研究者詳細 - 中嶋　敦

論文 - 中嶋　敦

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Negative ion photoelectron spectroscopy of acridine molecular anion and its monohydrate

S. Kokubo, N. Ando, K. Koyasu, M. Mitsui, A. Nakajima

Journal of Chemical Physics （American Institute of Physics） 121 （ 22 ） 11112 - 11117 2004年12月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 0021-9606

Negative ion photoelectron spectroscopy was employed to investigate the electronic structure of the acridine molecular anion and its monohydrated anion in the gas phase. Their adiabatic electron affinities were measured to be 0.896±0.010 and 1.18±0.05 eV, and the low-lying electronic excited states in both neutral acridine and in its monohydrate were revealed. The photoelectron spectra clearly exhibit the presence of low-lying singlet and triplet states having a (π, π*) configuration in an uncomplexed acridine molecule. Comparison of the photoelectron spectrum of acridine with that of anthracene shows that photodetachment processes into the excited states of (n, π*) configuration have little intensity, implying a relatively large intramolecular structural relaxation in the (n, π*) states. © 2004 American Institute of Physics.

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Coexistence of two different anion states in polyacene nanocluster anions

M. Mitsui, S. Kokubo, N. Ando, Y. Matsumoto, A. Nakajima, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 121 （ 16 ） 7553 - 7556 2004年10月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 0021-9606

The coexistence of two types of anion sates in nanometer-scale polyacene cluster anions, was analyzed. Nanoclusters of naphthalene and anthracene having single excess electron were synthesized in the gas-phase. The photoelectron spectra of size-selected cluster anions containing 2 to 100 molecules exhibited rigid 'crystal-like' cluster anion in which surrounding neutral molecules reorganize around the charge core. The results show that two anion states appear to correlate to negative polaronic states formed in corresponding crystals.

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Ferromagnetism in one-dimensional vanadium-benzene sandwich clusters

K. Miyajima, A. Nakajima, S. Yabushita, M. B. Knickelbein, K. Kaya

Journal of the American Chemical Society （American Chemical Society） 126 （ 41 ） 13202 - 13203 2004年09月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 0002-7863

A molecular beam of multilayer vanadium-benzene organometallic complexes V n(C 6H 6) m was produced by a laser vaporization synthesis method. The magnetic moments of the complexes were measured by a molecular beam magnetic deflection technique, and were found to increase with the number of vanadium atoms in the cluster, showing that the unpaired electrons, which occupy the nonbonding d σ orbitals localized on the metal atoms, couple ferromagnetically. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition metal atoms are formally zerovalent. Copyright © 2004 American Chemical Society.

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Electronic structures of exohedral lanthanide-C₆₀ clusters

J. Suzumura, N. Hosoya, S. Nagao, M. Mitsui, A. Nakajima

Journal of Chemical Physics （American Institute of Physics） 121 （ 6 ） 2649 - 2654 2004年08月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 00219606

The electronic structures of several gas phase exohedral lanthanide (Ln)-C60, LnnC60 with n=1-4, clusters were discussed. it was shown that most of the Ln atoms preferably take +3 oxidation states, while Eu atoms alone assume +2 oxidation states, and that C60 accepts up to twelve donated electrons in LnnC60. The photoionization examination of the oxygen atom mixing into the Ln nC60 clusters showed that each oxygen atom reduces two electrons from C60. It was suggested that the number of accepted electrons in C60 can be varied by a suitable choice of the number of Ln atoms and O atoms.

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Photoelectron spectroscopy of pyrene cluster anions, (pyrene)_n^- (n = 1-20)

N. Ando, S. Kokubo, M. Mitsui, A. Nakajima

Chemical Physics Letters （Elsevier Science BV） 389 （ 4-6 ） 279 - 283 2004年05月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 00092614

Pyrene molecular anion and its homogeneous clusters, (pyrene) n- (n=2-20), have been studied by anion photoelectron spectroscopy. The adiabatic electron affinity (EAa) of pyrene was directly determined to be 0.406±0.010 eV. This EAa value agrees with that calculated using the method of density functional theory, showing that the excess electron occupies the lowest unoccupied molecular orbital of pyrene molecule. Photoelectron spectra of its cluster anions suggest that the excess electron in the pyrene dimer anion is delocalized over the two pyrene moieties, whereas in larger clusters the excess electron is predominantly localized on a single pyrene molecule. © 2004 Elsevier B.V. All rights reserved.

