研究者詳細 - 中嶋　敦

論文 - 中嶋　敦

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Anion photoelectron spectroscopy of transition metal- and lanthanide metal-silicon clusters: MSi_n^- (n = 6-20)

K. Koyasu, J. Atobe, S. Furuse, A. Nakajima

Journal of Chemical Physics （American Institute of Physics） 129 （ 21 ） 214301 - (7 pages) 2008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 00219606

The electronic properties of silicon clusters containing a transition or lanthanide metal atom from group 3, 4, or 5, M Sin, (M=Sc, Ti, V, Y, Zr, Nb, Lu, Tb, Ho, Hf, and Ta) were investigated by anion photoelectron spectroscopy at 213 nm. In the case of the group 3 elements Sc, Y, Lu, Tb, and Ho, the threshold energy of electron detachment exhibits local maxima at n=10 and 16, while in case of the group 4 elements Ti, Zr, and Hf, the threshold energy exhibits a local minimum at n=16, associated with the presence of a small bump in the spectrum. These electronic characteristics of M Sin are closely related to a cooperative effect between their geometric and electronic structures, which is discussed, together with the results of experiments that probe their geometric stability via their reactivity to H2O adsorption, and with theoretical calculations. © 2008 American Institute of Physics.

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Soft-landing isolation of gas-phase-synthesized transition metal-benzene complexes into a fluorinated self-assembled monolayer matrix

S. Nagaoka, K. Ikemoto, T. Matsumoto, M. Mitsui, A. Nakajima

Journal of Physical Chemistry C （American Chemical Society） 112 （ 40 ） 15824 - 15831 2008年09月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 1932-7447

Gas-phase-synthesized chromium-benzene 1:2 sandwich cation complexes [Cr+(benzene)2] were soft-landed on a self-assembled monolayer (SAM) of fluorinated alkanethiol (C10F-SAM) at a hyperthermal collision energy of ∼20 eV. The adsorption properties and thermal stability of the soft-landed complexes were studied with infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). The landed complexes were neutralized due to charge transfer from the SAM substrate, but their native sandwich structure remained intact. The hyperthermal collision event resulted in the penetration of the incoming complexes into the C10F-SAM matrix. The embedded complexes then tended to orient their molecular axes approximately along the surface normal. This orientational preference is measurably different from that of complexes isolated in alkanethiol SAM matrices, a discrepancy that might be caused by a repulsive interaction between the n cloud of the capping benzene rings of the complex and the side-chain CF2 groups of the fluorocarbon chains in the C10F-SAM matrix. The thermal desorption study showed that the complexes supported inside the C10F-SAM could resist thermal desorption until the high-temperature region of ∼320 K, a persistence revealing a large desorption activation energy (∼190 kJ/mol). © 2008 American Chemical Society.

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Infrared Spectroscopy and Thermal Desorption Study of Vanadium-Mesitylene 1:2 Sandwich Clusters Soft-Landed onto a Long-Chain n-Alkanethiolate Self-Assembled Monolayer

M. Mitsui, S. Doi, K. Ikemoto, S. Nagaoka, A. Nakajima

J.-P. Connerade and A. Solov’yov (eds.) "Latest Advances in Atomic Cluster Collisions (the Proceedings of ISACC 2007)" （Imperial College Press, London.） 199 - 204 2008年09月

研究論文（国際会議プロシーディングス）, 共著, 最終著者, 責任著者, 査読有り

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Mass spectroscopic study of metal-rich K_2-5(KI)_n⁺ nanoclusters

S. H. Huh, H. S. Jeong, K. Koyasu, K. Miyajima, M. Mitsui, A. Nakajima

Journal of Molecular Structure （Elsevier Science BV） 886 （ 1-3 ） 39 - 42 2008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 00222860

Metal-rich K1 - 5 (KI)n+ (n ∼27) clusters were produced by the supersonic cooling expansion of laser-induced KI plasma. The obtained mass spectroscopic peaks show the unique magic numbers at n = 9, 13, and 22 for K1(KI)n; n = 8, 12, and 21 for K2(KI)n; n = 8, 12, 16, and 21 for K3(KI)n; n = 7, 9, 11, and 13 for K4(KI)n; and n = 12 and 21 for K5(KI)n. These magic numbers are fairly different from those of other reported metal-rich Na1 - 9 (NaF)n+ and Cs1 - 5 (CsI)n+ clusters. It is interesting to note that K2, 3, 5 (KI)n+ clusters have the same magic numbers at n = 12 and 21 and possess structures that are closely related to the 3 × 3 × 3 and 3 × 3 × 5 cubic structures with the excess electron at the side anion vacancy or the center anion vacancy. © 2007 Elsevier B.V. All rights reserved.

