研究者詳細 - 中嶋　敦

論文 - 中嶋　敦

分割表示 258 件中 181 - 200 件目／全件表示 >>

Multiple-decker sandwich poly-ferrocene clusters

S. Nagao, A. Kato, A. Nakajima, K. Kaya

Journal of the American Chemical Society （American Chemical Society） 122 （ 17 ） 4221 - 4222 2000年04月

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

Access to Document (DOI)

Visible and Infrared Photoluminescence from Deposited Germanium-Oxide Clusters and from Ge Nanocrystals

A. Nakajima, M. Fujii, S. Hayashi, K. Kaya

L. Pavesi and E. Buzaneva (eds.)“Frontiers of Nano-Optoelectronic Systems: Molecular Scale Engineering and Processes” (Proceeding of NATO/EC Advanced Research Workshop) （World Scientific） 303 - 317 2000年

研究論文（研究会，シンポジウム資料等）, 共著, 筆頭著者, 責任著者, 査読有り

Access to Document (DOI)

Photoelectron spectroscopy of tin and lead cluster anions: Application of halogen-doping method

Y. Negishi, H. Kawamata, A. Nakajima, K. Kaya

Journal of Electron Spectroscopy and Related Phenomena （Elsevier Science BV） 106 （ 2-3 ） 117 - 125 1999年12月

研究論文（学術雑誌）, 共著, 責任著者, 査読有り, ISSN 03682048

Electronic properties of tin (Sn) and lead (Pb) cluster anions were studied using photoelectron spectroscopy (PES) with a magnetic bottle-type electron spectrometer, where the feasibility of a halogen-doping method we recently developed was explored. The binary cluster anions containing a chlorine atom (Cl) were produced by a laser vaporization of a target rod in a He carrier gas mixed with a small amount of CCl4 gas. Comparing the PES of SnnCl- and those of Sn-n, it was found that the doped Cl atom in SnnCl- deprives each Sn-n cluster of the excess electron without any serious rearrangement of the Snn framework, which is similar to our previous work on SinF- and GenF-. The halogen-doping method enables us to reveal the HOMO-LUMO gap of the corresponding neutral cluster of the Snn clusters, showing that the Snn clusters are semiconductor clusters, especially below n=30, similar to the Sin and the Gen clusters. For the Pbn clusters, however, the halogen-doping method was inapplicable, which implies that the Pbn clusters are different from the other group-14 clusters, probably exhibiting a metallic nature. © 2000 Elsevier Science B.V. All rights reserved.

Access to Document (DOI)

A Novel Network Structure of Organometallic Clusters in the Gas Phase

A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 104 （ 2 ） 176 - 191 1999年12月

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

In the gas phase, novel network structures were found in organometallic clusters between metal atoms produced by laser ablation and organic ligand molecules. For 3d metal-benzene, MnBzm, two kinds of structures of multiple sandwich and rice-ball were formed, depending on the metal elements. Early transition metals (ME) of Sc, Ti, and V form the multiple-decker sandwich structure of (n, m) = (n, n + 1) in which metal atoms and benzene are alternately piled up, while late transition metals (ML) of Fe, Co, and Ni form the rice-ball structure in which central metal clusters were fully covered by benzene molecules. The ionization energy of ME-Bz drops significantly with increasing layers, which can be explained by delocalization of d electrons along the molecular axis. M-C60 binary clusters were also generated by a two-laser vaporization method; ME-C60 clusters efficiently form a chain or a ring structure consisting of a dumbbell unit, in which metal atoms and C60 are alternately connected. For ML-C60 clusters, however, the metal atom is tricapped by C60 and a face-centered tetrahedron structure is formed at (n, m) = (4, 4). A similar multiple-decker sandwich structure is formed also between lanthanide metal atoms (Ln) and an organic ligand of cyclooctatetraene (COT). The Ln-COT cluster is a charge transferred cluster consisting of positively charged Ln and negatively charged COT. Their electronic structure is fairly ionic and is localized around each metal atom. These novel structures of organometallic clusters should inspire new thoughts in material science because it is hoped that the regular arrangement of metal ions can introduce useful properties such as electroconductivity and magnetism.

