記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The effects of supramolecular encapsulation on the photophysics and photostability of a highly fluorescent dimeric derivative of 2,6-diacetox-y-9,10-bis(arylethynyl)anthracene (G2) were investigated by single-molecule fluorescence spectroscopy (SMFS). The fluorescence properties of free-G2 and its self-assembled boronic ester encapsulation complex, G2@(Cap)(2), were compared in solution and a glassy polymer film. The fluorescence spectral characteristics and theoretical calculations suggest that the environment affects the excited-state conformation and subsequent fluorescence emission of G2@(Cap)(2). In particular, in the liquid and polymer environments, G2@(Cap)(2) emits a fluorescence photon in the planar and twist conformation, respectively, whereas the fluorescence-emitting conformation of free-G2 is planar in both environments. The luminous conformation differences between free-G2 and G2@(Cap)(2) in polymer are reflected in the intersystem crossing (ISC) parameters (the ISC quantum yield and triplet lifetime), as determined by fluorescence autocorrelation analysis. The photobleaching yield revealed a 3-fold enhancement in the photostability of encapsulated G2 (relative to free-G2). Under the SMFS measurement conditions, the photostability of the encapsulation complex was independent of the guest's photostability and appeared to be dominated by the thermal stability of the Cap host molecule.

DOI： 10.1021/acs.jpca.6b08734

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Fluorescence on-off blinking of single perylenediimide (DMP-PDI) dyes embedded in a disordered matrix of poly(methyl methacrylate) (PMMA) was investigated by single-molecule fluorescence spectroscopy. In particular, we examined the bin-time dependencies of the complementary cumulative distribution functions (cCDF) of the on-time and off-time durations. It appears that intersystem crossing (ISC) within DMP-PDI competes with charge transfer between DMP-PDI and PMMA. The single-molecule and ensemble cCDFs of the on-time and off time durations (induced by charge transfer) were best described by Weibull functions and log-normal functions, respectively. The dispersive kinetics of the on-time duration were attributed to radical ion pair ISC from triplet charge separation ((CS)-C-3) state to the corresponding singlet ((CS)-C-1) state via charge hopping between charge trap sites in PMMA. This process should compete with triplet charge recombination ((CR)-C-3) which restores the triplet state. On-to-off switching occurs only when (CS)-C-3 -> (CS)-C-1 ISC overcomes the (CR)-C-3 process. The resultant Weibull distribution (with A < 1) reflects that the probability of charge hopping rapidly decreases with time. On the other hand, the off time log-normal kinetics of single-molecules are explained by a Gaussian distribution of activation energies for charge recombination (the so-called Albery model). A simulation study revealed that the ensemble off-time cCDF included power-law kinetics of charge hopping in the polymer matrix.

DOI： 10.1021/acs.jpcc.6b04114

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Newly developed simultaneous scanning photocurrent and luminescence microscopy was applied to ruthenium-based dye-sensitized solar cells (DSCs) comprising a cover glass photoanode with a 100 nm thick TiO2 layer. Using this, we have investigated the lateral variations of several parameters of these DSCs under short-circuit conditions. Simultaneous measurement of photocurrent and luminescence images for the same area of the DSC demonstrated submicrometric lateral resolution of our photo current microscopy, which is approximately 10 times better than the resolution of photo current microscopy used in past studies. The photovoltaic parameters, such as short-circuit current density, open-circuit voltage, and charge-collection efficiency, were thus evaluated for local (or submicrometric) regions of the DSCs. Furthermore, the photocurrent saturation behavior of the DSCs was examined as a function of the excitation rate and analyzed on the basis of a three-state kinetic model. This protocol allowed for quantification of the dye-adsorption number and dye-regeneration rate constant for any local area of the DSCs. Consequently, the correlations between the dye adsorption number, photovoltaic parameters, and regeneration rate constant, which are difficult to address through examination of the entire cell, were revealed by the "zoom-in" approach utilizing this high-resolution photocurrent microscopy.

