases, while the cross sections for the Na and the Na-2 release start to rise at almost the same collision energy of 0.75 +/- 0.1 eV. The collision-energy dependencies are explained by orbital correlation diagrams for the Na-8(+) + Na and the Na-7(+) + Na-2 systems on the basis of a model that a spherical jellium of Na-9(+) is deformed by collision of a rare-gas atom. The total absolute cross sections are estimated by a two-step scheme: collisional excitation and dissociation. (C) 1996 American Institute of Physics.

DOI： 10.1063/1.471318

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The collisional reaction of Na-n(+) (2 less than or equal to n less than or equal to 9) with N2O was investigated by using a tandem mass spectrometer equipped with four octopole ion guides. Oxide ions, NakO+, and intact ions, Na-p(+) (p < n), were found to be produced from the reaction of Na-n(+) with N2O. The collision-energy dependence of the absolute cross section for each product channel was measured at collision energies up to 5 eV in the center-of-mass frame. The cross section for the production of NakO+ decreased with increasing collision energy, while that for the production of Na-p(+) increased. This observation is interpreted as that electron harpooning from Na-n(2) to N2O preludes NakO+ formation. The collision-energy dependence of the partial cross section for the production of Na-p(+) is explained by a hard sphere collision model employed in the explanation of the collisional dissociation of Na-n(2) by rare-gas impact.

DOI： 10.1016/0009-2614(96)00233-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Universal Academy Press  

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Collision-induced dissociation (CID) of acrylonitrile (AN: CH2=CHCN) cluster cations and anions, (AN)(n)(+/-) (n = 2-11), with an Ne or Kr atom was investigated in order to elucidate their structures. In the collision of (AN)(n)(-) with a rare gas atom, [(AN)(n)-X](-) (X = HCN, CH2CN) were produced along with (AN)(m)(-) (m less than or equal to n). The size distributions of the product anions show that (AN)(n)(-) is composed of a chemically bonded trimeric core anion solvated with chemically bonded AN trimer units and AN monomers. On the ether hand, in a 1.0-eV collision of (AN)(n)(+) with a Kr atom, (AN)(m)(+) (m less than or equal to n) were produced by evaporation of acrylonitrile molecules.

DOI： 10.1021/j100048a008

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We report the formation of dihalide products from the endothermic gas-phase ion-molecule reaction of Cl- with CH3Br at suprathermal collision energies using both guided ion beam and selected ion flow drift tube (SIFDT) techniques. The cross sections for the Cl- + CH3Br reactions were determined using the guided ion beam apparatus over a center-of-mass collision energy range of 2-15 eV with the ClBr- product displaying a maximum near 7 eV. This result is found to be in good agreement (when convoluted with the appropriate velocity distribution) with the rate constant measured by the SIFDT. ICI- and I-2(-) are also found for the Cl- + CH3I and I- + RI reactions at elevated collision energies (less than or equal to 1.5 eV) in the SIFDT. The rates for halide displacement are found to be insensitive to collision energy. These results indicate that attack on the C-X bond may nor provide an efficient alternative to the S(N)2 mechanism for halide exchange in the asymmetric X(-) + CH3Y systems. This conclusion is supported by nb initio calculations (MP2LANL10Z level) which indicate that ClBr- can be formed by collinear attack at the halogen through a Cl...Br...CH3 intermediate.

DOI： 10.1021/ja00111a023

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Dissociation dynamics of Ar cluster ions, Ar-n(+) (n = 3 - 16), in collision with He and Ne atoms was investigated by measuring the absolute dissociation cross sections and the branching fractions of the product ions at the collision energies of 0.1-10 eV in the center-of-mass frame. The cross sections and the branching fractions were successfully explained in terms of collisional excitation of the parent cluster ion and subsequent dissociation of it; the collisional excitation was treated by a hard sphere collision model with the aid of the molecular dynamics (MD) and the diatomics-in-molecules (DIM) calculations reported previously, and the subsequent dissociation was explained by the Rice-Ramsperger-Kassel (RRK) theory.

DOI： 10.1063/1.468357

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Collision of Ar cluster ions, Ar(n)+ (n = 3-16), with He and Ne atoms was investigated by use of mass spectroscopic techniques. The cross sections for the production of Ar(n')+ (n' < n) were measured as functions of the size of the parent cluster ion and the collision energy (0.1-10 eV in the center-of-mass frame). These results were analyzed in the scheme of hard-sphere spectator collision with RRK theory. It was concluded that the reaction proceeds via collisional excitation of the parent cluster ion and following sequential loss of the constituent Ar atoms.

DOI： 10.1007/BF01437834

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Dissociation of protonated methanol cluster ions, (CH3OHH+ (n = 2-23), in collision with He, Ne, or Kr atoms were studied by means of a tandem mass spectrometer equipped with octapole ion guides. The mass spectra of the product ions show that the dominant process is evaporation of CH3OH molecules from (CH3-OHH+. The absolute cross section for the evaporation was measured as functions of the cluster sizes and the collision energy in the range 0.05-100 eV in the center of mass frame. The branching fractions for the product ions were also determined. It is inferred that the evaporation proceed via the collisional excitation and subsequent unimolecular dissociation.