Access to Document (DOI)

Generation and electronic properties of lanthanide-cyclooctatetraene organometallic clusters in gas phase

T. Kurikawa, Y. Negishi, F, Hayakawa, S. Nagao, K. Miyajima, A. Nakajima, K. Kaya

European Physical Journal D （Springer） 9 （ 1-4 ） 283 - 287 1999年12月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 1434-6060

Organometallic clusters of lanthanide (Ln = Nd, Er, Eu, and Yb) and 1,3,5,7-cyclooctatetraene (C8H8) were produced by a combination of laser vaporization and molecular beam methods. In the mass spectra of [Lnn,(C8H8)m], compositions of m = n + 1 were magic numbers. From mass spectrometry, photo-ionization spectroscopy, and photoelectron spectroscopy, we have concluded that these magic-numbered clusters take multiple-decker sandwich structures in which Ln atoms and C8H8 molecules are alternatedly piled up. These sandwich clusters are formed through ionic bonds composed of multiply charged cations [Lnk+ (k = 2 and 3)] and multiply charged anions [C8Hh-8 (h = 1, 1.5, and 2)].

Access to Document (DOI)

Photoelectron spectroscopy of 7-azaindole-water cluster anions

A. Nakajima, Y. Negishi, R. Hasumi, K. Kaya

European Physical Journal D （Springer） 9 （ 1-4 ） 303 - 307 1999年12月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 1434-6060

The 7-azaindole (7-AzI) cluster anions and their H2O adducts were generated by electron attachment to the 7-AzI/7-AzI-H2O clusters, and their electronic properties studied with mass spectrometry and photoelectron spectroscopy. In the mass spectra of the 7-AzI cluster anions, (7-AzI)-n, monomer anions were missing due to negative electron affinity (EA), while clusters (n ≥ 2) have positive EA, and those having even n were more abundant than those at odd n. EA increased with cluster size from 0.88 eV at n = 2, and an even-odd alternation in the EA was seen. The even-odd alternation showed that the 7-AzI dimer acts as a unit for cluster formation. In the photoelectron spectrum of (7-AzI)-2 at 266 nm, the second peak was observed 2.4 eV above the first peak; this is attributed to the triplet state of the neutral (7-AzI)2. Depending on the detachment energy, a movable peak, with the detachment of 420-300 nm (2.9-4.1 eV), was additionally observed between the first and the second peaks; this was thought to be caused by a delayed photoemission via an electronic excited state of the (7-AzI)-2 anion.

Access to Document (DOI)

Pyramidal Structures of Lanthanide-C₆₀ Clusters (Ln_n(C₆₀)_m: Ln = Eu and Ho)

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

Journal of Physical Chemistry A （American Chemical Society） 103 （ 45 ） 8909 - 8914 1999年10月

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

Novel lanthanide organometallic clusters, Lnn(C60)m, consisting of lanthanide atoms (Ln; Ln = Eu and Ho) and C60 molecules were produced in gas phase by a two-laser vaporization method. The Lnn(C60)m clusters were produced predominantly at compositions of (n, m) = (n, n + 3) [n = 1-4]. These stoichiometries showed no chemisorption reactivity toward CCl4 and O2 reactants. The cluster having (1,4) composition is proposed to form a tetrahedral structure, in which a Ln atom is surrounded by four C60 molecules. In larger clusters with (n, n + 3) composition, each Ln atom is found in a local (1,4) group. Together with the results of sequential chemisorption of Cl atoms on cluster cations, photoelectron spectroscopy of cluster anions leads us to conclude that Ln1(C60)m clusters are charge-transfer complexes expressed as Ln1x+(C60)mx-, and that Eu and Ho atoms exist as Eu2+ and Ho3+ ions, respectively.

Access to Document (DOI)

Photoelectron spectroscopy of sodium-coated C₆₀ and C₇₀ cluster anions

B. Palpant, A. Otake, F. Hayakawa, Y. Negishi, G. H. Lee, A. Nakajima, K. Kaya

Physical Review B - Condensed Matter and Materials Physics （American Institute of Physics） 60 （ 7 ） 4509 - 4512 1999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 10980121

A systematic study of photoelectron spectroscopy for C60Na-N (N=0–33) and C70Na-N (N=0–15) clusters is reported. These clusters are produced by a laser vaporization source and their photoelectron spectrum is measured using a magnetic-bottle time-of-flight spectrometer. For N < 13, the adiabatic electron affinity and the vertical detachment energy display strong regular features with increasing N. A packing of the sodium atoms in stable Na3 trimers is inferred, with each atom lying above a pentagonal ring. For larger clusters (N>13), a very different trend is observed, signing the appearance of a metallic behavior for the sodium layer at the fullerene surface. The specific case of C70 is also discussed. © 1999 The American Physical Society.