DOI： 10.1021/acs.langmuir.5b01581

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-V C H VERLAG GMBH  

The self-assembled boronic ester cavitand capsule 3 quantitatively and tightly encapsulates 2,6-diacetoxy-9,10-bis(arylethynyl)anthracene derivatives 4a-4c as highly fluorescent cruciform guests to form complexes 4a@3, 4b@3, and 4c@(3)(2). The structural features of capsule 3, which possesses two polar bowl-shaped aromatic cavity ends and four large equatorial windows connected by dynamic boronic ester bonds, made it possible to encapsulate cruciform 4 with protection of the reactive anthracene core inside the capsule and with two protruding arylethynyl groups, the -conjugated arms of compound 4, through two of the equatorial windows of the capsule. Thus, complexes 4a@3, 4b@3, and 4c@(3)(2) show greater resistance to photochemical reactions in solution and fluorescence quenching in the powder state compared to free guests 4. In addition to the improved photostability, restriction of the free rotation of the arylethynyl groups of guests 4 upon encapsulation results in sharpening of the UV/Vis absorption peaks with a red-shift and a significant increase in some of the two-photon-absorption peaks of complexes 4a@3, 4b@3, and 4c@(3)(2) compared with free guests 4.

DOI： 10.1002/asia.201400042

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

For single-molecule fluorescence studies, highly photostable fluorophores are absolutely imperative, because photo-induced degradation (i.e., photobleaching) limits the observation time of individual molecules. Herein, the photophysics and photostability of a highly fluorescent 9,10-bis(phenylethynyl) anthracene derivative (G) and its self-assembled boronic ester encapsulation complex (G@Cap) embedded in a glassy polymer matrix are investigated by single-molecule fluorescence spectroscopy (SMFS). The heterogeneity of the fluorescence emission wavelength and triplet blinking kinetics of the guest G are significantly decreased by supramolecular encapsulation due to conformational restriction and reduced heterogeneity in the local environment. A nearly 10-fold increase in the photostability of G due to encapsulation is quantitatively confirmed by evaluating the photobleaching yields of G and G@Cap. In addition, it is found that the G@Cap is > 30-fold more photostable than rhodamine 6G, a widely used fluorescent dye in single-molecule studies. These results demonstrate that the G@Cap can serve as a very bright, long-lasting fluorescent probe for single-molecule studies.

DOI： 10.1039/c4pp00065j

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

A series of tetracene (Tc)-doped p-terphenyl (pTP) nanoparticles (Tc/pTP-NPs) were produced at various doping ratios by reprecipitation in water. The Tc/pTP-NPs are disk-like with a mean diameter of 75 nm and height of 7 nm, which were determined by scanning electron microscopy and atomic force microscopy, and exhibited electronic delocalization through H-type aggregation of the pTP molecules. Electronic energy transfer in the Tc/pTP-NPs was examined using steady-state and time-resolved fluorescence spectroscopy and fluorescence anisotropy experiments: pTP-NPs serve as an excellent light-harvesting nano-matrix with a large absorption coefficient that exceeds 10(9) M (1) cm (1). Furthermore, Stern-Volmer analysis of the donor emission was performed by changing the dopant concentration; this showed that a single Tc acceptor quenched more than 10(4) pTP donors. Comparison of the experimental and theoretical energy transfer efficiencies indicated that the efficient energy transfer can be attributed to two-dimensional exciton diffusion in the host nanoparticles. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chemphys.2013.01.004

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

The photophysics and photostability of 9,10-bis(phenylethynyl) anthracene (BPEA) diluted in a 40-nm-thick Zeonex polymer film have been investigated by single-molecule spectroscopy (SMS). The single-molecule detection of BPEA was verified by recording fluorescence intensity trajectories, fluorescence lifetimes, and fluorescence spectra. The intensity trajectories showed frequent on/off blinking and one-step photobleaching behaviors. The observed blinking was attributed to the temporary occupation of the excited triplet state T-1 via intersystem crossing (ISC). Assuming a three-state model (e.g., S-0, S-1, and T-1), the distributions of triplet lifetime and S-1 -> T-1 ISC quantum yield of BPEA were both derived from the analyses of the blinking statistics and the intensity autocorrelation. We found extremely low ISC yields (on the order of 10(-5)-10(-4)), which were theoretically rationalized by the large energy gap between B-3(2u) and S-1(B-1(1u))/T-1(B-3(1u)) states. SMS measurements were also conducted under both air and Ar atmospheres in order to gain insight into the influence of oxygen on photobleaching. The results reveal that, although the presence of oxygen considerably degraded the photostability of BPEA, under deoxygenated conditions, BPEA delivers more than 10(7) photons before photobleaching and possesses an appreciably low photobleaching yield of 10(-9)-10(-8). This study shows that BPEA has a relatively high degree of photostability at room temperature and can serve as a useful green fluorescent probe for SMS studies.