DOI： 10.1021/j100087a009

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The collision-induced reaction of Ar-n(+) (n=2-23) with Ar-36 was investigated at the collision energies of 0.2 and 2.0 eV. The product ions were Ar-n'(+), and (ArArn'-1+)-Ar-36 (n'<n). The absolute cross sections for the product formation were obtained as a function of the size of the parent cluster ion. The cross section for the formation of Ar-n'(+) (evaporation) increased rapidly with n in the n less than or equal to 9 range, and slowly above it; the cross section at n=23 was approximate to 180 Angstrom(2). On the other hand, the cross section for the (ArArn'-1+)-Ar-36 formation (fusion) started to rise at n=7 and increased slowly as n increases. In order to elucidate the reaction scheme, the molecular dynamics (MD) simulation based on the diatomics-in-molecules (DIM) method was performed. The reaction (evaporation and fusion) cross sections estimated from the simulation reproduced the observed ones within an accuracy of 15% at n=6, 13, and 19 at the collision energy of 0.2 eV. The following reaction scheme based on this simulation was found to explain the experimental results: collisional excitation of the parent cluster ion Ar-n(+) and subsequent unimolecular dissociation (evaporation), and formation of a collision complex (ArArn+)-Ar-36 and subsequent unimolecular dissociation (fusion). In addition, it was confirmed by the MD calculation that the fusion proceeded via perfectly inelastic collision and following evaporation in the 0.2 eV collision of Ar-10(+) with Ar-36.

DOI： 10.1063/1.467055

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DOI： 10.1021/j100370a006

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The reactions of vanadium and cobalt clusters, generated by laser vaporization, with ethylene and acetylene were studied by using a fast flow reactor. In the reaction of small Vn with C2H4, the dehydrogenated products VnC2, VnC2H2 increasing the cluster number, the intensities of those products decrease monotonically, while those of VnC2H4 increase. Similar results were observed in the reaction of Vn with C2H2. On the other hand, only non-dehydrogenated products were observed in the reaction of small Con with C2H4, but for larger clusters (n ? 9) the dehydrogenated products ConC2 and ConC2H2 appeared. The contrast between the reaction of Vn and Con is related to the heats of adsorption and the structure of adsorbed products. ? 1989.

DOI： 10.1016/0009-2614(89)87310-5

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The reactions of small alloy clusters, which are made of Al and some transition metals such as Co and Nb, with H2 were studied using a fast flow reactor. Two factors - electronic and structural - are important for activation of coadsorption of Al atoms. Addition of only one Al atom to Con clusters induced a sudden increase of reactivity even though Aln clusters hardly adsorb H2. Because valence orbitals of Al atom hybridize with upper states of the valence band of the clusters, the Al atom activates the adsorption sites on the clusters. On the contrary, upon adding one Al atom to Nb5-7, extensively reactive clusters, a sudden decrease of reactivity was observed, perhaps because the Al atom gets into their active sites and blocks chemisorption of H2 on the Nbn clusters. © 1989.

DOI： 10.1016/0009-2614(89)85232-7

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The reaction of aluminum clusters, Aln (n=7-24), formed by laser vaporization, with oxygen and ammonia was studied by using a fast flow reactor. It was found that the oxygen reacts strongly with aluminum clusters to form chemisorbed products while ammonia is adsorbed weakly with Aln in a physisorbed form. In the reaction with oxygen under multiple collision conditions, a mixed cluster, Al9O7, was found to be formed selectively. ? 1988.

DOI： 10.1016/0009-2614(88)85012-7

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DOI： 10.1063/1.452695

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DOI： 10.1063/1.451213

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Proton transfer from multiply-protonated ubiquitin ions, [M+zH](+z) (z = 6-12), to 1-butylamine was studied in the gas phase. Absolute reaction rate constant for proton transfer was determined from intensities of parent and product ions in the mass spectra. The reaction rate constant increased rapidly with increase of charge states for parent ions. By changing temperature of collision cell in region from 280 to 450 K, temperature dependence of reaction rate constant and branching fractions for proton transfer was measured. Dramatic change was observed for distribution of product ions and reaction rate constant. These results would correlate with conformation change of ubiquitin ions with change of temperature, which originates in self-solvation to protons by hydrophilic residues in polypeptide chains, delocalization of charges with self-solvation, and Coulomb repulsion between charges. (C) 2013 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.chemphys.2013.02.009

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Language：Japanese   Publisher：横浜市立大学学術研究会  

DOI： 10.15015/00000270

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Photo-induced reactions and metastable decompositions of cluster ions containing glycine, tryptophan, tryptophanylglicine and [Fe(III)- protoporphyrin](+) (hemin(+)) ions solvated with water molecules are studied with electrospray ionization (ESI). The ESI ion source is improved to produce hydrated biomolecular cluster ions. Metastable decompositions of the hydrated clusters following primary mass selection are measured to determine the incremental solvent binding energies for the clusters by using evaporative ensemble model. From these experimental findings, stability of the cluster ions is discussed in terms of delocalization of ionic charges. We also measure the photodissociation yields of mass-selected water clusters containing hemin(+) ions at 355 and 532 nm. The mass spectra of photofragments show the beta-cleavage of carboxymethyl groups in addition to the evaporation of solvent molecules.