Access to Document (DOI)

Production of jet-cooled coronene and coronene cluster anions and their study with photoelectron spectroscopy

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

Chemical Physics Letters （Elsevier Science BV） 309 （ 1-2 ） 49 - 54 1999年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0009-2614

Anions of coronene (C24H12) and its clusters are produced by laser ablation of a pressed pellet sample in a double rod, pulsed nozzle source. Coronene anions are produced efficiently only when transition metal vapor is present in the same plasma from co-vaporization of a metal sample. Anion monomers and clusters of coronene are size-selected and studied with photoelectron spectroscopy in a magnetic bottle spectrometer. Spectra at 532, 355 and 266 nm probe electron affinities and neutral electronic states. The electron affinity of coronene is 0.47±0.09 eV and that of coronene dimer is 0.67±0.09 eV.

Access to Document (DOI)

Charge distributions in multiple-decker sandwich clusters of lanthanide-cyclooctatetraene: Application of Na-atom doping

K. Miyajima, T. Kurikawa, M. Hashimoto, A. Nakajima, K. Kaya

Chemical Physics Letters （Elsevier Science BV） 306 （ 5-6 ） 256 - 262 1999年06月

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

In gas phase, Na-atom adducts were produced for organometallic lanthanide complexes of Lnn(C8H8)n+1 [Ln = europium (Eu) and holmium (Ho); C8H8 = 1,3,5,7-cyclooctatetraene (COT)] by a combination of two-laser vaporization and a molecular beam method. The number of attached Na atoms can be reasonably explained by charge distributions of the complex, where Eu and Ho atoms exist as Eu2+ and Ho3+ , respectively, and C8H8 molecules as COT2-, accepting two excess electrons. The behavior of the Na adducts chemically demonstrates that the organometallic lanthanide complex is formed through ionic bonding, implying that it is possible to be isolated as its Na salt. © 1999 Elsevier Science B.V. All rights reserved.

Access to Document (DOI)

Electronic properties of organometallic metal-benzene complexes [M_n(benzene)_m (M = Sc-Cu)]

T. Kurikawa, H. Takeda, M. Hirano, K. Judai, T. Arita, S. Nagao, A. Nakajima, K. Kaya

Organometallics （American Chemical Society） 18 （ 8 ） 1430 - 1438 1999年03月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 02767333

Neutral metal-benzene complexes, Mn(benzene)m (M = Sc to Cu), are produced for all of the 3d transition metals in the gas phase by using the laser vaporization method. These species are characterized by mass spectrometry, photoionization spectroscopy, and chemical probe experiments. Depending on the metal, there are two types of structures for Mn(benzene)m: multiple-decker sandwich structures and metal clusters fully covered with benzene molecules (rice-ball structures). The former sandwich structure is characteristic of the complexes for early transition metals (Sc-V), whereas the latter is formed for late transition metals (Fe-Ni). Electronic structures of M1(benzene)x (x = 1, 2) complexes are investigated through systematic measurements of ionization energies (Ei's).

Access to Document (DOI)

Photoelectron spectra of small nanophase W metal cluster anions

G. H. Lee, S. H. Huh, Y. C. Park, F. Hayakawa, Y. Negishi, A. Nakajima, K. Kaya

Chemical Physics Letters （Elsevier Science BV） 299 （ 3-4 ） 309 - 314 1999年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0009-2614

We have recorded photoelectron spectra of Wn- (n=20-90) using a magnetic bottle type photoelectron spectrometer. Each photoelectron spectrum consists of a single, broad peak, shifted successively towards a higher electron binding energy (EBE) with increasing n. We estimated the threshold EBEs from the spectra. The threshold EBE versus n-1/3 plot showed a straight line and was extrapolated to 4.50 eV which is consistent with the W bulk work function, 4.55 eV. We also estimated the bond dissociation energies of Wn- cluster anions using a simple energetic model.