DOI： 10.1039/c2ra21100a

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：日本分光学会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Gas-phase synthesized Cr(benzene)(2) sandwich complexes were soft-landed onto a carboxyl-terminated self-assembled monolayer (C15COOH-SAM) on a gold substrate at hyperthermal collision energy (5-20 eV). The deposition process and adsorption properties of the soft-landed complexes were investigated by means of infrared reflection absorption spectroscopy (IRAS) and temperature programmed desorption (TPD) measurements. With the soft-landing, the Cr(benzene)(2) complexes are adsorbed at the SAM surface while keeping their native sandwich structure intact even after the hyperthermal collision event. Moreover, the complexes tend to orient their molecular axes reasonably or comparatively close to the surface normal direction to the SAM surface. This orientation might arise from chemical interactions between the benzene ring in the sandwich complexes and carboxyl groups on the SAM surface. An Arrhenius analysis of the TPD spectra reveals the desorption activation energy of soft-landed complexes as 133 +/- 10 kJ/mol, a value which is comparable to typical adsorption heat of chemisorptions. Chemical interactions between the Cr(benzene)(2) complexes and carboxyl groups would provide firm trapping of the complexes at the SAM surface, preventing the supported complexes from being desorbed until near room temperature.

DOI： 10.1021/jp807137p

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Metal-rich K1-5(KI)(n)(+) (n similar to 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 K-1(KI)(n); n = 8, 12, and 21 for K-2(KI)(n); n = 8, 12, 16, and 21 for K-3(KI)(n); n 7, 9, 11, and 13 for K-4(KI)(n); and n = 12 and 21 for K-5(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 K-2.3,K-5(KI)(n)(+) clusters have the same magic numbers at n = 12 and 21 and possess structures that are closely related to the 3 x 3 x 3 and 3 x 3 x 5 cubic structures with the excess electron at the side anion vacancy or the center anion vacancy. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molstruc.2007.02.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions, (o-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 monomeric 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 monomeric 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.

DOI： 10.1021/jp801159n

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

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 (C-18-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 = similar to 130 kJ/mol). For comparison, thermal deposition (similar to 25 meV) of Cr(benzene)2 vapor onto the C-18-SAM, carried out using a physical vapor deposition technique, showed that the complexes are weakly physisorbed (E-d = similar to 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.

DOI： 10.1021/jp711695s

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Photoelectron spectroscopy of tetracene cluster anions, (tetracene), (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 monomeric anion core is encompassed with geometrically reorganized neutral molecules. Conversely, a characteristic ion distribution in the mass spectrum of (tetracene),, 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 similar to 80% of that of the crystal, and the rest of the energy is provided by polarization of neutral molecules in adjacent layers.

DOI： 10.1021/jp076134h

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

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.

DOI： 10.1246/bcsj.80.1058

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Electronic properties of silicon and germanium atom doped indium clusters, InnSim and InnGem, were investigated by photoionization spectroscopy of the neutrals and photoelectron spectroscopy of the anions. Size dependence of ionization energy and electron affinity for InnSi1 and InnGe1 exhibit pronounced even-odd alternation at cluster sizes of n = 10-16, as compared to those for pure In-n clusters. This result shows that symmetry lowering with the doped atom of Si or Ge results in undegeneration of electronic states in the 1d shell formed by monovalent In atoms.

DOI： 10.1021/jp065921w

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Silicon clusters mixed with a transition metal atom, MSin, were generated by a double-laser vaporization method, and the electronic and geometric stabilities for the resulting clusters with transition metal encapsulated by silicon were examined experimentally. By means of a systematic doping with transition metal atoms of groups 3, 4, and 5 (M = Sc, Y, Lu, Ti, Zr, Hf, V, Nb, and Ta), followed by changes of charge states, we explored the use of an electronic closing of a silicon caged cluster and variations in its cavity size to facilitate metal-atom encapsulation. Results obtained by mass spectrometry, anion photoelectron spectroscopy, and adsorption reactivity toward H2O show that the neutral cluster doped with a group 4 atom features an electronic and a geometric closing at n = 16. The MSi16 cluster with a group 4 atom undergoes an electronic change in (i) the number of valence electrons when the metal atom is substituted by the neighboring metals with a group 3 or 5 atom and in (ii) atomic radii with the substitution of the same group elements of Zr and Hf. The reactivity of a halogen atom with the MSi16 clusters reveals that VSi16F forms a superatom complex with ionic bonding.