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Experimental and theoretical characterization of MSi₁₆^-, MGe₁₆^-, MSn₁₆^-, and MPb₁₆^- (M=Ti, Zr, and Hf): The role of cage aromaticity

S. Furuse, K. Koyasu, J. Atobe, A. Nakajima

Journal of Chemical Physics （American Institute of Physics） 129 （ 6 ） 064311 - (6 pages) 2008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

Silicon (Si), germanium (Ge), tin (Sn), and lead (Pb) clusters mixed with a group-4 transition metal atom [M=titanium (Ti), zirconium (Zr), and hafnium (Hf)] were generated by a dual-laser vaporization method, and their properties were analyzed by means of time-of-flight mass spectroscopy and anion photoelectron spectroscopy together with theoretical calculations. In the mass spectra, mixed neutral clusters of M Si16, M Ge16, and M Sn16 were produced specifically, but the yield of M Pb16 was low. The anion photoelectron spectra revealed that M Si16, M Ge16, and M Sn16 neutrals have large highest occupied molecular orbital-lowest unoccupied molecular orbital gaps of 1.5-1.9 eV compared to those of M Pb16 (0.8-0.9 eV), implying that M Si16, M Ge16, and M Sn16 are evidently electronically stable clusters. Cage aromaticity appears to be an important determinant of the electronic stability of these clusters: Calculations of nucleus-independent chemical shifts (NICSs) show that Si16 4-, Ge16 4-, and Sn16 4- have aromatic characters with negative NICS values, while Pb16 4- has an antiaromatic character with a positive NICS value. © 2008 American Institute of Physics.

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Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-ternhenyl cluster anions: The effect of molecular shape on molecular assembly and ion core character

M. Mitsui, N. Ando, A. Nakajima

Journal of Physical Chemistry A （American Chemical Society） 112 （ 25 ） 5628 - 5635 2008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 10895639

Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions, (0-TP)n- (n = 2-100), (m-TP) n- (n = 2-100), and (p-TP)n- (n = 1-100), respectively, are conducted to investigate the effect of molecular shape on the molecular aggregation form and the resultant ion core character of the clusters. For (o-TP)n- and (m-TP)n-, neither magic numbers nor discernible isomers are observed throughout the size range. Furthermore, their vertical detachment energies (VDEs) increase up to large n and depend linearly on n-1/3, implying that they possess a three-dimensional (3D), highly reorganized structure encompassing a monomelic anion core. For (p-TP)n-, in contrast, prominent magic numbers of n = 5, 7, 10, 12, and 14 are observed, and the VDEs show pronounced irregular shifts below n = 10, while they remain constant above n = 14 (isomer A). These results can be rationalized with two-dimensional (2D) orderings of p-TP molecules and different types of 2D shell closure at n = 7 and 14, the monomelic and multimeric anion core, respectively. Above n = 16, the new feature (isomer B) starts to appear at the higher binding side of isomer A, and it becomes dominant with n, while isomer A gradually disappears for larger sizes. In contrast to isomer A, the VDEs of isomer B continuously increase with the cluster size. This characteristic size evolution suggests that the transition to modified 2D aggregation forms from 2D ones occurs at around n = 20. © 2008 American Chemical Society.

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Nanogranular structures formed by combinatorial control processing of size-selected metal nanoparticles

S. H. Huh, D. Riu, C. Kim, Y. Naono, T. Nakamura, A. Sugiyama, A. Nakajima

Journal of Applied Physics （American Institute of Physics） 103 （ 9 ） 094317 - (7 pages) 2008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 0021-8979

Nanogranular films and lines, which are composed of size-selected Au, Ni, and Pt nanoparticles (NPs) and which exhibit an intermediate structure between that of the individual NPs and that of polycrystalline ones, were produced by a fully physical process. By using a combination of techniques such as lithography, lift-off, size selection, and aerosol deposition, well-designed Au lines (linewidth W=80 nm) and thickness-controlled rectangular patterns could be produced, while Ni and Pt NPs did not form continuous lines if the linewidth was less than W=150 nm. This difference might be explained by the extent of collision-induced surface melting during NP deposition onto the substrate. © 2008 American Institute of Physics.