DOI： 10.1140/epjd/e2005-00166-9

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Relaxation process of ammoniated NH4 radicals in the first excited state is studied with a femtosecond pump-probe technique and a time-of-flight mass spectroscopy. Small ammoniated NH4 radicals are produced by an ArF-excimer laser photolysis of ammonia clusters. The decay of the excited state is probed by a resonance-enhanced two-photon ionization method. NH4 radical in the first excited state is found to have a lifetime of an order of 50 ps. The lifetimes of NH4(NH3)(n) decrease from 1.4 ps (n = 1) to 300 fs (n = 4) with increasing the number of solvent molecules. The large reduction of the lifetimes is ascribed to the enhancement of nonradiative decay process as a result of the drastic change in the electronic structure of these clusters with the addition of ammonia molecules. For larger clusters (n greater than or equal to 5), the lifetime becomes almost constant at 120 fs. The observed size dependence of the lifetimes is discussed in relation to the formation of a one-center ion-pair state by the spontaneous ionization of NH4 in ammonia clusters.

DOI： 10.1021/jp030784d

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Photo-induced reaction of [Fe(III)-protoporphyrin](+) (hemin(+)) ions solvated with dimethylsulfoxide (DMSO) is investigated by using a tandem mass spectrometer with electrospray ionization. We measure the photodissociation yields of mass-selected hemin(+()DMSO)(n) clusters for n = 0-3. The mass spectra of the fragment ions show the beta-cleavage of carboxymethyl groups in addition to the evaporation of solvent molecules. Yield of the beta-cleavage reaction is found to depend strongly on the excitation energv and the number of solvent molecules. We also examine photo-induced reactions of multiply-charged cytochrome c ions, (M + nH)(n+) (n = 9-17). Photoionization is found to be the dominant process for the lower charged states (n = 9-12) and its yield decreases rapidly with increasing the charge. The photoionization is ascribed to the emission of electron by multiphoton excitation of heme under the influence of Coulomb attractive potential arising from the charges in the polypeptide chain. Model calculations of the Coulomb potential suggest that the structure of the polypeptide chain is completely elongated.

DOI： 10.1140/epjd/e2003-00168-7

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Photo-induced reaction of [Fe(III)-protoporphyrin](+) (hemin(+)) ions solvated with dimethylsulfoxide (DMSO) is investigated by using a tandem mass spectrometer with electrospray ionization. We measure the photodissociation yields of mass-selected hemin(+)(DMSO)(n) clusters for n = 0-3 in the energy region of 15 800-28 200 cm(-1). The mass spectra of the fragment ions show the beta-cleavage of carboxymethyl groups in addition to the evaporation of solvent molecules. Yield of the beta-cleavage reaction is found to depend strongly on the excitation energy and the number of solvent molecules. We also examine the metastable decomposition of the clusters following primary mass selection and determine the incremental solvent binding energies and internal energies for the clusters using evaporative ensemble model. From these results, we investigate the reaction mechanism of beta-cleavage of hemin(+) ion.

DOI： 10.1140/epjd/e2002-00153-8

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Electronic spectra of ammoniated ammonium radicals, NH4(NH3)(n), produced through the photolysis of ammonia clusters, are investigated with a laser photodepletion spectroscopy. Vibrationaly resolved bands beginning at energy of 9305 +/- 15 cm(-1) are successfully assigned to NH4NH3. These bands are ascribed to the 2 (2)A -1 (2)A transition derived from the 3p F-2(2)-3s (2)A(1) excitation of NH4. A second group of bands beginning at energy 10073 +/- 15 cm(-1) is assigned to the 1(2)E-1(2)A transition. Electronic spectra of a series of NH4(NH3), (n = 1-8) are also recorded with low resolution in the energy region of 4500-16000 cm(-1). A drastic decrease of the excitation energy from 15062 cm(-1) for NH4 to 5800 cm(-1) for NH4(NH3)(4) is observed, while no appreciable spectral change is found for n greater than or equal to 5. The large spectral change is ascribed to the spontaneous ionization of NH4 in ammonia clusters. Successive binding energies of NH4(NH3)(n) in the excited state are determined from the spectral band positions.

DOI： 10.1021/jp0145457

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Electronic absorption spectra of NH4(NH3)(n) (n = 1 - 6) were measured in the energy region of 4500-14000 cm(-1). The spectra were assigned to the transition derived from a 3p(2)F(2) - 3s(2)A(1) Rydberg-Rydberg transition of NH4. A drastic decrease of excitation energy from the transition of NH4 (15 062 cm(-1)) down to 5800 cm(-1) for NH4(NH3)(4) cluster was observed, while there was no clear difference for n = 4, 5; and 6. Successive binding energies of NH4(NH3)(n) in the 3p-type state determined from the spectra were found to decrease monotonically with increasing n, in a similar manner to those of a positive ion, NH4+. The drastic spectral change was ascribed to spontaneous ionization of NH4 in ammonia clusters.