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Magnetic trapping of Co_coreCoO_shell nanoparticles produced by gas phase reaction

S. H. Huh, A. Nakajima

Chemistry Letters （Chemical Society of Japan） 33 （ 4 ） 428 - 429 2004年03月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 03667022

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Fabrication of ferromagnetic nanocluster rods by magnetic trapping

S. H. Huh, A. Nakajima, K. Kaya

Journal of Applied Physics （American Institute of Physics） 95 （ 5 ） 2732 - 2736 2004年03月

研究論文（学術雑誌）, 共著, 最終著者, 査読有り, ISSN 0021-8979

The fabrication of ferromagnetic nanocluster rods by magnetic trapping was discussed. The morphology of the produced nanomaterials was analyzed by electron microscopy and the composition by electron energy-loss spectroscopy. It was found that one dimensional structured soft magnets, up to ∼ 150 nm in length were formed consisting of magnetic clusters a few nanometers in diameter. The mechanism and driving behind their growth process and their magnetic evolution was also proposed.

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Coexistence of Solvated Electrons and Solvent Valence Anions in Negatively Charged Acetonitrile Clusters, (CH₃CN)_n^- (n = 10-100)

M. Mitsui, N. Ando, S. Kokubo, A. Nakajima, K. Kaya

Physical Review Letters （American Institute of Physics） 91 （ 15 ） 1530021 - 1530024 2003年10月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 00319007

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Band gap shiftings in Co-doped Nb_n (n = 3-15) clusters: Influence of Co 3d electrons on the electronic structure

A. Pramann, K. Koyasu, A. Nakajima, K. Kaya

International Journal of Mass Spectrometry （Elsevier Science BV） 229 （ 1-2 ） 77 - 82 2003年07月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 13873806

The photoelectron spectra of bimetallic, mass-selected Nb nCo- clusters (n = 3-15) measured at 4.66eV photon energy are reported. The electronic structure changes of the binary clusters are discussed in comparison with the electronic structures of pure Nb n- clusters as a function of size evolution. Spectroscopic parameters like electron affinities (EAs) and vertical detachment energies (VDEs) are determined. The addition of one Co atom to the Nb n cluster core significantly perturbs the electronic structures of pure Nbn clusters at small cluster sizes. Electronic state merging can be explained by hybridization of Co 3d and 4s as well as Nbn 4d-derived valence orbitals. Tentative geometric structure postulations are carried out revealing the influence of the incoming Co atom toward the intact Nbn cluster core. In strong contrast to pure Nbn clusters, a highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap closing of NbnCo at n = 6 indicates a bulk-like evolution of electronic structures induced by charge transfer of Co 3d electrons. © 2003 Elsevier B.V. All rights reserved.

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Geometric and electronic structures of metal (M)-doped silicon cluster (M = Ti, Hf, Mo and W)

M. Ohara, K. Koyasu, A. Nakajima, K. Kaya

Chemical Physics Letters （Elsevier Science BV） 371 （ 3-4 ） 490 - 497 2003年03月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 0009-2614

We have studied geometric and electronic structures of metal (M) atom doped silicon (Si) clusters, MSin (M = Ti, Hf, Mo and W), using mass spectrometry, a chemical-probe method and photoelectron spectroscopy. In the mass spectra for all of the mixed cluster anions, MSin-, both MSi15- and MSi16- were abundantly produced compared to neighbors. Together with the result of the adsorption reactivity and photoelectron spectroscopy, it has been revealed that one metal atom can be encapsulated inside a Sin cage at n ≥ 15. © 2003 Elsevier Science B.V. All rights reserved.

