Publications by authors named "Hiroshi Ohoyama"

The alignment of molecular electronic levels in a molecular multilayer is of crucial importance to realize desired functions for molecular devices. Amplitude-modulation-feedback frequency-modulation electrostatic force microscopy combined with Fowler-Nordheim tunneling spectroscopy is utilized as a probe for the energy-level alignment in an organic multilayer. Bias-dependent electrostatic force spectra were examined for bilayers including a Ru complex as a benchmark multilayer system.

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Plasmon-induced charge separation (PICS) is an efficient way to use the hot carriers generated by localized surface plasmon resonance. Although the ultrafast dynamics of hot carrier generation and annihilation itself are well understood, the slow dynamics of PICS are not, despite their importance for the use of hot carriers in chemical reactions. In this work, we directly observed the slow dynamics of PICS on an Au nanoparticle (NP)/TiO interface by using electrostatic force microscopy with time-resolved measurements obtained by sideband signal of frequency shift.

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A sulfonated polyaniline (SPAN) organic electrochemical network device (OEND) is fabricated using a simple drop-casting method on multiple Au electrodes for use in reservoir computing (RC). The SPAN network has humidity-dependent electrical properties. Under high humidity, the SPAN OEND exhibits mainly ionic conduction, including charging of an electric double layer and ionic diffusion.

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Ionic liquids (ILs) are known for their high ability to capture CO. However, the mechanism of CO solubility into ILs during their initial interaction remains controversial. In this study, we analyzed the initial dissolution of CO into an IL 1-butyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide ([Cmin] [NTf]) by measuring its solubility using a combination of a molecular beam and a flowing liquid jet sheet beam (FJSB) and the King and Wells method (KW method).

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Charge dynamics play an important role in numerous natural phenomena and artificial devices, and tracking charge migration and recombination is crucial for understanding the mechanism and function of systems involving charge transfer. Tip-synchronized pump-probe electrostatic force microscopy simultaneously permits highly sensitive detection, microsecond time resolution, and nanoscale spatial resolution, where the spatial distribution in static measurement (usual EFM) reflects differences in the carrier density and the time evolution reveals the surface carrier mobility. By using this method, carrier injection and ejection in sulfonated polyaniline (SPAN) thin films were visualized.

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Current-voltage (-) nonlinearity is essential for information processing in molecular electronics. We used a nanoparticle bridge junction to investigate the effect of electronic coupling between a Ru complex and electrodes on nonlinear electrical properties. Two types of molecular layers, in which the Ru complex forms different chemical bondings to the electrode, were used for electrical measurements.

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Nonlinear current-voltage (I-V) characteristics is an important property for the realization of information processing in molecular electronics. We studied the electrical conduction through a Ru-dye complex (N-719) on a 2-aminoethanethiol (2-AET) monolayer in a nanoparticle bridge junction system. The nonlinear I-V characteristics exhibited a threshold voltage at around 1.

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Atomic orbital alignment effect was observed for the CN (B2Sigma+) formation in the reaction of oriented Ar (3P2) with CH3CN (CD3CN). The relative cross-sections for each magnetic MJ' substrate in collision frame sigmaH|MJ'| for CH3CN and sigmaD|MJ'| for CD3CN, were determined to be sigmaH0:sigmaH|1|:sigmaH|2|:sigmaD0:sigmaD|1|:sigmaD|2| = 1.00:0.

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