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Photoelectron spectroscopy of cluster anions of naphthalene and related aromatic hydrocarbons

N. Ando, M. Mitsui, A. Nakajima

Journal of Chemical Physics （American Institute of Physics） 128 （ 15 ） 154318 - (8 pages) 2008年04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

The electronic structures and structural morphologies of naphthalene cluster anions, (naphthalene) n- (n=3-150), and its related aromatic cluster anions, (acenaphthene) n- (n=4-100) and (azulene) n- (n=1-100), are studied using anion photoelectron spectroscopy. For (naphthalene) n- clusters, two isomers coexist over a wide size range: isomers I and II-1 (28≤n≤60) or isomers I and II-2 (n∼60). Their contributions to the photoelectron spectra can be separated using an anion beam hole-burning technique. In contrast, such an isomer coexistence is not observed for (acenaphthene) n- and (azulene) n- clusters, where isomer I is exclusively formed throughout the whole size range. The vertical detachment energies (VDEs) of isomer I (7≤n≤100) in all the anionic clusters depend linearly on n-13 and their size-dependent energetics are quite similar to one another. On the other hand, the VDEs of isomers II-1 and II-2 produced in (naphthalene) n- clusters with n∼30 remain constant at 0.84 and 0.99 eV, respectively, 0.4-0.6 eV lower than those of isomer I. Based upon the ion source condition dependence and the hole-burning photoelectron spectra experiments for each isomer, the energetics and characteristics of isomers I, II-1, and II-2 are discussed: isomer I is an internalized anion state accompanied by a large change in its cluster geometry after electron attachment, while isomers II-1 and II-2 are crystal-like states with little structural relaxation. The nonappearance of isomers II-1 and II-2 for (acenaphthene) n- and (azulene) n- and a comparison with other aromatic cluster anions indicate that a highly anisotropic and symmetric π -conjugated molecular framework, such as found in the linear oligoacenes, is an essential factor for the formation of the crystal-like ordered forms (isomers II-1 and II-2). On the other hand, lowering the molecular symmetry makes their production unfavorable. © 2008 American Institute of Physics.

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Thermal and hyperthermal collision-energy depositions of transition metal-benzene sandwich complexes onto a self-assembled n-octadecanethiol monolayer

S. Nagaoka, K. Ikemoto, T. Matsumoto, M. Mitsui, A. Nakajima

Journal of Physical Chemistry C （American Chemical Society） 112 （ 17 ） 6891 - 6899 2008年04月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 1932-7447

Gas-phase synthesized transition metal-benzene sandwich complexes of M(benzene)2 (M = Ti, V, and Cr) are soft-landed onto a self-assembled monolayer of n-octadecanethiol (C18-SAM) at a collision energy of 10-20 eV. The resulting adsorption states and thermal desorption kinetics of the soft-landed complexes are studied with infrared reflection absorption spectroscopy and temperature-programmed desorption. The complexes keep their native sandwich structure intact on the SAM substrate even after the "hyperthermal" deposition event. The soft-landed complexes are oriented with their molecular axes largely tilted off the surface normal of the SAM substrate and exhibit unusually large desorption activation energies (E d = ∼130 kJ/mol). For comparison, thermal deposition (∼25 meV) of Cr(benzene)2 vapor onto the C18-SAM, carried out using a physical vapor deposition technique, showed that the complexes are weakly physisorbed (Ed = ∼70 kJ/mol) on the SAM with a random orientation. Only a hyperthermal collision event allows the incident complexes to penetrate into the SAM matrix. The desorption of the embedded complexes in the SAM is then suppressed to around room temperature and may be associated with the crystal-rotator phase transitions of the SAM matrix. © 2008 American Chemical Society.