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The electronic structures of terbium-phthalocyanine sandwich clusters

K. Miyajima, E. Okada, A. Nakajima, K. Kaya

Chemistry Letters （Chemical Society of Japan） 32 （ 3 ） 280 - 281 2003年02月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 0366-7022

Terbium (Tb)-phthalocyanine (pc) sandwich clusters, Tbn(pc)n+1 (n = 1-4), and their Na adducts, TbNak(pc)2 (k = 1-4) were produced by dual laser vaporization of a Tb rod and the molded rod of metal-free or disodium phthalocyanine (H2pc/Na2pc) in gas phase. The minimum number of Na atoms attached to the cationic/neutral/anionic Tb1(pc)2 clusters is 2, 1, and 0, respectively. Together with the ionization energies of the Na adducts of Tb(Na)k(pc)2 (k = 1 and 2), it is revealed that the Tb-pc clusters are formed through fairly ionic bondings, where each component exists as Tb3+, Na+, and pc2-, respectively.

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Negative ion photoelectron spectroscopy of (benzene)_n^- (n = 53-124) and (toluene)_n^- (n = 33-139): Solvation energetics of an excess electron in size-selected aromatic hydrocarbon nanoclusters

M. Mitsui, A. Nakajima, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 117 （ 21 ） 9740 - 9749 2002年12月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 00219606

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Quasi-band electronic structure of V_n(benzene)_n+1 clusters

K. Miyajima, K. Muraoka, M. Hashimoto, T. Yasuike, S. Yabushita, A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 106 （ 45 ） 10777 - 10781 2002年08月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 10895639

Photoionization efficiency (PIE) curves were measured for sandwich vanadium-benzene clusters, Vn(benzene)n+1 (n = 1-5), which were produced by the reaction of laser-vaporized vanadium atoms with benzene vapor. A two-rod laser vaporization source was used for enhancing the production of the larger clusters. The second lowest ionization energies of the sandwich clusters were probed experimentally for the first time. The PIE curves of the sandwich clusters clearly present evidence that the clusters take a quasi-band electronic structure which results from a one-dimensional sandwich structure.

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Electronic structures of Ho_nC₆₀ clusters (n = 1-5): High electron acceptability of C₆₀

S. Nagao, Y. Negishi, A. Kato, Y. Nakamura, A. Nakajima, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 117 （ 7 ） 3169 - 3172 2002年08月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 00219606

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Photoelectron spectroscopy of palladium-doped gold cluster anions; Au_nPd^- (n = 1-4)

K. Koyasu, M. Mitsui, A. Nakajima, K. Kaya

Chemical Physics Letters （Elsevier Science BV） 358 （ 3-4 ） 224 - 230 2002年05月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 00092614

Palladium-doped gold clusters, AunPd- (n = 1-4), were investigated using anion photoelectron spectroscopy at 4.66 eV photon energy. Electron affinities (EAs) and vertical detachment energies (VDEs) are determined, and the electronic structures of Pd-doped Aun clusters are compared to those of pure Aun clusters. A peak shape analysis reveals electronic and geometric similarity between Aun- and Aun-1Pd- clusters and it is found that (1) an electron promotion occurs from 4d to 5s orbital in the Pd atom, and that (2) the bond of Au-Pd is formed through σ orbital between 6s of Au and 5s of Pd. © 2002 Published by Elsevier Science B.V.

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Photoelectron spectroscopy of cobalt oxide cluster anions

A. Pramann, K. Koyasu, A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 106 （ 19 ） 4891 - 4896 2002年04月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 1089-5639

Photoelectron spectroscopy of size-selected ConOm- clusters (n = 4-20; m = 0-2) is performed in a pulsed molecular beam experimental at photon energies of 3.49 and 4.66 eV. Cobalt oxide cluster anions are generated in a laser vaporization source and the photoelectron spectra are measured with a magnetic bottle photoelectron spectrometer. The size-dependent evolution of the electronic structure of the oxide clusters is discussed in terms of cluster composition. Threshold binding energy features are mainly contributed from Co d-derived orbitals throughout the complete series, indicating that the incoming oxygen atoms cause a minor influence on the electronic structures. Although for n > 13 EAs and VDEs of Con and ConOm clusters overlap within the experimental resolution, at smaller cluster sizes, the values increase in the order of Con < ConO < ConO2. For Co4O3- and Co5O3-, the spectra indicate the presence of isomers with low EAs peroxo and ozonide isomers. To compare the different channels of oxygen chemisorption, relative dissociation energies are determined via thermochemical cycles.