DOI： 10.1021/jp066757f

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Silicon clusters mixed with a transition metal atom, MSin, were generated by a double-laser vaporization method, and the electronic and geometric stabilities for the resulting clusters with transition metal encapsulated by silicon were examined experimentally. By means of a systematic doping with transition metal atoms of groups 3, 4, and 5 (M = Sc, Y, Lu, Ti, Zr, Hf, V, Nb, and Ta), followed by changes of charge states, we explored the use of an electronic closing of a silicon caged cluster and variations in its cavity size to facilitate metal-atom encapsulation. Results obtained by mass spectrometry, anion photoelectron spectroscopy, and adsorption reactivity toward H2O show that the neutral cluster doped with a group 4 atom features an electronic and a geometric closing at n = 16. The MSi16 cluster with a group 4 atom undergoes an electronic change in (i) the number of valence electrons when the metal atom is substituted by the neighboring metals with a group 3 or 5 atom and in (ii) atomic radii with the substitution of the same group elements of Zr and Hf. The reactivity of a halogen atom with the MSi16 clusters reveals that VSi16F forms a superatom complex with ionic bonding.

DOI： 10.1021/jp066757f

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The geometric and electronic structures of aluminum binary clusters, AlnX (X) Si and P), have been investigated, using mass spectrometry, anion photoelectron spectroscopy, photoionization spectroscopy, and theoretical calculations. Both experimental and theoretical results show that Al12Si has a high ionization energy and low electron affinity and Al12P has a low ionization energy, both with the icosahedral structure having a central Si or P atom, revealing that Al12Si and Al12P exhibit rare- gas- like and alkali superatoms, respectively. Experiments confirmed the possibility that the change in the total number of valence electrons on substitution could produce ionically bound binary superatom complexes, the binary cluster salts Al12P+F- and Al12B-Cs+.

DOI： 10.1021/jp065161p

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The adsorption state and thermal stability of V( benzene)(2) sandwich clusters soft-landed onto a self- assembled monolayer of different chain-length n-alkanethiols (C-n-SAM, n) 8, 12, 16, 18, and 22) were studied by means of infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). The IRAS measurement confirmed that V(benzene)(2) clusters are molecularly adsorbed and maintain a sandwich structure on all of the SAM substrates. In addition, the clusters supported on the SAM substrates are oriented with their molecular axes tilted 70-80 off the surface normal. An Arrhenius analysis of the TPD spectra reveals that the activation energy for the desorption of the supported clusters increases linearly with the chain length of the SAMs. For the longest chain C-22-SAM, the activation energy reaches similar to 150kJ/mol, and the thermal desorption of the supported clusters can be considerably suppressed near room temperature. The clear chain-length-dependent thermal stability of the supported clusters observed here can be explained well in terms of the cluster penetration into the SAM matrixes.

DOI： 10.1021/jp061806+

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

Adiabatic electron affinities (EA(a)'S) of seven oligophenyls: biphenyl (BP), 4-cyanobiphenyl (CNBP), o-terphenyl (o-TP), m-terphenyl (m-TP), p-terphenyl (p-TP), p-quaterphenyl (p-QP), and 1,3,5-triphenylbenzene (TPB), have been evaluated by anion photoelectron spectroscopy and density functional theory calculations. The result provides the direct determination of the EA(a) values of the isolated CNBP, p-TP, p-QP, and TPB molecules, while EA(a) of BP, o-TP, and m-TP were estimated from the extrapolation of EA(a) vs cluster size. The excellent agreement between the experimental and calculated EA(a) were obtained.

