慶應義塾大学 · 材料科学
Atsushi Nakajima教授の研究室では、原子・分子レベルの微小なクラスターからなるナノクラスターの構造と電子的性質を、レーザー蒸発法と高感度分光法を組み合わせて解明しています。特に遷移金属を含む有機金属クラスター、半金属・希土類元素を含む金属-半金属クラスター、および水素結合を形成する分子集合体の精密構造と電子状態のサイズ依存性を追求しています。この研究により、ナノスケールでの物性制御と機能性材料の設計が可能になると期待されています。
Figures are computed from collected data and may differ slightly.
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
The electronic properties of germanium and tin clusters containing a transition- or lanthanide-metal atom from group 3, 4, or 5, MGe(n) (M = Sc, Ti, V, Y, Zr, Nb, Lu, Hf, and Ta) and MSn(n) (M = Sc, Ti, Y. Zr, and Hf), were investigated by anion photoelectron spectroscopy at 213 nm. In the case of the group 3 elements Sc, Y, and Lu, the threshold energy of electron detachment of MGe(n)(-) exhibits local maxima at n = 10 and 16, while in the case of the group 4 elements Ti, Zr, and Hf, it exhibit
Aluminum–sodium bimetallic clusters (AlnNam, n=2–26) were produced by two independent laser vaporization methods. To investigate the electronic structures, ionization potentials of the AlnNam clusters were measured up to m=3 using a tunable ultraviolet laser combined with time-of-flight (TOF) mass spectrometer. In general, the ionization potentials monotonically decrease with the number of sodium atoms, and the ionization potentials of Aln Na1 generally decrease by 0.2–0.6 eV compared to those o
The geometric structures of 7-azaindole−water complexes, (7-AzI)-(H2O)n (n = 1−3), and 7-AzI dimer were investigated by laser-induced fluorescence (LIF) spectroscopy with high resolution (∼0.01 cm-1). For the 7-AzI−(H2O)n complexes (n = 1−3), the LIF spectra show partially resolved rotational structure, which has been analyzed in combination with theoretical calculations. This analysis yields the rotational constants and characterizes the structures. In 7-AzI−(H2O)1, the H2O molecule is located
Photoelectron spectra of SinC−m cluster anions (1≤n≤7 and 1≤m≤5) were measured at the photon energies of 3.49 eV, by using a magnetic bottle electron spectrometer. The SinC−m clusters were produced either by a laser vaporization of a silicon–carbon mixed rod or by two laser vaporizations of carbon and silicon rods in a He carrier gas. The spectra of the SinC−1 (3≤n≤7) clusters are similar to those of pure Si−n+1 clusters in the peak positions and their envelopes, which is attributed to the isova
Nanoclusters, aggregates of several to hundreds of atoms, have been one of the central issues of nanomaterials sciences owing to their unique structures and properties, which could be found neither in nanoparticles with several nanometer diameters nor in organometallic complexes. Along with the chemical nature of each element, properties of nanoclusters change dramatically with size parameters, making nanoclusters strong potential candidates for future tailor-made materials; these nanoclusters a
The controlled assembly of superatomic nanocluster ions synthesized in the gas phase is a key technology for constructing a novel series of functional nanomaterials. However, it is generally difficult to immobilize them onto a conductive surface while maintaining their original properties owing to undesirable modifications of their geometry and charge state. In this study, it has been shown that this difficulty can be overcome by controlling the donor-acceptor interaction between nanoclusters an
Vanadium (V)–C60 mixed clusters were produced by two laser vaporization methods. In the mass spectra of cationic Vn(C60)m+, the abundant clusters were produced at the composition of (n,m)=(1,1), (1,2), (2,3), (3–4,4), and (5,5). This pattern is explicable in terms of a multiple dumbbell structure; V atom and C60 are alternatively piled up. The ionization energy and the reactivity of the dumbbell clusters toward O2 and CO show V1(C60)2 takes a structure of V1(η6−C60)2.
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