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Nanosurface-confined anisotropic growth and magnetism of ellipsoidal α-Fe nanogranules

S. H. Huh, C. Kim, D. Riu, Y. Taguchi, A. Nakajima

Journal of Nanoscience and Nanotechnology （American Scientific Publishers） 8 （ 4 ） 1959 - 1964 2008年04月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 1533-4880

We have investigated the nanosurface-confined anisotropic growth of ordered-ellipsoidal Fe nanogranules when an Fe plume was deposited at a slanting angle onto an anodized aluminum oxide (AAO) film. Layer-by-layer growth was also investigated. This growth is driven by two critical factors: (1) a new rhombic AAO cell and (2) the slanting deposition of the Fe plume. During slanting deposition, the rhombic AAO cell induces strong restrictions in the nucleation site, growth direction, and granular size; therefore, the degree of freedom during growth is restricted. The magnetic dipoles of the ordered Fe nanogranules are placed along the long axis of the ellipsoid at an angle of 180° (antiparallel) due to the demagnetizing field, shape anisotropy, and magnetic dipole-to-dipole interactions. Copyright © 2008 American Scientific Publishers All rights reserved.

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Stern-Gerlach study of multidecker lanthanide-cyclooctatetraene sandwich clusters

K. Miyajima, M. B. Knickelbein, A. Nakajima

Journal of Physical Chemistry A （American Chemical Society） 112 （ 3 ） 366 - 375 2008年01月

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

Multilayer lanthanide-cyclooctatetraene organometallic clusters, Ln n(C8H8)m, (Ln = Eu, Tb, Ho, Tm; n = 1 - 7; m = n - 1, n, n + 1) were produced by a laser vaporization synthesis method. The magnetic deflections of these organometallic sandwich clusters were measured by a molecular beam magnetic deflection technique. Most of the sandwich species displayed one-sided deflection, while some of smaller Ln-C 8H8 clusters showed symmetric broadening without or with only very small (or absent) net high-field deflection. In general, the total magnetic moments, calculated from the magnitude of the beams deflections, increase with the number of lanthanide atoms (i.e., with increasing sandwich layers); however for Tb-, Ho-, and Tm-C8H8 clusters with n > 3, the suppression of the magnetic moments was observed, possibly through antiferromagnetic interactions. For Eu-C8H8 clusters, we observe a linear increase of the magnetic moments with the number of Eu atoms up to n = 7, with average magnetic moment per Eu atom around 7 μB - similar to that displayed by conventionally synthesized mononuclear Eu IIC8H8 complexes, indicating that Eu atoms exist as Eu2+ ions in the full sandwich Eun(C 8H8)n+1 clusters. These results suggest that Eun(C8H8)n+1 is a promising candidate for a high-spin, one-dimensional building block in organometallic magnetic materials. © 2008 American Chemical Society.

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Comprehensive photoelectron spectroscopic study of anionic clusters of anthracene and its alkyl derivatives: Electronic structures bridging molecules to bulk

N. Ando, M. Mitsui, A. Nakajima

Journal of Chemical Physics （American Institute of Physics） 127 （ 23 ） 234305 - (13 pages) 2007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 00219606

The evolution of the electronic structure of molecular aggregates is investigated using anion photoelectron (PE) spectroscopy for anionic clusters of anthracene (Ac) and its alkyl derivatives: 1-methylanthracene (1MA), 2-methylanthracene (2MA), 9-methylanthracene (9MA), 9,10-dimethylanthracene (DMA), and 2-tert-butylanthracene (2TBA). For their monomer anions (n=1), electron affinities are confined to the range from 0.47 to 0.59 eV and are well reproduced by density functional theory calculations, showing the isoelectronic character of these molecules. For cluster anions (n=2-100) of Ac and 2MA, two types of isomers I and II coexist over a wide size range: isomers I and II-1 (4≤n<30) or isomers I and II-2 (n∼40 for Ac and n∼55 for 2MA). However, for the other alkyl-substituted Ac cluster anions (i.e., 1MA, 9MA, DMA, and 2TBA), only isomer I is exclusively formed, and neither isomer II-1 nor II-2 is observed. The vertical detachment energies (VDEs) of isomer I in all the anionic clusters depend almost linearly on n-13. In contrast, the VDEs of isomers II-1 (n14) and II-2 (n=40-100), appeared only in Ac and 2MA cluster anions, remain constant with n and are ∼0.5 eV lower than those of isomer I. The PE spectra revealed the characteristics of each isomer: isomer I possesses a monomeric anion core that is gradually embedded into the interior of the cluster with increasing n. On the other hand, isomers II-1 and II-2 possess a multimeric (perhaps tetrameric) anion core, but they differ in the number of layers from which they are made up; monolayer (isomer II-1) and multilayers (isomer II-2) of a two-dimensionally ordered, finite herringbone-type structure, in which electron attachment produces only little geometrical rearrangement. Moreover, the agreement of the constant VDEs of isomer II-2 with the bulk data demonstrates the largely localized nature of the electronic polarization around the excess charge in a crystal-like environment, where about 50 molecules provide a charge stabilization energy comparable to the bulk. © 2007 American Institute of Physics.