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Anion photoelectron spectroscopy of V_nO_m^- (n = 4-15; m = 0-2)

A. Pramann, K. Koyasu, A. Nakajima, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 116 （ 15 ） 6521 - 6528 2002年04月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 00219606

Anion photoelectron spectroscopy was used to study small negatively charged vanadium oxide clusters at 4.66 eV photon energy. The electronic structure of the vanadium clusters was investigated as a function of size n and composition m. The changes of the electronic structure of the vanadium cluster cores after adding two oxygen atoms were examined. Thermomechanical cycles were used to determine relative dissociation energies for different oxygen-loss channels from the parent clusters. Electron affinities and vertical detachment energies were found to increase with increasing cluster size.

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Behavior of silicon and germanium clusters on a C₆₀ fullerene

M. Ohara, Y. Nakamura, Y. Negishi, K. Miyajima, A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 106 （ 18 ） 4498 - 4501 2002年04月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 10895639

Behavior of silicon (Si) and germanium (Ge) atoms (or clusters) on the surface of a C60 fullerene has been revealed by using time-of-flight mass spectroscopy and photoelectron spectroscopy. The mixed clusters of C60Sin and C60Gem were generated by two-lasers vaporization of a molded C60 rod and a Si (or a Ge) rod in He carrier gas. The size distributions of anionic and cationic C60Sin/C60Gem clusters monotonically decreased with the number of Si/Ge atoms, and were limited only up to n = 4 and m = 3. The photoelectron spectra of C60Sin- and C60Gem- are similar to that of pure C60- at m = 3, 4, whereas the spectra at n, m = 1, 2 are different from that of C60-. These results show that Si/Ge atoms assemble together into Si/Ge clusters on the C60 cage with an increase in the number of Si/Ge atoms.

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Anion photoelectron spectroscopy of vanadium-doped cobalt clusters

Pramann A., Koyasu K., Nakajima A., Kaya K.

Journal of Physical Chemistry A （AMER CHEMICAL SOC） 106 （ 11 ） 2483 - 2488 2002年03月

研究論文（学術雑誌）, 査読有り, ISSN 1089-5639

Bimetallic cobalt (Co)-vanadium (V) clusters, ConVm- (n = 4-14, m = 0-2), are investigated using anion photoelectron spectroscopy at 4.66 eV photon energy. Electron affinities (EA) and vertical detachment energies (VDE) are determined, and the electronic structures of V- and V2-doped Con clusters are compared to those of pure Con clusters. Bonding and hybridization effects can be explained using a charge-transfer model. A peak shape analysis confirms the high stability of the Co12V cluster with a most plausible icosahedral structure with the V atom in the cage center. Together with ionization potentials (IP), the electronic structures of the clusters are compared to H2 chemisorption rate coefficients reported previously. Thus, this study completes the investigation of electronic properties and reactivity of the bimetallic ConVm clusters as a function of charge, size, and distribution. Although the reactivity of ConVm reveals a better correlation toward the EA rather than toward IP, no improved correlation is found between promotion energies and reactivity. This result clearly shows that the chemisorption reactivity of the heterogeneous clusters is largely governed by geometric factors.

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Geometric and electronic structures of terbium-silicon mixed clusters (TbSi_n; 6 ≤ n ≤ 16)

M. Ohara, K. Miyajima, A. Pramann, A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 106 （ 15 ） 3702 - 3705 2002年03月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 10895639

The geometric and the electronic structures of terbium-silicon anions, TbSin- (6 ≤ n ≤ 16) were investigated by using photoelectron spectroscopy (PES) and a chemical-probe method. The clusters were produced by a double-rod laser vaporization technique. From trends observed in the electron affinities (EAs), the TbSin- clusters were categorized into three groups of (I) 6 ≤ n ≤ 9, (II) n = 10, 11, and (III) n ≥ 12. Together with adsorption reactivity toward H2O it is concluded that a Tb atom is encapsulated inside a Sin cage at n ≥ 10; Tb@Sin.

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中嶋 敦

論文 - 中嶋 敦

中嶋　敦

論文 - 中嶋　敦