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For the collision-induced dissociation of small cationic aluminum clusters, the release of Al+ is known to dominate. An exception is Al-8(+), where we find the neutral atom evaporation to be energetically favorable, and to couple strongly with the Al+ release. These experimental results are discussed in the frame of the Clemenger-Nilsson electronic shell model. We find the electronic shell model to offer a consistent interpretation of the energy dependence of the dissociation dynamics of Al-8(+), if the crucial role of collisional deformation is taken into account. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0009-2614(99)00876-3

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Energy-resolved collision-induced dissociation (CID) of Al-n(+) (n = 2 - 11) in collision with argon is presented for the energy ranges from few hundred meV to 10 eV in the center of mass frame. The experiments were carried out with a recently constructed secondary ion tandem mass spectrometer, that is described in detail. The collision energy dependence is measured for the total and the partial dissociation cross sections, and the dissociation thresholds for the individual processes are estimated. The release of Al+ is found to be the dominating channel for n < 8. For n > 8, the cross section for the release of Al+ and Al are comparable. The release of more than one neutral atom from the larger clusters (n > 6) is found to be in good agreement with sequential atom loss. In the case of the smaller clusters, on the other hand, fission is the energetically favorable process. The closed shell cluster, Al-7(+) (20 valence electrons), is found to be exceptionally stable and the adiabatic ionization potential of Al-7 is found to be lower than that of the monomer. The stability of Al-7(+) is further reflected in the dissociation dynamics of the next neighbor, Al-8(+). The high stability of Al-7(+) as well as the dissociation dynamics of Al-8(+) are treated in the simple frame of the electronic shell model. Unlike Al-7(+), Al-3(+) (with 8 valence electrons) shows no sign of increased stability, and the dissociation dynamics seems to be controlled by the spin selection rules, rather than the energetics. In the present work, general trends and the dissociation dynamics of individual clusters are discussed. Qualitative information on the development of the geometric and electronic structure, with increasing cluster size, is deduced and discussed in terms of a transition from a covalent to a metallic character. Finally, this work is compared to earlier theoretical and experimental approaches to Al-n(+) clusters. (C) 1999 American Institute of Physics. [S0021-9606(99)00808- 9].

DOI： 10.1063/1.478320

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Dissociation dynamics of a size-selected sodium cluster ion, Na-9(+), in collision with a series of rare-gas atoms, He, Ne, Ar, Kr and Xe, was investigated by measuring the absolute cross sections by use of a tandem mass-spectrometer, The dominant processes for the dissociation are Na and Na-2 release from the parent cluster ion. Total cross sections for the dissociation except for the Xe collision is explained in a scheme of classical collision. In the Xe collision, it was found that the cross sections observed were smaller than the cross sections predicted by the classical collision scheme, probably because of long range interaction between the cluster ion and Xe atom. On the other hand, the branching fractions for the Na and the Na-2 release are predicted well by the orbital correlation diagrams for the dissociation systems.

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Language：Japanese   Publisher：物性研究刊行会  

この論文は国立情報学研究所の電子図書館事業により電子化されました。

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A collisional reaction of a sodium cluster ion, Na-n(+)(n=3-9), with a nitrous oxide molecule, N2O, was investigated by using a tandem mass-spectrometer equipped with four octopole ion guides. Two types of ions, NakO+ and Na-P(+) (p<n), were produced by the reaction; NakO+ and Na-p(+) result from oxidation and direct collisional dissociation of the parent cluster ion, Na-n(+), respectively. The absolute total cross section and partial cross sections for the NakO+ (oxidation) and Na-P(+) (direct dissociation) production were measured as a function of the collision energy of a given parent cluster ion, Na-n(+), in the energy range up to 5 eV (center-of-mass frame). The cross sections and their collision-energy dependence show that the oxidation proceeds when electron harpooning from Na-n(+) to N2O occurs and otherwise the direct collisional dissociation proceeds. (C) 1997 American Institute of Physics.

DOI： 10.1063/1.473117

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Reaction dynamics of sodium cluster ions, Na-n(+) (n = 2 - 9), in collision with molecular oxygen, O-2 was investigated by measuring the absolute dissociation cross sections and the branching fractions by using a tandem mass spectrometer equipped with several octapole ion guides. The mass spectrum of the product ions show that the dominant reaction channels are production of oxide ions, NakOi (i = 1,2), and intact ions, Na-p(+) (p < n). With increase in the collision energy, the cross section for the production of the oxide ions decreased, while that for the production of the intact ions increased. The collision-energy dependences of the cross section for the oxide formation reveals that electron harpooning from the molecule to Na-n(+), preludes the oxide-ion formation. On the other hand, the collision-energy dependences of the cross sections for the intact ion formation is explained by a hard-sphere-collision model similar to the collisional dissociation of Na-n(+) by rare-gas impact.

DOI： 10.1007/s004600050161

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Dissociation dynamics of a sodium cluster ion, Na-n(+) (n=2-9 and 11), in collision with a rare gas atom (He or Ne) was investigated by measuring the absolute cross sections for the production of fragmented ions by using a tandem mass-spectrometer equipped with several octapole ion guides. The mass spectra of the fragmented ions show that release of Na and/or Na-2 from Na-n(+) occurs dominantly. The absolute total cross section for the dissociation of Na-n(+) and the absolute partial cross sections for the Na and/or the Na-2 release were determined at different collision energies and cluster sizes. The absolute total dissociation cross sections were calculated by a scheme that f dissociates with leaving Na and Na-2 unimolecularly, On the other hand, collisionally excited Na-n(+) the partial cross sections;for the Na and the Na-2 release were successfully explained by the orbital correlation diagram for the dissociation system; the dissociation channel involving an adiabatic transition was found to be influenced significantly by the collision energy and the cluster size. (C) 1996 American Institute of Physics.