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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） 111 （ 42 ） 10884 - 10884 2007年09月

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

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Mass spectrometry and photoelectron spectroscopy of tetracene cluster anions, (tetracene)_n^- (n = 1-100): Evidence for the highly localized nature of polarization in a cluster analogue of oligoacene crystals

M. Mitsui, N. Ando, A. Nakajima

Journal of Physical Chemistry A （American Chemical Society） 111 （ 39 ） 9644 - 9648 2007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 10895639

Photoelectron spectroscopy of tetracene cluster anions, (tetracene) n- (n = 1 -100), reveals the coexistence of two types of isomers, designated as isomers I and II-1 (n = 10-50) or isomers I and II-2 (n > 60), in a wide size range. The vertical detachment energies (VDEs) of isomer I increase persistently due to polarization and structural relaxation effects, where a monomelic anion core is encompassed with geometrically reorganized neutral molecules. Conversely, a characteristic ion distribution in the mass spectrum of (tetracene)n- ensues from the two-dimensional (2D) herringbone-type ordering of isomer II-1, whose VDEs remain constant at 1.80 eV for n ≥ 14. Also, isomer II-2, presumably adopting multilayered structural motifs, exhibits invariable VDEs of 2.0 eV, a manifestation of significant charge screening effects in these isomers. The invariable nature of the VDEs of isomers II-1 and II-2 unambiguously demonstrates a largely localized nature of polarization induced by the excess charge residing in microscopic crystal-like environments. Surprisingly, only 14 tetracene molecules within a 2D herringbone-type layer including an excess charge can provide the charge stabilization energy corresponding to ∼80% of that of the crystal, and the rest of the energy is provided by polarization of neutral molecules in adjacent layers. © 2007 American Chemical Society.

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Generation of high-quality lines and arrays using nanoparticle controlling processes

S. H. Huh, D. Riu, Y. Naono, Y. Taguchi, S. Kawabata, A. Nakajima

Applied Physics Letters （American Chemical Society） 91 （ 9 ） 093118 2007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 0003-6951

Highly reliable lines and arrays comprising the smallest metallic nanoparticles (NPs) were produced by using a combination of techniques such as lithography, lift-off, size selection, aerosol deposition, and NP colloids. The narrowest 80 nm Au lines were produced by the deposition of only 4 nm Au NPs, driven by two factors-NP kinetics and collision-induced surface melting. An array of unsupported free 30-100 Ni NPs and one of 20-40 nm Ni NPs supported in holes were produced by the principles of hole-size-induced filtering and the binding of thiol groups. © 2007 American Institute of Physics.

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Stern-Gerlach experiments of one-dimensional metal-benzene sandwich clusters: M_n(C₆H₆)_m (M = Al, Sc, Ti, and V)

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

Journal of the American Chemical Society （American Chemical Society） 129 （ 27 ） 8473 - 8480 2007年06月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 00027863

A molecular beam of multilayer metal-benzene organometallic clusters M n(C6H6)m (M = Al, Sc, Ti, and V) was produced by a laser vaporization synthesis method, and their magnetic deflections were measured. Multidecker sandwich clusters of transition-metal atoms and benzene Scn(C6H6)n+1 (n = 1, 2) and Vn(C6H6)n+1 (n = 1-4) possess magnetic moments that increase monotonously with n. The magnetic moments of Al(C6H6), Scn(C6H 6)n+1, and Vn(C6H6) n+1 are smaller than that of their spin-only values as a result of intracluster spin relaxation, an effect that depends on the orbital angular momenta and bonding characters of the orbitals containing electron spin. While Ti(C6H6)2 was found to be nonmagnetic, Ti n(C6H6)n+1 (n = 2, 3) possess nonzero magnetic moments. The mechanism of ferromagnetic spin ordering in M 2(C6H6)3 (M = Sc, Ti, V) is discussed qualitatively in terms of molecular orbital analysis. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition-metal atoms are formally zerovalent. © 2007 American Chemical Society.