DOI： 10.1246/cl.2006.888

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The effect of Cs atom doping on metallic aluminum clusters and covalent silicon clusters, AlnCsm (n = 5-14, m = 0-3) and SinCsm (n = 5-16, m = 0-3), was examined by mass spectrometry and anion photoelectron spectroscopy. For clusters containing Cs atom(s), the electron affinities of both clusters are generally decreased and the following characteristic features are observed: for AlnCsm Cs-atom doping causes (1) electron filling into the electronic shell structure of the Al-n, clusters and (2) geometrical packing of icosahedral 13-atoms, while for SinCsm Cs-atom doping enhances electronic stability to be ascribed to pure Si-n clusters, particularly at (n, m) = (10, 3) and (13, 1). (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2006.01.118

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

Evolution of electronic structures of nanoscale biphenyl cluster anions, (BP)(n)(-) (n = 2-100), have been studied by photoelectron spectroscopy in a size-selective fashion. The energetics of vertical detachment energy (VDE) revealed negative electron affinity of a biphenyl molecule and substantial cluster reorganizations via electron attachment. Comparison of the VDE energetics with naphthalene cluster anions implied that the freezing (and/or melting) temperatures of the BP clusters may be much lower than those of naphthalene clusters.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

DOI： 10.1021/ja045380t

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

A molecular beam of europium-cyclooctatetraene sandwich nanowires Eu-n(COT)(m) was produced by a laser vaporization synthesis method. The formation mechanism of the nanowires was quantitatively revealed by photoelectron and photoionization spectroscopies of the Eu-COT species, together with supporting theoretical calculations. From these results. it is confirmed that growth processes extending the length of Eu-COT nanowires involve a series of elementary reactions in which efficient charge transfer occur at the terminal reaction sites. In every elementary step, the reaction proceeds between one reactant having low ionization energy and the other reactant having high electron affinity, probably via a "harpoon" mechanism.

DOI： 10.1021/jp0452103

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

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 (pi,pi*) 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,pi(*)) configuration have little intensity, implying a relatively large intramolecular structural relaxation in the (n,pi(*)) states. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1818132

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

Two types of anion states are shown to coexist in nanometer-scale polyacene cluster anions. Naphthalene and anthracene nanoclusters having a single excess electron were produced in the gas-phase. Photoelectron spectra of size-selected cluster anions containing 2 to 100 molecules revealed that rigid "crystal-like" cluster anions emerge, greater than similar to2 nanometers in size, and coexist with the "disordered" cluster anion in which the surrounding neutral molecules are reorganizing around the charge core. These two anion states appear to be correlated to negative polaronic states formed in the corresponding crystals. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1809118

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

We have studied the electronic structures of several gas phase exohedral lanthanide (Ln)-C-60 clusters, Ln(n)C(60) (Ln=Pr, Ho, Tb, Tm, Eu, and Yb) with n=1-4, by photoionization spectroscopy of the neutrals and photoelectron spectroscopy of their anions. Both of the spectroscopic analyses reveal that most of the Ln atoms preferably take +3 oxidation states, while Eu atoms alone assume +2 oxidation states, and that C-60 accepts up to twelve donated electrons in Ln(n)C(60). An additional photoionization examination of the oxygen atom mixing into the Ln(n)C(60) clusters demonstrated that each oxygen atom reduces two electrons from C-60. This result implies that the number of accepted electrons in C-60 can be varied by a suitable choice of the number of Ln atoms and O atoms. (C) 2004 American Institute of Physics.

DOI： 10.1063/1.1767514

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Pyrene molecular anion and its homogeneous clusters, (pyrene)(n)(-) (n = 2-20), have been studied by anion photoelectron spectroscopy. The adiabatic electron affinity (EA(a)) of pyrene was directly determined to be 0.406 +/- 0.010 eV. This EA(a) 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. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2004.03.100

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/jp035235m

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

We present a negative ion photoelectron spectroscopic study on the solvation energetics of an excess electron in the size-selected aromatic hydrocarbon nanoclusters, (benzene)(n)(-) (n=53-124) and (toluene)(n)(-) (n=33-139). The formation and stability of these negatively charged clusters were investigated using mass spectrometry with two different sources: (1) low-energy (approximate to0.3 eV) electron attachment and (2) high-energy electron impact. The results reveal that very large coordination numbers (nsimilar to25) are necessary for the formation of stable benzene and toluene cluster anions. This suggests that the second solvation layer (effect) is essential for stable binding of the excess electron in these clusters. The energetics of the cluster anions were also explored by negative ion photoelectron spectroscopy. The photoelectron spectra obtained were related to bulk parameters, e.g., solvent reorganization energy and conduction band minimum, via an analysis of vertical detachment energies versus n(-1/3). The bulk solvent reorganization energies thus estimated have revealed the excess electron trapping levels in bulk benzene and toluene. The applicability of the generalized cluster size equation is examined in these nondipolar aromatic hydrocarbon systems for the first time. (C) 2002 American Institute of Physics.