DOI： 10.1063/1.472750

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Vibrational predissociation spectra of NH4+(NH3)(n-1) (n = 6-9) were measured in the wavenumbers of 1045 - 1091 cm(-1) by using a tandem mass spectrometer equipped with a serpentine octopole ion guide and a line-tunable cw CO2 laser. Each spectrum consists of an intense and broad peak and a weak one. The dissociation cross sections were in the order of 10(-17)-10(-18) cm(2). As n increases, the wavenumber of the intense and broad peak red-shifts gradually, and its intensity increases. The Hartree-Fock and the second-order Moller-Plesset calculations were performed to obtain the wavenumbers and the intensities of the optical absorption by these cluster ions with n = 2-8. The comparison of the experimental results with the calculations leads us to conclude that NH4+(NH3)(n-1) forms a shell structure and causes the absorption band associated with the collective v(2) vibration of NH3 to split.

DOI： 10.1021/jp960003r

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Language：English   Publisher：Elsevier  

The collisional reaction of Na+ n ( 2 ≤ n ≤ 9) with N2O was investigated by using a tandem mass spectrometer equipped with four octopole ion guides. Oxide ions, NakO+, and intact ions, Na+ p (p &lt
n), were found to be produced from the reaction of Na+ n with N2O. The collision-energy dependence of the absolute cross section for each product channel was measured at collision energies up to 5 eV in the center-of-mass frame. The cross section for the production of NakO+ decreased with increasing collision energy, while that for the production of Na+ p increased. This observation is interpreted as that electron harpooning from Na2 n to NakO+ preludes NakO+ formation. The collision-energy dependence of the partial cross section for the production of Na+ p is explained by a hard sphere collision model employed in the explanation of the collisional dissociation of Na2 n by rare-gas impact.

DOI： 10.1016/0009-2614(96)00233-3

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The collisional reaction of Na-n(+) (2 less than or equal to n less than or equal to 9) with N2O was investigated by using a tandem mass spectrometer equipped with four octopole ion guides. Oxide ions, NakO+, and intact ions, Na-p(+) (p < n), were found to be produced from the reaction of Na-n(+) with N2O. The collision-energy dependence of the absolute cross section for each product channel was measured at collision energies up to 5 eV in the center-of-mass frame. The cross section for the production of NakO+ decreased with increasing collision energy, while that for the production of Na-p(+) increased. This observation is interpreted as that electron harpooning from Na-n(2) to N2O preludes NakO+ formation. The collision-energy dependence of the partial cross section for the production of Na-p(+) is explained by a hard sphere collision model employed in the explanation of the collisional dissociation of Na-n(2) by rare-gas impact.

DOI： 10.1016/0009-2614(96)00233-3

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A sodium cluster ion, Na-9(+), having a closed electronic shell was allowed to collide with a rare-gas atom (He or Ne), and collisionally fragmented ions were measured by using a tandem mass-spectrometer equipped with several octapole ion guides. The mass spectrum of the product ions show that sodium atom and dimer are released dominantly from the cluster ion, Na-9(+). The dependencies of the absolute cross sections for the Na and the Na-2 release on the collision energy were determined for collision energies up to 3 eV in the center of mass frame. The cross section for the Na-2 release increases much more rapidly than that for the Na release as the collision energy increases, while the cross sections for the Na and the Na-2 release start to rise at almost the same collision energy of 0.75 +/- 0.1 eV. The collision-energy dependencies are explained by orbital correlation diagrams for the Na-8(+) + Na and the Na-7(+) + Na-2 systems on the basis of a model that a spherical jellium of Na-9(+) is deformed by collision of a rare-gas atom. The total absolute cross sections are estimated by a two-step scheme: collisional excitation and dissociation. (C) 1996 American Institute of Physics.

DOI： 10.1063/1.471318

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Language：Japanese   Publisher：物性研究刊行会  

この論文は国立情報学研究所の電子図書館事業により電子化されました。

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Language：Japanese   Publisher：素粒子論グループ 素粒子研究編集部  

DOI： 10.24532/soken.92.5_E112

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Language：English   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Collision-induced reactions of Na-n(+) (n = 2-9) with Ne and Kr were investigated by means of a Tandem mass spectrometer equipped with octapole ion guide. The dominant processes were evaporation of a Na atom from Na-n(+) with even sizes or Na-2 molecules from those with odd sizes. The absolute cross section for the reaction was measured as functions of the parent-cluster size and the collision energy. The branching fractions of the daughter-ion production were also determined. These results are interpreted in a scheme of a pair interaction in jellium background.

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Collision-induced dissociation (CID) of acrylonitrile (AN: CH2=CHCN) cluster cations and anions, (AN)(n)(+/-) (n = 2-11), with an Ne or Kr atom was investigated in order to elucidate their structures. In the collision of (AN)(n)(-) with a rare gas atom, [(AN)(n)-X](-) (X = HCN, CH2CN) were produced along with (AN)(m)(-) (m less than or equal to n). The size distributions of the product anions show that (AN)(n)(-) is composed of a chemically bonded trimeric core anion solvated with chemically bonded AN trimer units and AN monomers. On the ether hand, in a 1.0-eV collision of (AN)(n)(+) with a Kr atom, (AN)(m)(+) (m less than or equal to n) were produced by evaporation of acrylonitrile molecules.