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Designable formation of metal nanoparticle array with the deposition of negatively charged nanoparticles

S. Kawabata, Y. Naono, Y. Taguchi, S. H. Huh, A, Nakajima

Applied Surface Science （Elsevier Science BV） 253 （ 16 ） 6690 - 6696 2007年06月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 0169-4332

Ultrafine gold and platinum nanoparticles (NPs) were fabricated by pulsed laser ablation in helium gas and the NPs 2-15 nm in diameter were selectively classified by an electrostatic size-selection technique employing a low-pressure differential mobility analyzer (LP-DMA). The spherical NPs obtained showed a narrower distribution of diameters of anionic NPs over cationic NPs. With this knowledge, the anionic NPs were deposited onto silicon substrates designed by electron beam lithography processing, and designable patterns of arrayed NPs were produced by removing the photoresist layer. © 2007 Elsevier B.V. All rights reserved.

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Formation of Large molecular cluster anions and elucidation of their electronic structures

M. Mitsui, A. Nakajima

Bulletin of the Chemical Society of Japan （Chemical Society of Japan） 80 （ 6 ） 1058 - 1074 2007年06月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り, ISSN 0009-2673

The present account describes our efforts to understand the microscopic aspects of condense phase phenomena, such as ion solvation in molecular liquids and charge carrier localization in molecular solids, by viewing finite-size molecular clusters as their embryonic forms. In this effort, we efficiently prepared supersonically cooled, isolated molecular cluster anions with up to more than 100 constituent molecules and size-selectively investigated their electronic structures using anion photoelectron spectroscopy. Large anionic clusters of two different types of organic molecule; acetonitrile and naphthalene reported as examples of the noteworthy results obtained in our studies. In these two systems, we found that energetically close anionic isomers coexist over a broad range in size, and their contribution in the photoelectron spectra could be separated using anion beam hole-burning technique. A detailed inspection into the electronic states and size-dependent energetics of each isomer has enabled us to establish a link from the large finite cluster to the infinite bulk system. © 2007 The Chemical Society of Japan.

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Fabrication and characterization of a granular film consisting of size-selected silver nanoparticles: Application to a SERS substrate

S. Kawabata, N. Ishikawa, M. Mitsui, A. Nakajima

European Physical Journal D （Springer Nature） 43 （ 1-3 ） 155 - 158 2007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 14346060

Uniform-sized silver nanoparticles with average diameter of 13.7 nm have been prepared in the gas-phase by combining a pulsed laser ablation method with a low pressure-differential mobility analyzer (LP-DMA). By depositing the silver nanoparticles onto a silicon substrate, a granular film consisting of size-selected silver nanoparticles has been fabricated and its morphology and electronic properties have been examined using transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. This granular silver film serves as a highly active substrate for surface-enhanced Raman scattering (SERS). © EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007.

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Magnetic trapping of nanometer- and micrometer-sized particles

S. H. Huh, C. Y. Kim, H. S. Jeong, A. Nakajima

Journal of Applied Physics （American Institute of Physics） 101 （ 10 ） 104317 2007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 0021-8979

Nanometer- and micrometer-sized particles (NPs and MPs) of gas-phase Co, Fe, and Fe-Nd-Dy-B were magnetically trapped on a substrate. For the magnetic trapping of NPs, two stepwise evolutions were investigated: (1) the formation of NP aggregates above a critical diameter of 8 nm and (2) increase in the length to a few micrometers, which is the result of the equilibrium between the magnetostatic and thermal energies of NPs and the granular linear chains such as granular nanorods and nanofibers. The magnetic trapping of MPs or MPsNPs is particularly interesting because of the sequential pearl-necklace-like growth and magnetic separation in the linear chains. © 2007 American Institute of Physics.

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