DOI： 10.1063/1.1516793

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

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 Au-n clusters are compared to those of pure Au-n clusters. A peak shape analysis reveals electronic and geometric similarity between Au-n(-) and Aun-1 Pd- 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 sigma orbital between 6s of Au and 5s of Pd. (C) 2002 Published by Elsevier Science B.V.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

Negatively charged benzene clusters, (benzene)(n)(-), were produced by injecting low- and high-energy electrons into an intense supersonic jet expansion. Threshold size of n=53 was observed by slow-electron attachment, while the smaller (benzene)(n)(-) with 2 less than or equal ton less than or equal to 52 were also observed through the fragmentation of larger (benzene)(n)(-) by high-energy electron attachment. Photoelectron spectroscopy for (benzene)(n)(-) with n=53-124 has revealed a bulklike electron solvated state in (benzene)(n greater than or equal to 53)(-) through the vertical detachment energies (VDEs) versus n(-1/3) relationship. (C) 2001 American Institute of Physics.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

Time-resolved ESR (TR-ESR) spectra were measured in the laser excitation of aromatic compounds such as xanthone, bromopyrene, fluoranthene (Flt) and pyrene (Py) in sodium dodecyl sulfate (SDS) aqueous micellar system in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). Net emission (Em) signals of triplet hyperfine (hf) lines of TEMPO were observed in xanthone- and bromopyrene-TEMPO systems. The chemically induced dynamic electron polarization (CIDEP) was explained by radical-triplet pair mechanism. Antiphase signals of TEMPO with Ern in low-field side and enhanced absorption in high-field side (EA) of each triplet hf line were superimposed on net Ern signals in Flt- and Py-TEMPO systems. The square laser power dependence of the EA signal suggests that the two-photon ionization of Flt and Py is related to the EA antiphase signal. Rate constants of the reactions occurring in SDS solution were determined by analysis of transient absorption decays in the Py-TEMPO system. The reaction rates of Py+-TEMPO and Py-3*-TEMPO in SDS solution were determined as 1.2 X 10(6) s(-1) and 3.0 X 10(5) s(-1), respectively, at the TEMPO concentration of 2 mM (M = mol dm(-3)). According to these measurements, it was concluded that the EA CIDEP is due to spin-correlated radical pair (SCRP) of TEMPO and Py+ which was formed in the electron transfer reaction from TEMPO to Py+. Simulation of TR-ESR spectra was carried out using SCRP theory. From kinetic analysis of intermediates together with the simulation of TR-ESR spectra, it was concluded that both SCRP of Py+-TEMPO and RTPM of Py-3*-TEMPO contribute to the CIDEP of TEMPO.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The present paper represents fluorescence-detected infrared measurements of 9(10H)-acridone (AD) and 10 of its fluorescent hydrated clusters, AD-(H2O), (n = 1-5 and more), which have been performed by monitoring the fluorescence from their (1)(pi,pi*) electronic origin transitions reported in paper I. In the n = 1 and 2 clusters, free N-H stretching band has been identified in addition to O-H stretching bands characteristic to water molecules acting as single proton donors. As the next solvation step, the II-bonded O-H stretches are further developed in the red-shifted region and the N-H stretch becomes involved in the hydrogen-bonds for the n = 3-5 clusters. For n greater than or equal to 6, more than one pair of double-donor O-H stretches appear. These spectral features are well correlated to the stepwise evolution in the hydrogen-bonding networks in AD-(H2O)(n), which have been predicted by the (pi,pi*) spectral-shift analysis and DFT calculations presented in paper I: water units are bound to the C=O site for n = I and 2, a single water chain bridges between the C=O and N-H sites above the AD aromatic rings for n = 3-5, and water bridges become branched for n greater than or equal to 6 and probably form three-dimensional cages at higher aggregation levels. Differences in hydrogen-bonding topologies, stabilities, and dynamical behaviors among the conformers are discussed on the basis of the experimental observations, the DFT calculations, and comparison with other hydrated aromatic clusters.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