DOI： 10.1021/j100048a008

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We report the formation of dihalide products from the endothermic gas-phase ion-molecule reaction of Cl- with CH3Br at suprathermal collision energies using both guided ion beam and selected ion flow drift tube (SIFDT) techniques. The cross sections for the Cl- + CH3Br reactions were determined using the guided ion beam apparatus over a center-of-mass collision energy range of 2-15 eV with the ClBr- product displaying a maximum near 7 eV. This result is found to be in good agreement (when convoluted with the appropriate velocity distribution) with the rate constant measured by the SIFDT. ICI- and I-2(-) are also found for the Cl- + CH3I and I- + RI reactions at elevated collision energies (less than or equal to 1.5 eV) in the SIFDT. The rates for halide displacement are found to be insensitive to collision energy. These results indicate that attack on the C-X bond may nor provide an efficient alternative to the S(N)2 mechanism for halide exchange in the asymmetric X(-) + CH3Y systems. This conclusion is supported by nb initio calculations (MP2LANL10Z level) which indicate that ClBr- can be formed by collinear attack at the halogen through a Cl...Br...CH3 intermediate.

DOI： 10.1021/ja00111a023

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Dissociation dynamics of Ar cluster ions, Ar-n(+) (n = 3 - 16), in collision with He and Ne atoms was investigated by measuring the absolute dissociation cross sections and the branching fractions of the product ions at the collision energies of 0.1-10 eV in the center-of-mass frame. The cross sections and the branching fractions were successfully explained in terms of collisional excitation of the parent cluster ion and subsequent dissociation of it; the collisional excitation was treated by a hard sphere collision model with the aid of the molecular dynamics (MD) and the diatomics-in-molecules (DIM) calculations reported previously, and the subsequent dissociation was explained by the Rice-Ramsperger-Kassel (RRK) theory.

DOI： 10.1063/1.468357

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Collision of Ar cluster ions, Ar(n)+ (n = 3-16), with He and Ne atoms was investigated by use of mass spectroscopic techniques. The cross sections for the production of Ar(n')+ (n' < n) were measured as functions of the size of the parent cluster ion and the collision energy (0.1-10 eV in the center-of-mass frame). These results were analyzed in the scheme of hard-sphere spectator collision with RRK theory. It was concluded that the reaction proceeds via collisional excitation of the parent cluster ion and following sequential loss of the constituent Ar atoms.

DOI： 10.1007/BF01437834

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Dissociation of protonated methanol cluster ions, (CH3OHH+ (n = 2-23), in collision with He, Ne, or Kr atoms were studied by means of a tandem mass spectrometer equipped with octapole ion guides. The mass spectra of the product ions show that the dominant process is evaporation of CH3OH molecules from (CH3-OHH+. The absolute cross section for the evaporation was measured as functions of the cluster sizes and the collision energy in the range 0.05-100 eV in the center of mass frame. The branching fractions for the product ions were also determined. It is inferred that the evaporation proceed via the collisional excitation and subsequent unimolecular dissociation.

DOI： 10.1021/j100087a009

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The collision-induced reaction of Ar-n(+) (n=2-23) with Ar-36 was investigated at the collision energies of 0.2 and 2.0 eV. The product ions were Ar-n'(+), and (ArArn'-1+)-Ar-36 (n'<n). The absolute cross sections for the product formation were obtained as a function of the size of the parent cluster ion. The cross section for the formation of Ar-n'(+) (evaporation) increased rapidly with n in the n less than or equal to 9 range, and slowly above it; the cross section at n=23 was approximate to 180 Angstrom(2). On the other hand, the cross section for the (ArArn'-1+)-Ar-36 formation (fusion) started to rise at n=7 and increased slowly as n increases. In order to elucidate the reaction scheme, the molecular dynamics (MD) simulation based on the diatomics-in-molecules (DIM) method was performed. The reaction (evaporation and fusion) cross sections estimated from the simulation reproduced the observed ones within an accuracy of 15% at n=6, 13, and 19 at the collision energy of 0.2 eV. The following reaction scheme based on this simulation was found to explain the experimental results: collisional excitation of the parent cluster ion Ar-n(+) and subsequent unimolecular dissociation (evaporation), and formation of a collision complex (ArArn+)-Ar-36 and subsequent unimolecular dissociation (fusion). In addition, it was confirmed by the MD calculation that the fusion proceeded via perfectly inelastic collision and following evaporation in the 0.2 eV collision of Ar-10(+) with Ar-36.