Access to Document (DOI)

Multiple-decker sandwich complexes of lanthanide 1,3,5,7- cyclooctatetraene [Ln_n(C₈H₈)_m] (Ln = Ce, Nd, Eu, Ho, and Yb); localized ionic bonding structure

T. Kurikawa, Y. Negishi, F. Hayakawa, S. Nagao, K. Miyajima, A. Nakajima, K. Kaya

Journal of the American Chemical Society （American Chemical Society） 120 （ 45 ） 11766 - 11772 1998年10月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00027863

Organometallic lanthanide complexes of Ln(n)(C8H8)(m) (Ln = lanthanide metals of Ce, Nd, Eu, Ho, and Yb; C8H8 := 1,3,5,7-cyclooctatetraene) were produced by a combination of laser vaporization and molecular beam methods. The complexes having (n, m) = (n, n + 1) for n = 1-5 were prominently produced as magic numbers in the mass spectra. Using mass spectrometry, photoionization spectroscopy, and photoelectron spectroscopy, it is concluded that these magic-numbered complexes form multiple decker sandwich structures in which Ln atoms and C8H8 molecules are alternately piled up. The obtained spectroscopic data show that these sandwich complexes are formed through ionic bonds and are charge transfer complexes, where the Ln atoms are multiply charged cations of Ln(k+) (k = 2 and 3) and C8H8 molecules are multiply charged anions.

Access to Document (DOI)

The infrared HOMO-LUMO gap of germanium clusters

Y. Negishi, H. Kawamata, F. Hayakawa, A. Nakajima, K. Kaya

Chemical Physics Letters （Elsevier Science BV） 294 （ 4-5 ） 370 - 376 1998年09月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0009-2614

Access to Document (DOI)

Formation and structures of transition metal-C₆₀ clusters

S. Nagao, T. Kurikawa, K. Miyajima, A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 102 （ 24 ） 4495 - 4500 1998年05月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10895639

Transition metal (Sc, Ti, V, and Cr)-C60 binary clusters were produced in the gas phase by a two-laser vaporization method. In the mass spectra of cationic Mn(C60)m+, for M = Sc, Ti, and V, clusters having the composition of (n, m) = (1, 1)+, (1, 2)+, (2, 3)+, (3, 4)+, (4, 4)+, and (5, 5)+ were predominantly produced. The peaks having (n, n + 1)+ compositions are explicable in terms of multiple dumbbell structures, in which metal atoms and C60 are alternately stacked. Clusters with composition (4, 4)+ and (5, 5)+ are presumed to be ring structures. For Crn(C60)m+, however, a Cr atom is surrounded by three C60, forming a tricapped structure, and the structure acts as a unit for larger stable clusters of (2, 4)+, (3, 4)+, and (4, 4)+. Ionization energy measurements for neutral Mn(C60)m and a chemical probe method using CO, O2, and C2H4 as reactants gave information concerning the geometrical and electronic structures.

Access to Document (DOI)

Geometric and electronic structures of fluorine bound silicon clusters

R. Kishi, Y. Negishi, H. Kawamata, S. Iwata, A. Nakajima, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 108 （ 19 ） 8039 - 8058 1998年05月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0021-9606

Geometries and energies of SinF- and SinF (n=1-7) were investigated with ab initio MO calculations; the Møller-Plesset perturbation and coupled cluster methods were used to take into account the electron correlation. The F atom is bound to the apex atom in the Sin frame, and the electronic structures of the Sin part in SinF- and SinF are similar to those of the corresponding Sin and Si+n, respectively. The calculated electron affinities (EAs) of SinF are in agreement with the experimental values. The size dependence of EAs of SinF is similar to that of the ionization energies of Sin at n≥5, whereas it is different at n≤4. In the HOMO of SinF (n≤4), the weak antibonding nature between F and Si greatly makes the SinF- anions unstable, resulting in small EA. The vibrationally resolved photoelectron spectra (PES) of SinF- (n=1-3) were measured, and were completely reproduced theoretically. © 1998 American Institute of Physics.