A series of papers (I-III) reports spectroscopic investigation on structure and dynamics of 9(10H)-acridone (AD) and its hydrated clusters. As the first part of the series, the present paper describes their lowest (1)(pi,pi*) electronic transition in the 370-400 nm region studied by fluorescence-based laser spectroscopy and mass-selective two-color resonance-enhanced two-photon ionization (2C-R2PI). Thirteen fluorescent hydrates as well as the monomer have been identified in fluorescence-excitation and UV-UV hole-burning measurements, and size assignments for relatively smaller clusters, AD-(H2O), (n = 1-6), have been conducted by 2C-R2PI. The origin bands for larger-size clusters show larger red shifts converging at ca. 2200 cm(-1) but the changes are nonmonotonic, with a substantial increase from n = 2 to 3. Density-functional-theory (DFT) calculations at the B3LYP/6-31G(d,p) level have predicted that the energy difference between the C=O and N-H bonded isomers is quite small (only approximate to 1 kcal/mol) for n = 1 and 2. The observed spectral shifts of fluorescent hydrates with n = 1 and 2 are well reproduced by the HOMO-LUMO gap in the DFT orbital energies of either of the N-H or C=O bonded isomers, leaving the definitive structural assignments to fluorescence-detected infrared spectroscopy which will be described in paper II. For the larger clusters (n 3-5), several minimum-energy structures have been identified within 2 kcal/mol in binding energy, among which the conformers with water molecules bridging between the C=O and N-H sites over the AD's aromatic rings are identified as the observed species, based on good agreement between the calculated and observed spectral shifts.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Chemically induced dynamic electron polarization (CIDEP) generated through the interaction between the lowest excited singlet oxygen molecule and 2,2,6,6,-tetramethylpiperidinyl-1-oxyl (TEMPO) radical was observed by the time-resolved ESR technique. Excited singlet oxygen molecules were produced by the triplet sensitizer through energy transfer. Absorptive electron spin polarization was generated on the free radical in the excited singlet oxygen molecule - free radical system, in which the CIDEP generation was interpreted by the radical-triplet pair mechanism with doublet precursor (DP-RTPM). The CIDEP time profile was successfully analyzed by using the Bloch equations. Quenching of O-1(2) by beta-carotene provides further evidence for DP-RTPM in the O-1(2)-TEMPO system.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Chemically induced dynamic electron polarization (CIDEP) generated through the interaction of the excited tripler state of benzophenone with the 2,2,6,6,-tetramethyl-1-piperidinyloxyl (TEMPO) radical was investigated by time-resolved ESR spectroscopy in benzene solution. We carefully examined what factors control the CIDEP intensities. By comparing the CIDEP intensity of TEMPO obtained in the triplet benzophenone-TEMPO system with the intensity in the C-60-TEMPO system, the absolute magnitude of net emissive polarization was determined to be -6.9 in the unit of Boltzmann polarization. The emissive polarization is attributed to state mixing between a quarter and a doublet in the radical-tripler pair induced by the zero-field splitting interaction of the counter triplet molecule. Our result is quantitatively explained by the theory that the net CIDEP is generated predominantly in regions where the quarter and doubler levels cross. This indicates that the quenching of the excited triplet benzophenone by TEMPO in benzene can proceed via an electron-exchange interaction.

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

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記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）   出版者・発行元：SPRINGER VERLAG  

Net absorptive CIDEP generation has been demonstrated on singlet molecular oxygen and 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxyl (OTEMPO) radical system in benzene. CIDEP generation was reasonably explained in terms of the radical-triplet pair mechanism of triplet molecular oxygen-OTEMPO pair with doublet precursor. Several excited molecule-OTEMPO systems have been investigated if this CIDEP generation contributes to their CIDEP spectra. Surprisingly strong CIDEP was produced even in the presence of trace amount of dissolved oxygen, which suggests the importance of complete degassing for CIDEP studies in general systems.

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