DOI： 10.1063/1.467055

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Collision-induced reactions of size-selected cluster anions, (CO2)n- and (N2O)nO- with He and Kr atoms were studied at collision energies from 0.1 to 2.0 eV (center-of mass) by means of a tandem mass-spectrometer equipped with a pair of octapole ion guides. The dominant process was evaporation of the constituent molecules from the parent cluster ion. The absolute cross section for the evaporation was measured as functions of the size of the parent cluster ion and the collision energy. The reaction was explained by collisional excitation of the parent cluster ion followed by its unimolecular dissociation. The observed cross sections which correspond to those for the collisional excitation agree with those calculated in terms of charge-induced dipole and induced dipole-induced dipole interactions between the parent cluster ion and the target atom. The distributions of the product ions resulting from the unimolecular dissociation were reproduced by a simple calculation based on RRK theory. In the collision of (CO2)n-, the cross sections for (CO2)10- and (CO2)14- were significantly small and their abundances in the product ion distributions were particularly large. These findings indicate that (CO2)10- and (CO2)14- are stable species. On the other hand, stable species in (N2O)nO- was found to be (N2O)5O-.

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Collision-induced reaction of Ar(n)+ (n=2-15) with Kr was studied at collision energies from 0.1 to 2.0 eV (center-of-mass) by means of a tandem mass-spectrometer equipped with octopole ion guides. The reaction was found to proceed via Ar-atom evaporation from Ar(n)+, charge transfer from Ar(n)+ to Kr or fusion of Ar(n)+ with Kr. The absolute cross sections for these processes were measured as functions of the size of the parent cluster ion and the collision energy. The evaporation-process was explained by collisional excitation of the parent cluster ion followed by a unimolecular dissociation of the ''hot'' parent cluster ion through evaporation. The charge transfer was found to proceed most efficiently in the n less-than-or-equal-to 6 range probably because of its energetics. On the other hand, the fusion process is energetically allowed in the entire size range studied and its cross section can be approximated by the geometrical cross section of Ar(n)+.

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DOI： 10.3131/jvsj.35.668

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DOI： 10.3131/jvsj.35.668

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Using two independent vaporization lasers, bimetallic clusters composed of transition elements and Al were generated by the laser vaporization method. Reactivity toward hydrogen adsorption of bimetallic clusters was compared with genuine clusters. It was found that Al which has no reactivity toward hydrogen plays a role of either inhibitor or accelerator of the reaction when Al is mixed with Nb or Co. Unusual stability of Co12 V1 in contrast to the high reactivity of Co12-13 is attributed to the rigid geometric structure where V occupies the central position.

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Reactivity of positively charged cobalt cluster ions (Co(n)+, n = 2-22), produced by laser vaporization, with various gas samples CH4, N2, H-2, C2H4, and C2H2) were systematically investigated by using a fast-flow reactor. The reactivity of Co(n)+ with the various gas samples is qualitatively consistent with the adsorption rate of the gas to cobalt metal surfaces. Co(n)+ highly reacts with C2H2 as characterized by the adsorption rate to metal surfaces, and it indicates no size dependence. In contrast, the reactions of Co(n)+ with the other gas samples indicate a similar cluster size dependence; at n = 4, 5, and 10-15, Co(n)+ highly reacts. The difference can be explained by the amount of the activation energy for chemisorption reaction. Compared with neutral cobalt clusters, the size dependence is almost similar except for Co4+ and Co5+. The reactivity enhancement of Co4+ and Co5+ indicates that the cobalt cluster ions are presumed to have an active site for chemisorption at n = 4 and 5, induced by the influence of positive charge.

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Language：English   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/j100370a006

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The reactions of vanadium and cobalt clusters, generated by laser vaporization, with ethylene and acetylene were studied by using a fast flow reactor. In the reaction of small Vn with C2H4, the dehydrogenated products VnC2, VnC2H2 increasing the cluster number, the intensities of those products decrease monotonically, while those of VnC2H4 increase. Similar results were observed in the reaction of Vn with C2H2. On the other hand, only non-dehydrogenated products were observed in the reaction of small Con with C2H4, but for larger clusters (n ≥ 9) the dehydrogenated products ConC2 and ConC2H2 appeared. The contrast between the reaction of Vn and Con is related to the heats of adsorption and the structure of adsorbed products. © 1989.

DOI： 10.1016/0009-2614(89)87310-5

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The reactions of small alloy clusters, which are made of Al and some transition metals such as Co and Nb, with H2 were studied using a fast flow reactor. Two factors - electronic and structural - are important for activation of coadsorption of Al atoms. Addition of only one Al atom to Con clusters induced a sudden increase of reactivity even though Aln clusters hardly adsorb H2. Because valence orbitals of Al atom hybridize with upper states of the valence band of the clusters, the Al atom activates the adsorption sites on the clusters. On the contrary, upon adding one Al atom to Nb5-7, extensively reactive clusters, a sudden decrease of reactivity was observed, perhaps because the Al atom gets into their active sites and blocks chemisorption of H2 on the Nbn clusters. © 1989.

DOI： 10.1016/0009-2614(89)85232-7

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Aluminum clusters were generated by a laser vaporization method. Ionization potential of Al2 was found to be lower than that of Al. In the reaction with oxygen at high concentration, the mixed cluster Al9O7 survives predominantly as a stable cluster. Ammonia was found to be adsorbed weakly on the Aln surface. © 1989 Springer-Verlag.

DOI： 10.1007/BF01427020

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The reaction of aluminum clusters, Aln (n=7-24), formed by laser vaporization, with oxygen and ammonia was studied by using a fast flow reactor. It was found that the oxygen reacts strongly with aluminum clusters to form chemisorbed products while ammonia is adsorbed weakly with Aln in a physisorbed form. In the reaction with oxygen under multiple collision conditions, a mixed cluster, Al9O7, was found to be formed selectively. © 1988.