Access to Document (DOI)

Formation of cobalt-C₆₀ clusters: Tricapped Co(C₆₀)₃ unit

T. Kurikawa, S. Nagao, K. Miyajima, A. Nakajima, K. Kaya

Journal of Physical Chemistry A （American Chemical Society） 102 （ 10 ） 1743 - 1747 1998年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10895639

Cobalt (Co)-C60 mixed clusters were produced by the combination of laser vaporization and molecular beam methods. Cationic Con(C60)m+ clusters were produced predominantly with the compositions (n, m) = (0-1, 1), (1, 2), (1, 3), (2-4, 4), and (5, 5). Both mass spectrometry and a chemical probe method have revealed that compositions of (1, 3) and (4, 4) correspond to a tricapped planar structure and a tricapped trigonal pyramid structure, respectively, in which each Co atom is surrounded by three C60.

Access to Document (DOI)

Geometric and electronic structures of silicon-sodium binary clusters. II. Photoelectron spectroscopy of Si_nNa_m^- cluster anions

R. Kishi, H. Kawamata, Y. Negishi, S. Iwata, A. Nakajima, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 107 （ 23 ） 10029 - 10043 1997年12月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00219606

Electronic properties of silicon-sodium cluster anions (SinNam-,; 4≤n≤11, 1≤m≤3) were investigated by photoelectron spectroscopy using a magnetic-bottle type electron spectrometer. The electron affinities (EAs) of SinNam were determined from the threshold energies in the photoelectron spectra of SinNam-. Besides, the geometries and energies of SinNa- (n=1-7) were investigated with ab initio MO (molecular orbital) calculations; Møller-Plesset perturbation and coupled cluster methods were used to take into account the electron correlation. By an Na adsorption on Sin, the EA decreases for n=4-6, but increases for n≥7. The calculations for SinNa- show that the Sin framework for n=4-6 accepts at least two excess electrons. For Si7Na-, however, the charge transfer from the Na atom scarcely occurs to avoid distorting the close-packed Si7 framework. Moreover, the ionization energy (Ei) and EA of SinNam, show several patterns with the number of the Na atoms, which reflect the charge transfer mechanism in the cluster reflecting the nature of the electron-accepting orbitals of the corresponding Sin and the adsorption types of the Na atoms. © 1997 American Institute of Physics.

Access to Document (DOI)

Ab initio MO studies of neutral and anionic SiC_n clusters (n = 2-5)

M. Gomei, R. Kishi, A. Nakajima, S. Iwata, K. Kaya

Journal of Chemical Physics （American Institute of Physics） 107 （ 23 ） 10051 - 10061 1997年12月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00219606

The geometries and energies of SiCn and SiCn (n=2-5) were investigated with ab initia calculations including electron correlation effects with the MP2/6-31G* method, followed by MP4 and CCSD(T) single-point calculations to determine the most stable isomers. The adiabatic electron affinities (AEA) were evaluated with the ΔMP4 method. Because of the complexity of the electronic structure of SiC2, its AEA was calculated at the CCSD(T)/aug cc-pVTZ//CCSD(T)/aug cc-pVDZ level of approximation. For the neutral SiCn clusters, the isomer having a triplet ground state has large EA, whereas the isomer having a singlet ground state has small EA. This is attributed to the bonding character between Si and C atoms in the orbital occupied by the extra electron. The calculated EA was used to assign the photoelectron spectra of SiCn- reported previously. Furthermore, the effects of Renner-Teller splitting for the linear isomers of anions are discussed. © 1997 American Institute of Physics.

Access to Document (DOI)

Study on iron-sulfur cluster in gas phase: Electronic structure and reactivity

A. Nakajima, T. Hayase, F. Hayakawa, K. Kaya

Chemical Physics Letters （Elsevier Science BV） 280 （ 3-4 ） 381 - 389 1997年12月

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

In gas phase, electronic and geometric properties of iron-sulfur cluster (FenSm, n=1-8, m=2-6) have been investigated using photoelectron spectroscopy (PES) of their anions and a chemical probe method for their cations. The electron affinities of FenSm greatly change at the composition of n=m, and the reactivity of FenSm+ toward NH3 and C2H2 is enhanced around equally mixed compositions. These results show that the FenSm clusters produced in gas phase seemingly take the structure having alternate bonds between Fe and S atoms, likewise that of an active site of iron-sulfur proteins.

Access to Document (DOI)

　前のページ - 次のページ　

中嶋 敦

論文 - 中嶋 敦

中嶋　敦

論文 - 中嶋　敦