DOI： 10.1016/0009-2614(88)85012-7

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The electronic spectra of jet-cooled Hg-CH4, -C 2H6, -N2, and -CO complexes in the vicinity of Hg 3P1 - 1S0 were studied by means of the LIF, two-color MPI, and Hg(3P0) pump-and-probe techniques. From the observed spectra, the à and B̃ states of these complexes were characterized in analogy with those of Hg-rare gas complexes. These excited-state complexes were found to predissociate into the Hg ( 3P0) atom and the ground-state molecules. The intensity alternation of the predissociation rate with respect to the excitation of the bending vibration was newly observed for the CH4 and N2 complexes in addition to the rotational dependence of the rate. On the basis of these results and the fluorescence lifetimes, the mechanisms of the intramultiplet relaxation for these complexes were examined. It was concluded that, in the à state, the bending vibration and the rotational motion of the whole system about the symmetry axis play the crucial role in the relaxation. The relaxation from the B̃ state was interpreted by the two-step process via the à state. © 1987 American Institute of Physics.

DOI： 10.1063/1.452695

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DOI： 10.1063/1.452695

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DOI： 10.1063/1.451213

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DOI： 10.1063/1.451213

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The reaction of aluminum clusters, Aln (n=7-24), formed by laser vaporization, with oxygen and ammonia was studied by using a fast flow reactor. It was found that the oxygen reacts strongly with aluminum clusters to form chemisorbed products while ammonia is adsorbed weakly with Aln in a physisorbed form. In the reaction with oxygen under multiple collision conditions, a mixed cluster, Al9O7, was found to be formed selectively. ? 1988.

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The electronic spectra of jet-cooled Hg-CH4, -C 2H6, -N2, and -CO complexes in the vicinity of Hg 3P1 - 1S0 were studied by means of the LIF, two-color MPI, and Hg(3P0) pump-and-probe techniques. From the observed spectra, the ? and B? states of these complexes were characterized in analogy with those of Hg-rare gas complexes. These excited-state complexes were found to predissociate into the Hg ( 3P0) atom and the ground-state molecules. The intensity alternation of the predissociation rate with respect to the excitation of the bending vibration was newly observed for the CH4 and N2 complexes in addition to the rotational dependence of the rate. On the basis of these results and the fluorescence lifetimes, the mechanisms of the intramultiplet relaxation for these complexes were examined. It was concluded that, in the ? state, the bending vibration and the rotational motion of the whole system about the symmetry axis play the crucial role in the relaxation. The relaxation from the B? state was interpreted by the two-step process via the ? state. ? 1987 American Institute of Physics.

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Aluminum clusters were generated by a laser vaporization method. Ionization potential of Al2 was found to be lower than that of Al. In the reaction with oxygen at high concentration, the mixed cluster Al9O7 survives predominantly as a stable cluster. Ammonia was found to be adsorbed weakly on the Aln surface. ? 1989 Springer-Verlag.

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The reactions of small alloy clusters, which are made of Al and some transition metals such as Co and Nb, with H2 were studied using a fast flow reactor. Two factors - electronic and structural - are important for activation of coadsorption of Al atoms. Addition of only one Al atom to Con clusters induced a sudden increase of reactivity even though Aln clusters hardly adsorb H2. Because valence orbitals of Al atom hybridize with upper states of the valence band of the clusters, the Al atom activates the adsorption sites on the clusters. On the contrary, upon adding one Al atom to Nb5-7, extensively reactive clusters, a sudden decrease of reactivity was observed, perhaps because the Al atom gets into their active sites and blocks chemisorption of H2 on the Nbn clusters. ? 1989.

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The reactions of vanadium and cobalt clusters, generated by laser vaporization, with ethylene and acetylene were studied by using a fast flow reactor. In the reaction of small Vn with C2H4, the dehydrogenated products VnC2, VnC2H2 increasing the cluster number, the intensities of those products decrease monotonically, while those of VnC2H4 increase. Similar results were observed in the reaction of Vn with C2H2. On the other hand, only non-dehydrogenated products were observed in the reaction of small Con with C2H4, but for larger clusters (n ? 9) the dehydrogenated products ConC2 and ConC2H2 appeared. The contrast between the reaction of Vn and Con is related to the heats of adsorption and the structure of adsorbed products. ? 1989.

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Language：Japanese  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Language：Japanese  

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Language：Japanese  

この論文は国立情報学研究所の電子図書館事業により電子化されました。

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Language：English  

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Language：Japanese  

この論文は国立情報学研究所の電子図書館事業により電子化されました。

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Presentation type：Poster presentation  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Poster presentation  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Presentation type：Poster presentation  

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Language：Japanese  

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Language：Japanese  

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Language：Japanese  

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Language：English   Presentation type：Oral presentation (general)  

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Language：English  

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Language：Japanese  

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Language：English  

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Language：Japanese  

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Language：English  

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Language：English  

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Language：Japanese   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Type：Visiting lecture

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Type：Lecture

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Type：Other

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Type：Other

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Type：Research consultation

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Type：Visiting lecture

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Type：Visiting lecture

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